Re: Very slow checkpoints

Thanks.

Kernel is: 3.5.0-36-generic #57~precise1-Ubuntu

Also - xlog is on ext4; db partition is zfs (on top of hardware RAID1+0).

Regards,
Steve

----------------------------------------
> From: ilya.kosmodemiansky@postgresql-consulting.com
> Date: Wed, 18 Mar 2015 13:13:36 +0100
> Subject: Re: [PERFORM] Very slow checkpoints
> To: steven.jones1201@outlook.com
> CC: pgsql-performance@postgresql.org
>
> On Wed, Mar 18, 2015 at 12:58 PM, Steven Jones
> <steven.jones1201@outlook.com> wrote:
>> Yes BBU is on the controller; 1024Mb. It is a HP P410i controller, with write caching turned on the controller; off
ondisk level. 
>
>
> vm.dirty_background_bytes=67108864 and vm.dirty_bytes=536870912 looks
> resonable for 512MB BBU, you can calculate them for 1024 or
> recalculate them for dirty_background_ratio
>
> By the way, which kernel do you use?
>
>> We don't at this stage have any graphs, but we will set it up over the next 24hrs at least.
>
> Do not forget to have iostat statistics on them, at least latency,
> %iowait and %util, such parameters are very helpful.
>
> And I am always suspicious about zfs under heavy writes. It is
> reliable and quite comfortable in terms of configuration, but for
> speed ext4 or xfs with disabled barrier looks more reasonable
>
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>
>
>
> --
> Ilya Kosmodemiansky,
>
> PostgreSQL-Consulting.com
> tel. +14084142500
> cell. +4915144336040
> ik@postgresql-consulting.com
>
>
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