2:16 a.m.
Hi all,
I am also doing some testing with mdb at the moment, and my initial testing indicates that
mdb is faster for reads but slower for writes than bdb.
I am using openldap 2.4.32 on centos 6, on a 24 core box with 132 Gb RAM.
My test directory has ~ 3 million entries, and I loaded it into mdb using slapadd which
took over 2 days (by comparison, the same load into bdb takes 2-3 hours).
(as an aside, I initially tried using 2.4.31, but slapadd crashed after having loaded
about 90% of the data, and this was repeatable).
On disk the directory takes up ~ 13 Gb for mdb and ~ 18Gb for bdb.
Cache size for bdb is set to 63 Gb in DB_CONFIG.
Directory size for mdb is set to 63 Gb
Adding 120000 entries from an ldif file using ldapadd took ~ 10 minutes for mdb and ~ 2
minutes for bdb.
Deleting 120000 entries using ldapdelete took ~ 10 minutes for mdb and ~ 3 minutes for
bdb
A search returning ~ 300000 DNs took ~ 6 seconds for mdb and for bdb it took ~ 6 minutes
from a cold start of slapd and then ~ 35 seconds.
Chris
5:52 a.m.
New subject: Performance of MDB and BDB Please suggest?
Chris Card wrote:
Hi all,
I am also doing some testing with mdb at the moment, and my initial
testing
indicates that mdb is faster for reads but slower for writes than bdb.
This is generally true, and is documented in the papers I've published on the
subject.
I am using openldap 2.4.32 on centos 6, on a 24 core box with 132 Gb
RAM.
My test directory has ~ 3 million entries, and I loaded it into mdb
using
slapadd which took over 2 days (by comparison, the same load into bdb takes
2-3 hours).
(as an aside, I initially tried using 2.4.31, but slapadd crashed
after
having loaded about 90% of the data, and this was repeatable).
This is not normal. With slapadd -q MDB is faster than BDB assuming you're
using a decent filesystem and sensible mount options. JFS, EXT2, do better
than other filesystems in my tests. Very recent EXT4 may be better than EXT3
as well.
On disk the directory takes up ~ 13 Gb for mdb and ~ 18Gb for bdb.
Cache
size for bdb is set to 63 Gb in DB_CONFIG. Directory size for mdb is set to
63 Gb
The relative sizes sound right.
Adding 120000 entries from an ldif file using ldapadd took ~ 10
minutes
for
mdb and ~ 2 minutes for bdb.
Deleting 120000 entries using ldapdelete took ~ 10 minutes for mdb
and ~ 3
minutes for bdb
Again, this is filesystem dependent, but basically right. If you're doing a
purely serial test, however, you're not seeing the true picture. With multiple
concurrent writers, BDB's throughput will degrade (due to transaction
deadlocks) while MDB's will remain constant. Again, this is documented in the
published papers on MDB.
MDB's write speed on my tests generally remains constant with a standard
deviation of essentially zero under all load conditions. BDB's write speed
will degrade under heavy load (to slower than MDB) and the standard deviation
widens as load increases.
A search returning ~ 300000 DNs took ~ 6 seconds for mdb and for bdb
it
took
~ 6 minutes from a cold start of slapd and then ~ 35 seconds.
Sounds right. MDB's cold start overhead is measurable but essentially zero.
Chris
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
6:07 a.m.
New subject: Performance of MDB and BDB Please suggest?
Chris Card wrote:
>
> I am using openldap 2.4.32 on centos 6, on a 24 core box with
132 Gb RAM.
> My test directory has ~ 3 million entries, and I loaded it into mdb using
slapadd which took over 2 days (by comparison, the same load into bdb takes
2-3 hours).
> (as an aside, I initially tried using 2.4.31, but slapadd crashed after
having loaded about 90% of the data, and this was repeatable).
This is not normal. With slapadd -q MDB is faster than BDB assuming you're
using a decent filesystem and sensible mount options. JFS, EXT2, do better
than other filesystems in my tests. Very recent EXT4 may be better than EXT3
as well.
The filesystem is xfs, mounted as a drbd device (although at the moment
the other
half of the drbd pair is not configured, so it doesn't have to wait for synchronous
writes across the network)
> Chris
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
6:47 a.m.
New subject: Performance of MDB and BDB Please suggest?
Chris Card wrote:
> Chris Card wrote:
>>
>> I am using openldap 2.4.32 on centos 6, on a 24 core box with 132 Gb RAM.
>
>> My test directory has ~ 3 million entries, and I loaded it into mdb using
> slapadd which took over 2 days (by comparison, the same load into bdb takes
> 2-3 hours).
> This is not normal. With slapadd -q MDB is faster than BDB
assuming you're
> using a decent filesystem and sensible mount options. JFS, EXT2, do better
> than other filesystems in my tests. Very recent EXT4 may be better than EXT3
> as well.
The filesystem is xfs, mounted as a drbd device (although at the moment the other
half of the drbd pair is not configured, so it doesn't have to wait for synchronous
writes across the network)
Sounds like you're not using slapadd -q. Either that, or your filesystem cache
settings are way off.
