3:21 a.m.
Hello,
I've been running a multi master configuration without any problem for
years. This running servers are running in 5 ubuntu 14.04 servers with
openldap 2.4.43.
The configuration is:
dn: olcDatabase={3}mdb,cn=config
...
olcSyncrepl: {0}rid=31 provider=ldap://canis31.um.es binddn=<repl user
dn> bindmethod=simple credentials=XXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="300 +" timeout=1
olcSyncrepl: {1}rid=32 provider=ldap://canis32.um.es binddn=<repl user
dn> bindmethod=simple credentials=XXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="300 +" timeout=1
olcSyncrepl: {2}rid=33 provider=ldap://canis33.um.es binddn=<repl user
dn> bindmethod=simple credentials=XXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="300 +" timeout=1
olcSyncrepl: {3}rid=34 provider=ldap://canis34.um.es binddn=<repl user
dn> bindmethod=simple credentials=XXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="300 +" timeout=1
dn: olcOverlay={0}dynlist,olcDatabase={3}mdb,cn=config
objectClass: olcDynamicList
objectClass: olcOverlayConfig
objectClass: olcConfig
olcOverlay: {0}dynlist
olcDlAttrSet: {0}labeledURIObject labeledURI
dn: olcOverlay={1}ppolicy,olcDatabase={3}mdb,cn=config
objectClass: olcPPolicyConfig
objectClass: olcOverlayConfig
objectClass: olcConfig
olcOverlay: {1}ppolicy
olcPPolicyDefault: cn=default,ou=policies,dc=Telematica
dn: olcOverlay={2}syncprov,olcDatabase={3}mdb,cn=config
objectClass: olcSyncProvConfig
objectClass: olcOverlayConfig
objectClass: olcConfig
olcOverlay: {2}syncprov
olcSpCheckpoint: 100 10
olcSpSessionlog: 100
where each server has 4 olcSyncrepl attributes pointing to the other
servers.
I had no problem with this configuration for years
Now I'm deploying an update of these servers in a new ubuntu 18.04
server with openldap 2.4.47. In order to synchronize entries between
them, I have linked this new server to one of the other (and this one to
the new one).
Configuration in the new one (named canis41) is:
dn: olcDatabase={3}mdb,cn=config
...
olcSyncrepl: {0}rid=39 provider=ldap://canis39.um.es binddn=<repl user
dn> bindmethod=simple credentials=XXXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="60 +" timeout=1
schemache
cking=off scope=sub
olcSyncrepl: {1}rid=42 provider=ldap://canis42.um.es binddn=<repl user
dn> bindmethod=simple credentials=XXXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="30 +" timeout=1
logbase="
cn=log" logfilter="(&(objectClass=auditWriteObject)(reqResult=0))"
schemaCh
ecking=on syncdata=accesslog exattrs="pwdFailureTime"
dn: olcOverlay={0}syncprov,olcDatabase={3}mdb,cn=config
objectClass: olcSyncProvConfig
objectClass: olcOverlayConfig
objectClass: olcConfig
olcOverlay: {0}syncprov
olcSpCheckpoint: 100 10
olcSpSessionlog: 100
dn: olcOverlay={1}ppolicy,olcDatabase={3}mdb,cn=config
objectClass: olcPPolicyConfig
objectClass: olcOverlayConfig
objectClass: olcConfig
olcOverlay: {1}ppolicy
olcPPolicyDefault: cn=default,ou=policies,dc=Telematica
dn: olcOverlay={2}dynlist,olcDatabase={3}mdb,cn=config
objectClass: olcDynamicList
objectClass: olcOverlayConfig
objectClass: olcConfig
olcOverlay: {2}dynlist
olcDlAttrSet: {0}labeledURIObject labeledURI
where canis39 is one the former servers and canis42 is a new server too
synchronizing just with canis41.
My problem is that synchronization is working, but sometimes
modifications done in the canis3x farm are delayed a lot of time until
they are replicated to the new one (sometimes in the order of 40-60
minutes).
I'm logging sync logs, but I haven't found much information about these
logs. Is there any way to debug it? How?
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
11:26 a.m.
--On Monday, March 18, 2019 12:21 PM +0100 "Ángel L. Mateo" <amateo(a)um.es>
wrote:
I'm logging sync logs, but I haven't found much information
about these
logs. Is there any way to debug it? How?
Unfortunately, you've not really provided any actionable information, so
it's hard to say. I can say that I've had MMR deployments for years, using
delta-syncrepl without delay issues like you are reporting. There are
several examples of setting up N-way delta-syncrepl MMR servers in the
tests/data/regressions area, for example the regression tests for ITS8444
and ITS8800.
Regards,
Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
12:22 a.m.
El 20/3/19 a las 19:26, Quanah Gibson-Mount escribió:
--On Monday, March 18, 2019 12:21 PM +0100 "Ángel L. Mateo"
<amateo(a)um.es> wrote:
> I'm logging sync logs, but I haven't found much information about
> these
> logs. Is there any way to debug it? How?
