Hi Tomas,
We have a lot of small updates and some inserts. The database size is at 35GB including indexes and TOAST. We think it will keep growing to about 200GB. We usually have a burst of about 500k writes in about 5-10 minutes which basically cripples IO on the current servers. I've tried to increase the checkpoint_segments, checkpoint_timeout etc. as recommended in "PostgreSQL 9.0 Performance" book. However, it seems like our server just couldn't handle the current load.
Here is the server specs:
Dual E5620, 32GB RAM, 4x1TB SAS 15k in RAID10
Here are some core PostgreSQL configs:
shared_buffers = 2GB # min 128kB
work_mem = 64MB # min 64kB
maintenance_work_mem = 1GB # min 1MB
wal_buffers = 16MB
checkpoint_segments = 128
checkpoint_timeout = 30min
checkpoint_completion_target = 0.7
Thanks,
Cuong
On Fri, May 17, 2013 at 10:06 AM, Tomas Vondra <tv@xxxxxxxx> wrote:
Hi,
What does "heavy write" mean in your case? Does that mean a lot of small
On 16.5.2013 16:46, Cuong Hoang wrote:
> Hi all,
>
> Our application is heavy write and IO utilisation has been the problem
> for us for a while. We've decided to use RAID 10 of 4x500GB Samsung 840
transactions or few large ones?
What have you done to tune the server?
Streaming replication allows zero data loss if used in synchronous mode.
> Pro for the master server. I'm aware of write cache issue on SSDs in
> case of power loss. However, our hosting provider doesn't offer any
> other choices of SSD drives with supercapacitor. To minimise risk, we
> will also set up another RAID 10 SAS in streaming replication mode. For
> our application, a few seconds of data loss is acceptable.
It should be.
> My question is, would corrupted data files on the primary server affect
> the streaming standby? In other word, is this setup acceptable in terms
> of minimising deficiency of SSDs?
Have you considered using a UPS? That would make the SSDs about as
reliable as SATA/SAS drives - the UPS may fail, but so may a BBU unit on
the SAS controller.
Tomas
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