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Re: partitioning os swap data log tempdb

From: "Shridhar Daithankar" <shridhar_daithankar(at)persistent(dot)co(dot)in>
To: "'pgsql-performance(at)postgresql(dot)org'" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: partitioning os swap data log tempdb
Date: 2003-02-24 10:32:17
Message-ID: 3E5A4209.14763.368CC8@localhost (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On 24 Feb 2003 at 10:52, Schaefer, Mario wrote:

> Hi,
> we want to migrate from MS SQL Server (windows2000)
> to PostgreSQL (Linux) :-))
> and we want to use the old MSSQL Hardware.
> Dual Pentium III 800
> 1 GB RAM
> 2 IDE 10 GB
> 2 RAID Controller (RAID 0,1 aviable) with 2 9GB SCSI HDD
> 1 RAID Controller (RAID 0,1,5 aviable) with 3 18GB SCSI HDD
> The configuration for MS-SQL was this:
> OS on the 2 IDE Harddisks with Software-RAID1
> SQL-Data on RAID-Controller with RAID-5 (3 x 18GB SCSI Harddisks)
> SQL-TempDB on RAID-Controller with RAID-1 (2 x 9GB SCSI Harddisk)
> SQL-TransactionLog on RAID-Controller with RAID-1 (2 x 9GB SCSI Harddisk)
> Can i make a similar configuration with PostgreSQL?
> Or what is the prefered fragmentation for
> operatingsystem, swap-partition, data, indexes, tempdb and transactionlog?

Hmm.. You can put your OS on IDE and databases on 3x18GB SCSI. Postgresql can 
not split data/indexes/tempdb etc. So they will be on one drive. You don't have 
much of a choice here.

> What is pg_xlog and how important is it?

It is transaction log. It is hit every now and then for insert/update/deletes. 
Symlinking it to a separate drive would be a great performance boost. Put it on 
the other SCSI disk. AFAIK, it is a single file. I suggest you put WAL and xlog 
on other 2x9GB SCSI drive. You need to shut down postgresql after schema 
creation and symlink the necessary files by hand. If postgresql ever recreates 
these files/directories by hand, it will drop the symlinks and recreate the 
files. In that case you need to redo the exercise of symlinkg.

> What ist the prefered filesystem (ext2, ext3 or raiserfs)?

reiserfs or XFS.
> We want to use about 20 databases with varios size from 5 MB to 500MB per
> database
> and more selects than inserts (insert/select ratio about 1/10) for fast
> webaccess.

shouldn't be a problem. Tune shared_buffers around 150-250MB. Beef up FSM 
entries, sort mem and vacuum regularly. 


Slous' Contention:	If you do a job too well, you'll get stuck with it.

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