Unfortunately, you've not really provided any actionable information, so
it's hard to say. I can say that I've had MMR deployments for years,
using delta-syncrepl without delay issues like you are reporting. There
are several examples of setting up N-way delta-syncrepl MMR servers in
the tests/data/regressions area, for example the regression tests for
ITS8444 and ITS8800.
I've been running MMR (not delta) for years too without problems too.
Now the server with problems works without problems for days, but then
it start delaying syncs.
The problem I have is that I don't know how to debug it.
Is there any documentation about how to debug it? about the sync logs
messages?
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
2:51 p.m.
--On Thursday, March 21, 2019 9:22 AM +0100 "Ángel L. Mateo"
<amateo(a)um.es> wrote:
I've been running MMR (not delta) for years too without problems
too.
Now the server with problems works without problems for days, but then
it start delaying syncs.
The problem I have is that I don't know how to debug it.
Is there any documentation about how to debug it? about the sync logs
messages?
I think one of the key differences to understand between syncrepl and
delta-syncrepl is that syncrepl will simply overwrite entries that have
discrepencies while delta-syncrepl will go into REFRESH mode. Since you
started out with an OpenLDAP version that has numerous replication bugs, it
may be your masters are not in accordance with one another, and the
"delays" you are seeing are actually systems going into refresh.
The first thing you should look at is if there are any instances of REFRESH
in your logs, something along the lines of:
do_syncrep2: rid=001 delta-sync lost sync, switching to REFRESH
If you see that, the issue isn't delayed replication, the issue is that
your databases are out of sync.
If you don't see instances of REFRESH mode being triggered in your log, we
can discuss further what the logs indicate and other things that may need
looking at.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
11:54 p.m.
El 21/3/19 a las 20:26, Michael Ströder escribió:
On 3/21/19 8:22 AM, Ángel L. Mateo wrote:
> Now the server with problems works without problems for days, but
> then it start delaying syncs.
How do you detect this?
Checking contextCSN attribute of all ldap servers. I get something like
this:
contextCSN: 20190322064915.077600Z#000000#01f#000000
contextCSN: 20190322065006.637604Z#000000#020#000000
contextCSN: 20190322065002.859879Z#000000#021#000000
contextCSN: 20190322065000.303715Z#000000#022#000000
contextCSN: 20190301102558.398349Z#000000#027#000000
contextCSN: 20190314080533.305657Z#000000#029#000000
There is one value for every server. When everything is ok, these
values are the same in all servers. But sometimes in the new server are
different, with values older than the in the others.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
12:01 a.m.
El 21/3/19 a las 22:51, Quanah Gibson-Mount escribió:
--On Thursday, March 21, 2019 9:22 AM +0100 "Ángel L.
Mateo"
<amateo(a)um.es> wrote:
> I've been running MMR (not delta) for years too without problems too.
>
> Now the server with problems works without problems for days, but
> then
> it start delaying syncs.
>
> The problem I have is that I don't know how to debug it.
>
> Is there any documentation about how to debug it? about the sync logs
> messages?
I think one of the key differences to understand between syncrepl and
delta-syncrepl is that syncrepl will simply overwrite entries that have
discrepencies while delta-syncrepl will go into REFRESH mode. Since you
started out with an OpenLDAP version that has numerous replication bugs,
it may be your masters are not in accordance with one another, and the
"delays" you are seeing are actually systems going into refresh.
replication is using syncrepl, not delta-syncrepl.
The first thing you should look at is if there are any instances of
REFRESH in your logs, something along the lines of:
do_syncrep2: rid=001 delta-sync lost sync, switching to REFRESH
If you see that, the issue isn't delayed replication, the issue is that
your databases are out of sync.
I can't find that exact message, but I have these in the consumer:
Mar 21 10:00:26 canis41 slapd[68402]: do_syncrep2: rid=039
LDAP_RES_INTERMEDIATE - REFRESH_PRESENT
Mar 21 10:40:56 canis41 slapd[68402]: do_syncrep2: rid=039
LDAP_RES_INTERMEDIATE - REFRESH_PRESENT
Mar 21 15:45:52 canis41 slapd[68402]: do_syncrep2: rid=039
LDAP_RES_INTERMEDIATE - REFRESH_PRESENT
If you don't see instances of REFRESH mode being triggered in
your log,
we can discuss further what the logs indicate and other things that may
need looking at.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
1:55 a.m.
El 21/3/19 a las 22:51, Quanah Gibson-Mount escribió:
The first thing you should look at is if there are any instances of
REFRESH in your logs, something along the lines of:
do_syncrep2: rid=001 delta-sync lost sync, switching to REFRESH
If you see that, the issue isn't delayed replication, the issue is that
your databases are out of sync.
Yesterday I had delays with replication and there was the refresh logs
I have already sent.
But now I'm having delays again (since 10min), but I don't have any
refresh log.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
9:19 a.m.
On 3/22/19 7:54 AM, Angel L. Mateo wrote:
El 21/3/19 a las 20:26, Michael Ströder escribió:
> On 3/21/19 8:22 AM, Ángel L. Mateo wrote:
>> Now the server with problems works without problems for days, but
>> then it start delaying syncs.
