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 <t...@fuzzy.cz> wrote: > Hi, > > 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 > > What does "heavy write" mean in your case? Does that mean a lot of small > transactions or few large ones? > > What have you done to tune the server? > > > 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. > > Streaming replication allows zero data loss if used in synchronous mode. > > > 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? > > It should be. > > 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 > > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
