Thanks, Ulrich.
That made me do a bit searching, there's a nice summary of some of the ext4 performance options here: http://blog.smartlogicsolutions.com/2009/06/04/mount-options-to-improve-ext4...
Definitely cool ideas (but more academic for us specifically) - I'd be a bit nervous to use those options in our XenServer (with local disks) VM environment, when looking to only gain some %s in ext4 performance.
Andrew Eross CTO Locatrix Communications Office: +61 7 3123 1469 Mobile: +55 37 9858 9815 eross@locatrix.com
On Fri, Feb 7, 2014 at 5:21 AM, Ulrich Windl < Ulrich.Windl@rz.uni-regensburg.de> wrote:
Hi!
Another suggestion: Dependingon your secondary storage you could experiment with mount option barrier=0: If you have a RAID controller with battery backed-up cache (that guarantees that any data confirmed "written" to the host will acually be written in the end) it makes no sense to force the controller to flush the cache before the host may continue. Especially if you have big shared SAN storage system...
For plain local disks you are putting data integrity at risc, especially for journaled filesystems in you skip barrieres. Still if you plan a repeatable initial database load, you could disable barriers temporarily. In case of a system crash, you probably have to re-load all your data...
Ulrich
Andrew Eross eross@locatrix.com schrieb am 06.02.2014 um 16:59 in
Nachricht CAL_tfFdS4suKqn7ZFSkFGQ1rE7qEhsyyGOs0RqV_Ow71J_Ri8Q@mail.gmail.com:
Hi guys,
Ulrich - thanks for the suggestions - btrfs in particular is certainly worth a shot.
Quanah - very cool to hear about the 12.04 kernel and ext2 suggestions. thanks!
I've just run some new tests on a similar machine with 12.04.4 LTS and a newly installed 3.11.0-15-generic x86_64 kernel.
Exact same testing method as before, 10K records, etc:
Running on an ext4 partition:
Base-line, no extra options: 5m14s With "writemap" enabled: 9m40s With "writemap+mapasync" enabled: 4m35s
Overall, about the same as 10.04 for me.
I created a new ext2 partition to give that a shot on the 12.04 box.
Base-line, no extra options: 1m31s With "writemap" enabled: 1m33s With "writemap+mapasync" enabled: 1m41s
Ahah! I'd say that's the killer answer.
Summary for future generations who may see this thread:
- Using ext2 for your db directory (on Ubuntu at least) is waay faster
than ext4 (~2-3x as fast according to my tests). This is the secret as
far
as I'm concerned since you can use this while still using the most conservative DB options that don't risk your data. 2) Using "dbnosync+checkpoint" with mdb is the absolute fastest method,
but
at the cost of risking data loss
Cheers, Andrew
On Thu, Feb 6, 2014 at 5:08 AM, Ulrich Windl < Ulrich.Windl@rz.uni-regensburg.de> wrote:
Andrew Eross eross@locatrix.com schrieb am 05.02.2014 um 16:30 in
Nachricht CAL_tfFf2qW5BcT=Xs4uFOSUO=wL0AN=9CyfS+D-XYPLitMZ_aw@mail.gmail.com:
Hi Quanah,
Ubuntu 10.04 LTS Linux 2.6.32-43-generic-pae #97-Ubuntu SMP Wed Sep 5 16:59:17 UTC 2012
i686
GNU/Linux The latest OpenLDAP 2.4.39 All of those tests done with the mdb backend, of course, and the
actual
file system is ext4
Did you try btrfs? I'd guess it could be faster for massive random
writes.
It's a fairly stock 10.04 system, no special config/kernel changes.
Cheers, Andrew
On Wed, Feb 5, 2014 at 1:26 PM, Quanah Gibson-Mount <
quanah@zimbra.com
wrote:
--On Tuesday, February 04, 2014 6:52 PM -0200 Andrew Eross < eross@locatrix.com> wrote:
Thanks, Dieter, Quanah.
I've been doing some experimenting with those mdb options.
I ran a few tests with inserting 10,000 records, wiping the DB in between, and changing just the one option at a time:
Base-line, no extra options: 4m8sWith "writemap" enabled: 8m55s
With "writemap+mapasync" enabled: 5m12s With "dbnosync+checkpoint 0kb/1min": 0m14s
I know you answered some of this before, but please update with:
What kernel? What OpenLDAP version? What Ubuntu release? What filesystem for the LDAP DB?
Thanks,
Quanah
--
Quanah Gibson-Mount Architect - Server Zimbra, Inc.
Zimbra :: the leader in open source messaging and collaboration