> How do you detect this?
>
Checking contextCSN attribute of all ldap servers. I get something
like this:
contextCSN: 20190322064915.077600Z#000000#01f#000000
contextCSN: 20190322065006.637604Z#000000#020#000000
contextCSN: 20190322065002.859879Z#000000#021#000000
contextCSN: 20190322065000.303715Z#000000#022#000000
contextCSN: 20190301102558.398349Z#000000#027#000000
contextCSN: 20190314080533.305657Z#000000#029#000000
There is one value for every server. When everything is ok, these
values are the same in all servers. But sometimes in the new server are
different, with values older than the in the others.
This is most times caused by an OpenLDAP bug. I see this quite often
with MMR providers even though the entries have been correctly
replicated to the other providers. Hence I asked for your detection method.
I've double-checked the code of my monitoring script very often!
And I'm not the only one seeing this false alarm in the monitoring.
E.g. two guys approached me after my OpenLDAP lightning monitoring talk
at FOSDEM reporting the same issue. And they use another monitoring tool.
So please check whether changes were correctly replicated instead.
Yes, that's nearly impossible if you have many changes on many entries.
I've considered to search the highest entryCSN value per provider ID
(server-side sorting on entryCSN, search limit 1) to compare it against
its accompanying contextCSN value. But during first superficial tests I
only got strange results. I have to investigate further before I can
come up with detailed results.
Ciao, Michael.
11:22 a.m.
--On Friday, March 22, 2019 9:01 AM +0100 "Angel L. Mateo" <amateo(a)um.es>
wrote:
replication is using syncrepl, not delta-syncrepl.
One of your quoted syncrepl stanzas clearly shows delta-syncrepl. I cannot
magically intuit which version you're having problems with.
olcSyncrepl: {1}rid=42 provider=ldap://canis42.um.es binddn=<repl user dn>
bindmethod=simple credentials=XXXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="30 +" timeout=1
logbase="
cn=log" logfilter="(&(objectClass=auditWriteObject)(reqResult=0))"
schemaCh
ecking=on syncdata=accesslog exattrs="pwdFailureTime"
^^^^^^^^^^^^^^^^
I can't find that exact message, but I have these in the
consumer:
Mar 21 10:00:26 canis41 slapd[68402]: do_syncrep2: rid=039
LDAP_RES_INTERMEDIATE - REFRESH_PRESENT
Mar 21 10:40:56 canis41 slapd[68402]: do_syncrep2: rid=039
LDAP_RES_INTERMEDIATE - REFRESH_PRESENT
Mar 21 15:45:52 canis41 slapd[68402]: do_syncrep2: rid=039
LDAP_RES_INTERMEDIATE - REFRESH_PRESENT
So that's not the same thing, and since you're not using delta-syncrepl you
wouldn't find the string I was asking about.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
11:23 a.m.
--On Friday, March 22, 2019 10:55 AM +0100 "Angel L. Mateo" <amateo(a)um.es>
wrote:
Yesterday I had delays with replication and there was the refresh
logs I
have already sent.
But now I'm having delays again (since 10min), but I don't have any
refresh log.
How are you determining that you have a delay?
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
11:35 a.m.
On 3/22/19 7:23 PM, Quanah Gibson-Mount wrote:
--On Friday, March 22, 2019 10:55 AM +0100 "Angel L.
Mateo"
<amateo(a)um.es> wrote:
> Yesterday I had delays with replication and there was the refresh
> logs I
> have already sent.
>
> But now I'm having delays again (since 10min), but I don't have any
> refresh log.
How are you determining that you have a delay?
He already responded that he's comparing contextCSN values.
See also my response. It's the usual monitoring-shows-contextCSN-diff
while replication just works. It's a bug I'm observing for years now.
Ciao, Michael.
12:41 p.m.
--On Friday, March 22, 2019 8:35 PM +0100 Michael Ströder
<michael(a)stroeder.com> wrote:
See also my response. It's the usual
monitoring-shows-contextCSN-diff
while replication just works. It's a bug I'm observing for years now.
It's not a bug.
syncprov-checkpoint <ops> <minutes>
After a write operation has succeeded, write the contextCSN
to
the underlying database if <ops> write operations or more
than
<minutes> time have passed since the last
checkpoint.
Checkpointing is disabled by default.
Note that he has a 10 minute interval set on the checkpoint:
olcSpCheckpoint: 100 10
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
1:05 p.m.
On 3/22/19 8:41 PM, Quanah Gibson-Mount wrote:
--On Friday, March 22, 2019 8:35 PM +0100 Michael Ströder
<michael(a)stroeder.com> wrote:
> See also my response. It's the usual monitoring-shows-contextCSN-diff
> while replication just works. It's a bug I'm observing for years now.
It's not a bug.
syncprov-checkpoint <ops> <minutes>
After a write operation has succeeded, write the
contextCSN to
the underlying database if <ops> write operations or more
than
<minutes> time have passed since the last
checkpoint.
