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




-----------------------------------------------------------------------------------------

This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error, please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee, you should not disseminate, distribute or copy this email. Please notify the sender immediately by email if you have received this email by mistake and delete this email from your system. If you are not the intended recipient, you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.

 

Any views or opinions presented in this email are solely those of the author and do not necessarily represent those of the organization. Any information on shares, debentures or similar instruments, recommended product pricing, valuations and the like are for information purposes only. It is not meant to be an instruction or recommendation, as the case may be, to buy or to sell securities, products, services nor an offer to buy or sell securities, products or services unless specifically stated to be so on behalf of the Flipkart group. Employees of the Flipkart group of companies are expressly required not to make defamatory statements and not to infringe or authorise any infringement of copyright or any other legal right by email communications. Any such communication is contrary to organizational policy and outside the scope of the employment of the individual concerned. The organization will not accept any liability in respect of such communication, and the employee responsible will be personally liable for any damages or other liability arising.

 

Our organization accepts no liability for the content of this email, or for the consequences of any actions taken on the basis of the information provided, unless that information is subsequently confirmed in writing. If you are not the intended recipient, you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.

-----------------------------------------------------------------------------------------