Your system has enough RAM to hold the entire DB in the filesystem cache. The
speed you're reporting indicates that it's not doing so. As another sanity
check, look at slapadd -q with the DB on a tmpfs. With correct FS cache
settings, the performance delta between tmpfs and a real disk should only be a
few percent.
The important sysctl settings on a Linux system are
vm.dirty_writeback_centisecs
vm.dirty_expire_centisecs
vm.dirty_ratio
vm.dirty_background_ratio
Note that ext3/ext4 have their own writeback timer, which overrides the sysctl
settings, so you need to set theirs at mount time.
The defaults for these settings tend to be low on most Linux systems; their
tuning is aimed at machines that are essentially memory-starved so they flush
the caches before they get very full. The net effect of this is that even
though some userland code performs asynchronous writes, they are effectively
synchronous because the OS flushes them out almost immediately. slapadd -q
attempts to perform asynchronous writes but it's nullified as a result of
these settings.
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
7:05 a.m.
New subject: Performance of MDB and BDB Please suggest?
>>> I am using openldap 2.4.32 on centos 6, on a 24 core box
with 132 Gb RAM.
>>
>>> My test directory has ~ 3 million entries, and I loaded it into mdb using
>> slapadd which took over 2 days (by comparison, the same load into bdb takes
>> 2-3 hours).
>> This is not normal. With slapadd -q MDB is faster than BDB assuming you're
>> using a decent filesystem and sensible mount options. JFS, EXT2, do better
>> than other filesystems in my tests. Very recent EXT4 may be better than EXT3
>> as well.
> The filesystem is xfs, mounted as a drbd device (although at the moment the other
> half of the drbd pair is not configured, so it doesn't have to wait for
synchronous
> writes across the network)
Sounds like you're not using slapadd -q. Either that, or your filesystem cache
Oh ****! You're quite right, I managed to lose the -q from the slapadd command when
copy/pasting
from a script. I'll try running it again with -q.
Do you have an ETA for improvements to mdb write performance?
Chris
7:57 a.m.
New subject: Performance of MDB and BDB Please suggest?
On Aug 24, 2012, at 7:19 AM, Chris Card <ctcard(a)hotmail.com> wrote:
>>>> I am using openldap 2.4.32 on centos 6, on a 24 core box with 132 Gb
RAM.
>>>
>>>> My test directory has ~ 3 million entries, and I loaded it into mdb
using
>>> slapadd which took over 2 days (by comparison, the same load into bdb takes
>>> 2-3 hours).
>
>>> This is not normal. With slapadd -q MDB is faster than BDB assuming
you're
>>> using a decent filesystem and sensible mount options. JFS, EXT2, do better
>>> than other filesystems in my tests. Very recent EXT4 may be better than EXT3
>>> as well.
>> The filesystem is xfs, mounted as a drbd device (although at the moment the
other
>> half of the drbd pair is not configured, so it doesn't have to wait for
synchronous
>> writes across the network)
>
> Sounds like you're not using slapadd -q. Either that, or your filesystem cache
Oh ****! You're quite right, I managed to lose the -q from the slapadd command when
copy/pasting
from a script. I'll try running it again with -q.
Do you have an ETA for improvements to mdb write performance?
Chris
In my testing, only a setting of "2" for tool threads when using MDB with
slapadd made sense. Any higher value degraded perf. Also, current RE24 has one write
perf change in it from Howard over 2.4.32 although I have not yet tested its impact any.
It made some differences for Howard in his tests.
--Quanah
11:16 a.m.
New subject: Performance of MDB and BDB Please suggest?
Chris Card wrote:
>>>> I am using openldap 2.4.32 on centos 6, on a 24 core box with 132 Gb
RAM.
>>>
>>>> My test directory has ~ 3 million entries, and I loaded it into mdb
using
>>> slapadd which took over 2 days (by comparison, the same load into bdb takes
>>> 2-3 hours).
>
>>> This is not normal. With slapadd -q MDB is faster than BDB assuming
you're
>>> using a decent filesystem and sensible mount options. JFS, EXT2, do better
>>> than other filesystems in my tests. Very recent EXT4 may be better than EXT3
>>> as well.
>> The filesystem is xfs, mounted as a drbd device (although at the moment the
other
>> half of the drbd pair is not configured, so it doesn't have to wait for
synchronous
>> writes across the network)
>
> Sounds like you're not using slapadd -q. Either that, or your filesystem cache
Oh ****! You're quite right, I managed to lose the -q from the slapadd command when
copy/pasting
from a script. I'll try running it again with -q.
Do you have an ETA for improvements to mdb write performance?
Not at this point. There are several approaches to test; most of them will
probably be dead ends.
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
2:07 a.m.
New subject: Performance of MDB and BDB Please suggest?
Hi ,
Chirs and Howard,
Please share the slapd.conf for MDB for which you have done the performance
testing..
BR's,
Haroon
On Fri, Aug 24, 2012 at 11:46 PM, Howard Chu <hyc(a)symas.com> wrote:
Chris Card wrote:
>
>
>
>>>>> I am using openldap 2.4.32 on centos 6, on a 24 core box with 132
Gb
RAM.