Does that really mean that contextCSN value retrieved via LDAP are not
current? This would also break replication.
Up to now I understood that this option is similar to slapd-mdb's
checkpoint directive. Which means, the data retrieved via LDAP is
current but the DB files might not be fsynced yet.
Also in Æ-DIR the default is:
syncprov-checkpoint 1000 2
So according to the man-page you cited it means the gap must not be
greater than two minutes. But it's sometimes several hours and it lasts
for hours even if you write again something.
IMO it's simply a bug.
Ciao, Michael.
1:07 p.m.
--On Friday, March 22, 2019 10:05 PM +0100 Michael Ströder
<michael(a)stroeder.com> wrote:
So according to the man-page you cited it means the gap must not be
greater than two minutes. But it's sometimes several hours and it lasts
for hours even if you write again something.
IMO it's simply a bug.
I would suggest creating a repeatable test case and filing an ITS then,
since one generally does need to be able to validate existing contextCSNs
across a cluster. ;)
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
1:12 p.m.
On 3/22/19 9:07 PM, Quanah Gibson-Mount wrote:
--On Friday, March 22, 2019 10:05 PM +0100 Michael Ströder
<michael(a)stroeder.com> wrote:
> So according to the man-page you cited it means the gap must not be
> greater than two minutes. But it's sometimes several hours and it lasts
> for hours even if you write again something.
>
> IMO it's simply a bug.
I would suggest creating a repeatable test case and filing an ITS then,
since one generally does need to be able to validate existing
contextCSNs across a cluster. ;)
If it would be so easy I would have done it already.
There are no obvious conditions when this happens.
It just happens every now and then.
Ciao, Michael.
12:24 a.m.
El 22/3/19 a las 17:19, Michael Ströder escribió:
> Checking contextCSN attribute of all ldap servers. I get
something
> like this:
>
> contextCSN: 20190322064915.077600Z#000000#01f#000000
> contextCSN: 20190322065006.637604Z#000000#020#000000
> contextCSN: 20190322065002.859879Z#000000#021#000000
> contextCSN: 20190322065000.303715Z#000000#022#000000
> contextCSN: 20190301102558.398349Z#000000#027#000000
> contextCSN: 20190314080533.305657Z#000000#029#000000
>
> There is one value for every server. When everything is ok, these
> values are the same in all servers. But sometimes in the new server are
> different, with values older than the in the others.
This is most times caused by an OpenLDAP bug. I see this quite often
with MMR providers even though the entries have been correctly
replicated to the other providers. Hence I asked for your detection method.
I don't know if there is or not a bug related with this (I didn't have
any false alert for my running farm), but when I have this alert, then I
checked for latest changes (got from accesslog) and they aren't
replicated. So the delay is really happening.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
12:28 a.m.
El 22/3/19 a las 19:23, Quanah Gibson-Mount escribió:
--On Friday, March 22, 2019 10:55 AM +0100 "Angel L. Mateo"
<amateo(a)um.es> wrote:
> Yesterday I had delays with replication and there was the refresh
> logs I
> have already sent.
>
> But now I'm having delays again (since 10min), but I don't have any
> refresh log.
How are you determining that you have a delay?
I manually get changes from accesslog database (of provider ldap
server) and look for them in the consumer ldap.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
12:34 a.m.
El 22/3/19 a las 19:22, Quanah Gibson-Mount escribió:
--On Friday, March 22, 2019 9:01 AM +0100 "Angel L. Mateo"
<amateo(a)um.es> wrote:
> replication is using syncrepl, not delta-syncrepl.
One of your quoted syncrepl stanzas clearly shows delta-syncrepl. I
cannot magically intuit which version you're having problems with.
olcSyncrepl: {1}rid=42 provider=ldap://canis42.um.es binddn=<repl user
dn> bindmethod=simple credentials=XXXXXXXX searc
hbase=dc=Telematica type=refreshAndPersist retry="30 +" timeout=1
logbase="
cn=log" logfilter="(&(objectClass=auditWriteObject)(reqResult=0))"
schemaCh
ecking=on syncdata=accesslog exattrs="pwdFailureTime"
Maybe I haven't clearly explain the scenario.
* I have a farm with syncrepl running for years without any problem.
This farm is running 2.4.43. Servers of this farm are named canis3x
* I have a new farm with servers named canis41 and canis42 (with
2.4.47), where:
** canis41 is syncrepl with canis39 (to keep both farms synchronized)
** canis41 and canis42 has delta-syncrepl between them (my idea is to
switch off canis3x farm and then left just this delta-syncrepl)
The problem I'm having is with syncrepl between canis39 and canis41.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
12:44 a.m.
El 25/3/19 a las 8:28, Ángel L. Mateo escribió:
El 22/3/19 a las 19:23, Quanah Gibson-Mount escribió:
>
> How are you determining that you have a delay?
>
I manually get changes from accesslog database (of provider ldap
server) and look for them in the consumer ldap.
To be honest, when I conextCSN are not synchronized, then I check
entryCSN for entries recently changed.
