[PVE-User] Proxmox + ZFS: Performance issues

[Ralf]

Hi Yannis,

On 04/26/2016 12:30 AM, Yannis Milios wrote:
> Hi Ralf,
>
> Are both hard drives exactly the same model?
Yes, they are.
>
> I've noticed that your drive uses 512byte sector size (instead of 4K
> sector size which is the current trend).
Yes, 512/512.
>
> In that case, is your pool properly aligned to ashift=9 ?
zpool get ashift states, that ashift=12. In that case, should it be
changed to 9 or is it even possible to change this parameter?

  Ralf
>
> More info here:
> http://wiki.illumos.org/display/illumos/ZFS+and+Advanced+Format+disks
>
> Regards,
>
> Yannis
>
> On 04/25/2016 09:38 PM, Ralf wrote:
>> On 04/25/2016 10:14 PM, Lindsay Mathieson wrote:
>>> On 25/04/2016 11:43 PM, Ralf wrote:
>>>> some more random analysis:
>>>> I used atop to debug the problem.
>>>>
>>>> Turned out, that disks are 100% busy and the average io time is beyond
>>>> all hope. ZFS seems to read/write/arrange things in a random and
>>>> not in
>>>> a sequential way.
>>>
>>> What does "iotop -P --only" show?
>> That dd is using 100% of io. Ram usage is 5/10 GiB at the moment, so
>> more than enough free ram.
>>> I suspect lack of ram is your problem.
>> Why do I need so much RAM for mirror raid? All ram-intensive features
>> are turned off.
>>
>>    Ralf
>>
>>
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