New subject: Slow Mod operations on LDAP

18 Jan 2023

      Hi Quanah
The current mdb data file is GB on disk. We are using XFS, we tried with
ext2 and ext4, we saw the same behavior for slow mods.
2376455:/var/lib/ldap$ sudo du -sh data.mdb
11G data.mdb
2376455:/var/lib/ldap$ sudo du -s data.mdb
10519776 data.mdb
The dump from slapcat is 200 MB approx. Whenever we add it to a new
instance, it balloons up to 10 GB and then stays around the same size.
local-backups$ du -sh ldapdump202301180000.ldif
204M ldapdump202301180000.ldif
Can DB size be a reason for slow mods? And, how do we investigate the slow
mod further?
Regards
Bhanush
On Tue, Jan 17, 2023 at 10:53 PM Quanah Gibson-Mount quanah@fast-mail.org
wrote:
...
--On Monday, January 16, 2023 10:47 AM +0530 Bhanush Mehta
bhanush.mehta@flipkart.com wrote:
...
Hi Quanah,
We see the same issue with 2.4.58 (compiled from source).
I am able to debug that mod operations are fast on a fresh mdb, but after
a certain number of operations the mdb size is going from 300 MB to 10
GB.
Hello,
Are you sure that the database is actually 10GB in size? Keep in mind that
back-mdb uses a sparse file, so the filesystem will often show the
database
as being the "size" of the MDB maxsize value, regardless of what the
actual
DB size is.
You can use du -h "file.mdb" to see the actual filesize.
For example, in a test system, I have:
maxsize 1073741824
which is 1GB.
If we look at the output of ls:
total 2704
-rw------- 1 root root 1073741824 May 17  2022 data.mdb
but the actual size on disk is:
du -h data.mdb
2.7M    data.mdb
Regards,
Quanah
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Re: Slow Mod operations on LDAP