And I don't know if it could be a problem with syncprov-checkpoint,
but, as I understand, this is a parameter for the provider, then the
provider could have changes not writed to its contextCSN, but then it
writes them, all consumer should have this value replicated, shouldn't it?
In my scenario, all canis3x have the same contextCSN attributes (so
they have consolidated them), but canis41 hasn't sync them.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
11:56 a.m.
--On Monday, March 25, 2019 9:34 AM +0100 "Ángel L. Mateo" <amateo(a)um.es>
wrote:
* I have a farm with syncrepl running for years without any problem.
This
farm is running 2.4.43. Servers of this farm are named canis3x
* I have a new farm with servers named canis41 and canis42 (with 2.4.47),
where:
** canis41 is syncrepl with canis39 (to keep both farms synchronized)
** canis41 and canis42 has delta-syncrepl between them (my idea is to
switch off canis3x farm and then left just this delta-syncrepl)
The problem I'm having is with syncrepl between canis39 and canis41.
None of your configurations set a keepalive. If you have any sort of load
balancer/switch in between, they will often cut idle connections, and
replication will stop until slapd is restarted.
I recommend always defining a keepalive interval in the syncrepl stanza to
avoid these types of issues.
keepalive=240:10:30
usually works well, unless the device is configured to close idle
connections at less than a 5 minute interval.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
11:58 p.m.
New subject: Antw: Re: Replication delay
>> Quanah Gibson-Mount <quanah(a)symas.com> schrieb am
25.03.2019 um 19:56 in
Nachricht <CF0FD0042D3D17C49C943E62(a)[192.168.1.39]>:
--On Monday, March 25, 2019 9:34 AM +0100 "Ángel L. Mateo"
<amateo(a)um.es>
wrote:
> * I have a farm with syncrepl running for years without any problem. This
> farm is running 2.4.43. Servers of this farm are named canis3x
> * I have a new farm with servers named canis41 and canis42 (with 2.4.47),
> where:
> ** canis41 is syncrepl with canis39 (to keep both farms synchronized)
> ** canis41 and canis42 has delta-syncrepl between them (my idea is to
> switch off canis3x farm and then left just this delta-syncrepl)
>
> The problem I'm having is with syncrepl between canis39 and canis41.
None of your configurations set a keepalive. If you have any sort of load
balancer/switch in between, they will often cut idle connections, and
replication will stop until slapd is restarted.
I recommend always defining a keepalive interval in the syncrepl stanza to
avoid these types of issues.
keepalive=240:10:30
usually works well, unless the device is configured to close idle
connections at less than a 5 minute interval.
Hi!
I don't understand that: Keepalive (as I know it) has nothing to do with idle
connections, but only with dead connections. And what's the magic with 5
minutes?
Regards,
Ulrich
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
6:59 a.m.
New subject: Antw: Re: Replication delay
Am 26.03.19 um 07:58 schrieb Ulrich Windl:
I don't understand that: Keepalive (as I know it) has nothing to
do with idle
connections, but only with dead connections.
Any statefull firewall will
reset/drop/delete/discard a connections state information
from it's internal connection table after some time if no traffic was seen (for
example for 5 minutes)
Andreas
7:06 a.m.
New subject: Antw: Re: Replication delay
--On Tuesday, March 26, 2019 8:58 AM +0100 Ulrich Windl
<Ulrich.Windl(a)rz.uni-regensburg.de> wrote:
> I recommend always defining a keepalive interval in the syncrepl
stanza
> to avoid these types of issues.
>
> keepalive=240:10:30
>
> usually works well, unless the device is configured to close idle
> connections at less than a 5 minute interval.
Hi!
I don't understand that: Keepalive (as I know it) has nothing to do with
idle connections, but only with dead connections. And what's the magic
with 5 minutes?
Hello,
You're understanding is generally incorrect. The paramater is called "keep
alive" and not "kill dead" for a reason. When using refreshAndPersist
connections in an environment where you have a traffic device (such as an
F5), the devices are often configured to terminate idle connections after
some period of time (which often defaults to 5 minutes). By configuring a
keepalive in the syncrepl stanza, the connection appears "alive" to the
traffic device even if there is no replication traffic occurring. Thus
"keep alive".
There is a *secondary* benefit, in that it does also allow slapd to detect
if a connection was severed, and so re-establish a new connection in that
case, but the primary purpose is to keep it from ever getting severed in
the first place.
If you have no "keepalive" set, and the traffic device severs the
connection, slapd cannot detect this, and will think it's still connected
and no replication will occur until slapd is restarted.
I.e., the primary purpose is to keep the connection alive.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
9:30 a.m.
New subject: Antw: Re: Replication delay
>> "A. Schulze" <sca(a)andreasschulze.de> schrieb
am 26.03.2019 um 14:59 in
Nachricht
<89c3ef23-e670-d4ae-a189-74135643c014(a)andreasschulze.de>:
Am 26.03.19 um 07:58 schrieb Ulrich Windl:
> I don't understand that: Keepalive (as I know it) has nothing to do with
idle
> connections, but only with dead connections.
