Re: Performances issues with SSD volume ? - Mailing list pgsql-admin

From Thomas SIMON
Subject Re: Performances issues with SSD volume ?
Date
Msg-id 5559F558.6050307@neteven.com
Whole thread Raw
In response to Re: Performances issues with SSD volume ?  (Wei Shan <weishan.ang@gmail.com>)
List pgsql-admin
Hi Wei,
Yes i'm using RAID (megacli card), battery is ok, i had already checked BBU :)

Cheers
Thomas
Le 18/05/2015 15:52, Wei Shan a écrit :

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@neteven.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@neteven.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



pgsql-admin by date:

Previous
From: Thomas SIMON
Date:
Subject: Re: Performances issues with SSD volume ?
Next
From: Glyn Astill
Date:
Subject: Re: Performances issues with SSD volume ?