>>>>
>>>>> My test directory has ~ 3 million entries, and I loaded it into mdb
using
>>>> slapadd which took over 2 days (by comparison, the same load into bdb
takes
>>>> 2-3 hours).
>>
>>>> This is not normal. With slapadd -q MDB is faster than BDB assuming
you're
>>>> using a decent filesystem and sensible mount options. JFS, EXT2, do
better
>>>> than other filesystems in my tests. Very recent EXT4 may be better
than EXT3
>>>> as well.
>>> The filesystem is xfs, mounted as a drbd device (although at the
moment the other
>>> half of the drbd pair is not configured, so it doesn't have to wait
for synchronous
>>> writes across the network)
>>
>> Sounds like you're not using slapadd -q. Either that, or your
filesystem cache
>
> Oh ****! You're quite right, I managed to lose the -q from the slapadd
command when copy/pasting
> from a script. I'll try running it again with -q.
>
> Do you have an ETA for improvements to mdb write performance?
Not at this point. There are several approaches to test; most of them will
probably be dead ends.
--
-- Howard Chu
CTO, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
4:59 a.m.
New subject: Performance of MDB and BDB Please suggest?
Dear Experts,
Today we tried with to run the load with the below schema. We added about
.6M entries in the DB.
Still our performance is severely poor. (10 TPS)
Can anybody review our slapd.conf file and point us where we are wrong, is
there any other config we have missed out.
System we have is 64 bit 12 core machine RHEL having total memory of
49418952 kB.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dn: dc=example,dc=com
objectClass: dcObject
objectClass: organization
o: Example Company
dc: example
dn: cn=Manager0,dc=example,dc=com
objectClass: organizationalRole
cn: Manager0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
Thanks and Regards
Yajuvendra
Insanity: D*oing* the same *thing* over and over *again and expecting*
different
results. Albert Einstein
On Sat, Aug 25, 2012 at 2:37 PM, aryan rawat <aryanrawat24(a)gmail.com> wrote:
Hi ,
Chirs and Howard,
Please share the slapd.conf for MDB for which you have done the
performance testing..
BR's,
Haroon
On Fri, Aug 24, 2012 at 11:46 PM, Howard Chu <hyc(a)symas.com> wrote:
> Chris Card wrote:
> >
> >
> >
> >>>>> I am using openldap 2.4.32 on centos 6, on a 24 core box with
132
> Gb RAM.
> >>>>
> >>>>> My test directory has ~ 3 million entries, and I loaded it into
mdb
> using
> >>>> slapadd which took over 2 days (by comparison, the same load into
> bdb takes
> >>>> 2-3 hours).
> >>
> >>>> This is not normal. With slapadd -q MDB is faster than BDB assuming
> you're
> >>>> using a decent filesystem and sensible mount options. JFS, EXT2, do
> better
> >>>> than other filesystems in my tests. Very recent EXT4 may be better
> than EXT3
> >>>> as well.
> >>> The filesystem is xfs, mounted as a drbd device (although at the
> moment the other
> >>> half of the drbd pair is not configured, so it doesn't have to wait
> for synchronous
> >>> writes across the network)
> >>
> >> Sounds like you're not using slapadd -q. Either that, or your
> filesystem cache
> >
> > Oh ****! You're quite right, I managed to lose the -q from the slapadd
> command when copy/pasting
> > from a script. I'll try running it again with -q.
> >
> > Do you have an ETA for improvements to mdb write performance?
>
> Not at this point. There are several approaches to test; most of them will
> probably be dead ends.
>
> --
> -- Howard Chu
> CTO, Symas Corp. http://www.symas.com
> Director, Highland Sun http://highlandsun.com/hyc/
> Chief Architect, OpenLDAP http://www.openldap.org/project/
>
>
7:49 a.m.
New subject: Performance of MDB and BDB Please suggest?
--On Tuesday, August 28, 2012 5:29 PM +0530 Yajuvendra Singh
<yajuvendra.singh(a)gmail.com> wrote:
Dear Experts,
Today we tried with to run the load with the below schema. We added about
.6M entries in the DB.
Still our performance is severely poor. (10 TPS)
Can anybody review our slapd.conf file and point us where we are wrong,
is there any other config we have missed out.
You don't provide any useful or relevant information, so it is impossible
to help you.
What version of OpenLDAP are you using?
What type of disk?
What type of file system?
What is your *exact* slapadd command?
etc.
There is virtually no tuning involved with MDB, although I strongly
recommend you read Howard's notes about the writeback bits for EXT4 etc he
made in a recent post to -technical about MDB.
--Quanah
--
Quanah Gibson-Mount
Sr. Member of Technical Staff
Zimbra, Inc
A Division of VMware, Inc.
--------------------
Zimbra :: the leader in open source messaging and collaboration
4118
days inactive
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9 comments
5 participants
participants (5)
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aryan rawat -
Chris Card -
Howard Chu -
Quanah Gibson-Mount -
Yajuvendra Singh