Any statefull firewall will reset/drop/delete/discard a connections state
information
from it's internal connection table after some time if no traffic was seen
(for example for 5 minutes)
Actually a bad idea: A few years again I wrote a TCP redirector that had problems:
First, I had no timeout, so dead connections could not be detected, so I added a timeout.
Second, idle connections timed out, so I added keep-alive.
Then I was happy.
It seems LDAP connections here also live for a very long time, sometimes idle for
hours...
Regards,
Ulrich
12:24 a.m.
New subject: Antw: Re: Replication delay
Although I'm not using any intermediate device between ldap servers
(they all are in the same network) I have added the keepalive option to
syncrepl, without any result.
El 26/3/19 a las 15:06, Quanah Gibson-Mount escribió:
--On Tuesday, March 26, 2019 8:58 AM +0100 Ulrich Windl
<Ulrich.Windl(a)rz.uni-regensburg.de> wrote:
>> I recommend always defining a keepalive interval in the syncrepl stanza
>> to avoid these types of issues.
>>
>> keepalive=240:10:30
>>
>> usually works well, unless the device is configured to close idle
>> connections at less than a 5 minute interval.
>
> Hi!
>
> I don't understand that: Keepalive (as I know it) has nothing to do with
> idle connections, but only with dead connections. And what's the magic
> with 5 minutes?
Hello,
You're understanding is generally incorrect. The paramater is called
"keep alive" and not "kill dead" for a reason. When using
refreshAndPersist connections in an environment where you have a traffic
device (such as an F5), the devices are often configured to terminate
idle connections after some period of time (which often defaults to 5
minutes). By configuring a keepalive in the syncrepl stanza, the
connection appears "alive" to the traffic device even if there is no
replication traffic occurring. Thus "keep alive".
There is a *secondary* benefit, in that it does also allow slapd to
detect if a connection was severed, and so re-establish a new connection
in that case, but the primary purpose is to keep it from ever getting
severed in the first place.
If you have no "keepalive" set, and the traffic device severs the
connection, slapd cannot detect this, and will think it's still
connected and no replication will occur until slapd is restarted.
I.e., the primary purpose is to keep the connection alive.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
10:49 a.m.
New subject: Antw: Re: Replication delay
--On Wednesday, March 27, 2019 9:24 AM +0100 "Ángel L. Mateo"
<amateo(a)um.es> wrote:
Although I'm not using any intermediate device between ldap
servers
(they all are in the same network) I have added the keepalive option to
syncrepl, without any result.
Yeah, it's more of a safeguard to ensure one avoids those types of issues.
As for your current situation, I did have a customer the other day who was
reporting multi-hour replication delays. But when I looked into it, the
issue was not unexpected. I don't know if this has any relevance to your
situation, but here is what they were doing.
They had a 4-way MMR setup. They were doing 50k ADDs to each of the
masters. This is one of the worst things one could do, becuase it will
massively slow down replication and cause all the servers to get behind due
to the contention caused by the massive number of ADD ops occurring on each
server while also trying to replicate the ADDs from the other servers.
I.e., the best route would be to simply ADD all 150k entries to a single
member node and let them replicate out from there.
You've noted before wanting some information on what replication lines
mean. It's hard to answer that exactly, as what's important to examine and
what isn't important can be difficult to determine without looking at the
actual logs and having some knowledge of what's going on, but this may be
of some help. Here are some different sets of logs and scenarios. All
logs, etc, are based on delta-syncrepl being in use.
Scenario #1:
Skipping an change that's too far in the past. This should have been
processed already from the original change on the original master (SID
066). This change request came from SID 0c9
Mar 25 12:19:23 master1 slapd[29939]: do_syncrep2: rid=201
cookie=rid=201,sid=0c9,csn=20190325191922.072386Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: do_syncrep2: rid=201 CSN too old,
ignoring 20190325191922.072386Z#000000#066#000000
(reqStart=20190325191922.000185Z,cn=deltalog)
Scenario #2:
Applying a change that originated on another server:
Mar 25 12:19:23 master1 slapd[29939]: do_syncrep2: rid=102
cookie=rid=102,sid=066,csn=20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: slap_queue_csn: queueing
0x7f9ab88ce0f0 20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: syncrepl_message_to_op: rid=102 tid
bcffc700
Mar 25 12:19:23 master1 slapd[29939]: slap_queue_csn: queueing
0x7f9ab842eda0 20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: syncprov_sendresp: to=12d,
cookie=rid=101,sid=065,csn=20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: syncprov_matchops: skipping original
sid 066
Mar 25 12:19:23 master1 slapd[29939]: slap_graduate_commit_csn: removing
0x7f9ab842eda0 20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: slap_graduate_commit_csn: removing
0x7f9ab88ce0f0 20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: syncprov_sendresp: to=0c9,
cookie=rid=101,sid=065,csn=20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: syncrepl_message_to_op: rid=102
be_add
cn=QA_MACHINE_9F06E7769C9B49B49D737414662C9089,ou=machines,dc=example,dc=com
(0)
Mar 25 12:19:23 master1 slapd[29939]: slap_queue_csn: queueing
0x7f9ab8a3b930 20190325191923.177761Z#000000#066#000000
Mar 25 12:19:23 master1 slapd[29939]: slap_graduate_commit_csn: removing
0x7f9ab8a3b930 20190325191923.177761Z#000000#066#000000
So in the above, this master (SID065) got a change from another master
(SID066). It was not a change it had received yet from 066, so it applies
it. It skips sending this change back to the originating server (Thus the
"skipping original sid 066" line). It forwards the change to its other
listeners (0c9, 12d) in case they do not have a direct link to 066, and
commits the change locally.
