[pve-devel] multipath problems

Dietmar Maurer dietmar at proxmox.com
Wed Aug 22 08:31:03 CEST 2012

> what is your hardware config ?( cpu/ram/disk).

I just use some slow boxes to test. But I get around 150MB/s when I use a windows client,
so that can't be the problem.

> what's your raid level ? (raid-z, mirrors) do you use sas or sata disk?
> some quick performnce tuning,through gui:
> :2000/settings/preferences/?this_form=sys_form
> zfs_no_cacheflush=yes
> Sys_zfs_vdev_max_pending = 1 for sata, = 10 for sas

I do not want to tune - IMHO there must be some fundamental bug. 

> Also if you want to have more sequential bandwith, you can try to use big
> block size for zvol, like 128K. (I setup 4K by default in my module).

Yes, I guess I use the wrong benchmark. Thanks for that hint.

> seq read
> fio --filename=/dev/dm-20 --direct=1 --rw=read --bs=1m --size=20G --
> numjobs=200 --runtime=60 --group_reporting --name=file1

With that I get about 153MB/s:
# fio --filename=/dev/mapper/mpath1 --direct=1 --rw=read --bs=1m --size=20G --numjobs=200 --runtime=60 --group_reporting --name=file1
Run status group 0 (all jobs):
   READ: io=8978MB, aggrb=149921KB/s, minb=153519KB/s, maxb=153519KB/s, mint=61322msec, maxt=61322msec

So I guess that indicates that multipathing is working correctly.

Many thanks for your help!

- Dietmar

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