[PVE-User] Strange ZFS Performance

Pongrácz István pongracz.istvan at gmail.com
Wed Aug 19 19:33:33 CEST 2015


Hi Lindsay,

Could you post me the following results by private email (outputs of these commands)?

 
zpool status -v
 
zpool get all
 
zfs list
 
zfs get all (needed 2 times for the system and data)
 
arcstat.py


Questions:

 
did you turn on dedup on your pools?
 
do you use any non-default zfs/zpool settings?
 
how is your cpu load on normal and stressed (problematic) situation?
 
is it true, the situation depends on uptime? For example usually the situation happens after 2 weeks?
 
Or can you see any pattern when the bad situation happens?


Hints without too much explanations:

 
you can monitor your pool activity by the following command: zpool iostat -v 1 (a screenshot would be nice)
 
do not turn on dedup. if you turned on -> recreate your pool from backup without dedup enabled
 
the default memory usage of zfs is 50% of the physical RAM. Due to the interaction between the linux memory management and spl, the total used memory could be the double of the ARC size. In other words: plan your memory allocation: MEMORY_OF_ALLVM + 2 * ARC size 
 
probably it is much better to turn off swap, as the swap is on zfs:
 
 
any problem on zfs will bring your computer down -> like performance
 
if your system start to use swap, your system is underplanned (as I can see, this is not the case)
 
 
 
try to find a pattern of your performance issue


Best regards,

István

----------------eredeti üzenet----------------- 
Feladó: "Lindsay Mathieson" 
 
Címzett: "Dietmar Maurer" dietmar at proxmox.com 
CC: "ProxMox Users" 
 
Dátum: Mon, 17 Aug 2015 16:03:34 +1000 
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>
>
>Think I'll try reinstalling with EXT4 for the boot drive.
>
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>On 17 August 2015 at 14:50, Lindsay Mathieson lindsay.mathieson at gmail.com 
>lindsay.mathieson at gmail.com wrote:
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>On 17 August 2015 at 14:43, Dietmar Maurer dietmar at proxmox.com dietmar at proxmox.com 
>wrote:
> what kernel and zfs version do you run exactly?
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>Free install, updated to latest from the pve-no-sub repos
>
>uname -r
>3.10.0-11-pve
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>cat /var/log/dmesg | grep -E 'SPL:|ZFS:'
>[ 17.384858] SPL: Loaded module v0.6.4-358_gaaf6ad2
>[ 17.449584] ZFS: Loaded module v0.6.4.1-1099_g7939064, ZFS pool version 5000, ZFS 
>filesystem version 5
>[ 18.007733] SPL: using hostid 0xa8c00802
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>--
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>Lindsay
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>--
>
>Lindsay
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>__________________________________________________
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>pve-user at pve.proxmox.com 
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