Scenario #3:
Originating a change:
Mar 25 03:58:24 master1 slapd[29939]: conn=5788689 op=75 ADD dn="cn=ATOM
Virtual:843a4b737992,ou=identities,dc=example,dc=com"
Mar 25 03:58:24 master1 slapd[29939]: slap_queue_csn: queueing
0x7f9ab053ed40 20190325105824.517526Z#000000#065#000000
Mar 25 03:58:24 master1 slapd[29939]: slap_queue_csn: queueing
0x7f9ab106c0f0 20190325105824.517526Z#000000#065#000000
Mar 25 03:58:24 master1 slapd[29939]: syncprov_sendresp: to=12d,
cookie=rid=101,sid=065,csn=20190325105824.517526Z#000000#065#000000
Mar 25 03:58:24 master1 slapd[29939]: syncprov_sendresp: to=0c9,
cookie=rid=101,sid=065,csn=20190325105824.517526Z#000000#065#000000
Mar 25 03:58:24 master1 slapd[29939]: syncprov_sendresp: to=066,
cookie=rid=101,sid=065,csn=20190325105824.517526Z#000000#065#000000
Mar 25 03:58:24 master1 slapd[29939]: slap_graduate_commit_csn: removing
0x7f9ab106c0f0 20190325105824.517526Z#000000#065#000000
Mar 25 03:58:24 master1 slapd[29939]: conn=5788689 op=75 RESULT tag=105
err=0 text=
Mar 25 03:58:24 master1 slapd[29939]: slap_graduate_commit_csn: removing
0x7f9ab053ed40 20190325105824.517526Z#000000#065#000000
So in the above, the master originating this change (065) creates the
relevant CSN and forwards this change to its listeners (SIDs 12d, 0c9,
066), commits, and cleans up.
To read a CSN value:
20190325105824.517526Z#000000#065#000000
The first part is the time (Zulu) that the change occured. So in above
case, the change occurred at:
2019/03/25 @ 10:58:24.517526 seconds Zulu time (Server time as we see above
was 03:58:24), so this server is 7 hours behind Zulu time.
The server where the modification was made was the one with a SID value of
065.
If you're looking at the contextCSN values on a server, it essentially
tells you the last change it processed from each master that it talks to
(and its own current change value). If the values aren't matching between
servers, then you need to see if those servers are still processing changes
from the other masters.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
11:40 p.m.
New subject: Antw: Re: Replication delay
El 29/3/19 a las 18:49, Quanah Gibson-Mount escribió:
--On Wednesday, March 27, 2019 9:24 AM +0100 "Ángel L.
Mateo"
<amateo(a)um.es> wrote:
> Although I'm not using any intermediate device between ldap servers
> (they all are in the same network) I have added the keepalive option to
> syncrepl, without any result.
Yeah, it's more of a safeguard to ensure one avoids those types of issues.
As for your current situation, I did have a customer the other day who
was reporting multi-hour replication delays. But when I looked into it,
the issue was not unexpected. I don't know if this has any relevance to
your situation, but here is what they were doing.
They had a 4-way MMR setup. They were doing 50k ADDs to each of the
masters. This is one of the worst things one could do, becuase it will
massively slow down replication and cause all the servers to get behind
due to the contention caused by the massive number of ADD ops occurring
on each server while also trying to replicate the ADDs from the other
servers. I.e., the best route would be to simply ADD all 150k entries to
a single member node and let them replicate out from there.
In my case I'm not doing massive ADDs. The only modification I could
have is related with password policy overlay in a >40k users directory.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
3:03 p.m.
New subject: Antw: Re: Replication delay
--On Monday, April 01, 2019 9:40 AM +0200 "Ángel L. Mateo" <amateo(a)um.es>
wrote:
In my case I'm not doing massive ADDs. The only modification I
could
have is related with password policy overlay in a >40k users directory.
Hi,
Unfortunately there's been near zero information provided that's actionable
on this end, so unless you're willing to be more forthcoming, there's not
really any additional assistance I can provide.
Regards,
Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
4:53 a.m.
El 25/3/19 a las 19:56, Quanah Gibson-Mount escribió:
None of your configurations set a keepalive. If you have any sort of
load balancer/switch in between, they will often cut idle connections,
and replication will stop until slapd is restarted.
I recommend always defining a keepalive interval in the syncrepl stanza
to avoid these types of issues.
keepalive=240:10:30
usually works well, unless the device is configured to close idle
connections at less than a 5 minute interval.
