Re: Performances issues with SSD volume ?

From: Wei Shan <weishan(dot)ang(at)gmail(dot)com>
To: Thomas SIMON <tsimon(at)neteven(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: Performances issues with SSD volume ?
Date: 2015-05-18 13:52:42
Message-ID: CAFe9ZTo-nj-UL5k8ypJeTAnnh2mRiqkLXWma4inPfsy7A9vxEA@mail.gmail.com
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Hi Thomas,

This is just a wild guess. Are you using hardware RAID? Is the cache
battery still working?

Cheers
On 18 May 2015 9:36 pm, "Thomas SIMON" <tsimon(at)neteven(dot)com> wrote:

> Hi matheus,
> thanks for reply.
>
> Kernel is slightly different ; with a 3.10.23-xxxx-std-ipv6-64 kernel (OVH
> kernel) on HDD server, and 3.2.65-1+deb7u1 kernel on SSD server.
> I'm using debian wheezy on both servers.
>
> I didn't changed the 2 parameters you talk about.
>
> Thanks,
>
> Thomas
>
> Le 18/05/2015 15:13, Matheus de Oliveira a écrit :
>
>
> On Mon, May 18, 2015 at 10:05 AM, Thomas SIMON <tsimon(at)neteven(dot)com> wrote:
>
>> After the change, I had the following behavior, and I don't understand
>> why : everything seems to work fine (load is ~6/7, when it was previously
>> ~25/30 on the HDD server), so the SSD server is faster than the HDD one,
>> and my apps run faster too, but after some time (can be 5 minutes or 2
>> hours), the load average increases suddently (can reach 150 !) and does not
>> decrease, so postgres and my application are almost unusable. (even small
>> requests are in statement timeout)
>
>
> Before we go mad, what is the OS/kernel/distro that you are using? Did
> it change from the previous one?
>
> If Linux, have you disabled transparent_huge_pages and zone_reclaim_mode
> (two known problematic Linux features)?
>
> Best regards,
> --
> Matheus de Oliveira
> Analista de Banco de Dados
> Dextra Sistemas - MPS.Br nível F!
> www.dextra.com.br/postgres
>
>
>

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