Finally, it seems that the problem could be related with conections
being closed, although I don't have any network device between servers.
I have found messages like:
Apr 3 14:31:48 canis41 slapd[122414]: conn=211822 fd=21 closed
(idletimeout)
in my logs for replica connections.
I tried to configure keepalive when you suggested it, but I configured
it in just one connection of the replica.
Now I have configured it in both consumers and since (yesterday) then I
have no connections closed neither replica delays.
Now I have to find why my system is closing these connections. The
difference between the old farm and this new server is the ubuntu
version (from 14.04 to 18.04). I don't know if systemd (used in ubuntu
18.04) could be the reason.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
7:32 a.m.
--On Thursday, April 04, 2019 2:53 PM +0200 "Ángel L. Mateo"
<amateo(a)um.es> wrote:
Apr 3 14:31:48 canis41 slapd[122414]: conn=211822 fd=21 closed
(idletimeout)
in my logs for replica connections.
This indicates that there is an "idletimeout" directive configured and that
the "limits" directive has not been configured for the replication DN to by
pass that limit. The replication DN generally should not be subject to
time or size limits.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
8:22 a.m.
Quanah Gibson-Mount wrote:
--On Thursday, April 04, 2019 2:53 PM +0200 "Ángel L.
Mateo" <amateo(a)um.es> wrote:
> Apr 3 14:31:48 canis41 slapd[122414]: conn=211822 fd=21 closed
> (idletimeout)
>
> in my logs for replica connections.
This indicates that there is an "idletimeout" directive configured and that the
"limits" directive has not been configured for the replication DN to by pass
that limit. The replication DN generally should not be subject to time or size limits.
slapd doesn't enforce idletimeout on syncrepl connections. If that message is showing
up
it must be for some other connection. But if setting keepalive fixes the issue, that
still
implies that something in the network layer is not forwarding traffic as it should.
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
11:26 p.m.
El 4/4/19 a las 16:32, Quanah Gibson-Mount escribió:
--On Thursday, April 04, 2019 2:53 PM +0200 "Ángel L.
Mateo"
<amateo(a)um.es> wrote:
> Apr 3 14:31:48 canis41 slapd[122414]: conn=211822 fd=21 closed
> (idletimeout)
>
> in my logs for replica connections.
This indicates that there is an "idletimeout" directive configured and
that the "limits" directive has not been configured for the replication
DN to by pass that limit. The replication DN generally should not be
subject to time or size limits.
I have an idletimeout directive:
dn: cn=config
olcIdleTimeout: 600
but I also have the lits directive for replica user:
olcLimits: {6}dn.exact=cn=Replica,ou=People,ou=Management,o=SlapdRoot
size.hard=unlimited size.soft=unlimited time.hard=unlimited
time.soft=unlimited
so, according to Howard Chu, its must be another reason.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
6:23 a.m.
--On Friday, April 05, 2019 9:26 AM +0200 "Angel L. Mateo" <amateo(a)um.es>
wrote:
dn: cn=config
olcIdleTimeout: 600
but I also have the lits directive for replica user:
olcLimits: {6}dn.exact=cn=Replica,ou=People,ou=Management,o=SlapdRoot
size.hard=unlimited size.soft=unlimited time.hard=unlimited
time.soft=unlimited
so, according to Howard Chu, its must be another reason.
Yes, apparently so. But it wouldn't be something on the OpenLDAP side
that's causing the connections to be broken. I'm glad setting the
keepalive parameter resolved the issue.
--Quanah
--
Quanah Gibson-Mount
Product Architect
Symas Corporation
Packaged, certified, and supported LDAP solutions powered by OpenLDAP:
<http://www.symas.com>
11:04 p.m.
El 5/4/19 a las 15:23, Quanah Gibson-Mount escribió:
--On Friday, April 05, 2019 9:26 AM +0200 "Angel L. Mateo"
<amateo(a)um.es> wrote:
> dn: cn=config
> olcIdleTimeout: 600
>
> but I also have the lits directive for replica user:
>
> olcLimits: {6}dn.exact=cn=Replica,ou=People,ou=Management,o=SlapdRoot
> size.hard=unlimited size.soft=unlimited time.hard=unlimited
> time.soft=unlimited
>
> so, according to Howard Chu, its must be another reason.
Yes, apparently so. But it wouldn't be something on the OpenLDAP side
that's causing the connections to be broken.
The only difference between old servers and the new one, besides
openldap version, is the version of the OS (ubuntu 14.04 vs ubuntu
18.04). I'm looking form something in the os closing idle connections,
but I can't find it.
--
Angel L. Mateo Martínez
Sección de Telemática
Área de Tecnologías de la Información
y las Comunicaciones Aplicadas (ATICA)
http://www.um.es/atica
Tfo: 868889150
Fax: 868888337
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days inactive
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openldap-technical@openldap.org
34 comments
7 participants
participants (7)
-
A. Schulze -
Angel L. Mateo -
Howard Chu -
Michael Ströder -
Quanah Gibson-Mount -
Ulrich Windl -
Ángel L. Mateo