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From: Milen Kulev <makulev@gmx.net>
To: 'Denis Lussier' <denisl@enterprisedb.com>
To: 'Luke Lonergan' <llonergan@greenplum.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: XFS filessystem for Datawarehousing -2
Date: Thu, 3 Aug 2006 21:56:19 +0200
Message-ID: <024801c6b736$e3505ed0$0a00a8c0@trivadis.com> (raw)
In-Reply-To: <5f820f750608022236yd8dd6escce3bb849b91bddb@mail.gmail.com>

Hi Dennis, 
I am just cusrios to try PG with different block sizes ;)  I don't know how much performance the bigger block size will
bring (I mean 32k or 64k , for example, for DWH applikations).
I am surprised to hear that OCFS2.0 (or any her FS usind direct I/O) performs well  with PG. A month ago I have
performed a simple test with Veritas FS, with and than without cache (e.g. direct I/O).  I have started  1  , then 2, ,
then 3, then 4 parallel INSERT processes. 
Veritas FS WITH FS cache outperformed the direct I/O version by factor 2-2.5 !
I haven't tested woth OCFS2.0 though. I am not sure that OCFS2.0 is  the good choice  for  PG data and index
filesystems.
For WAL -> perhaps.
 
Best Regards. Milen 

-----Original Message-----
From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of Denis Lussier
Sent: Thursday, August 03, 2006 7:36 AM
To: Luke Lonergan
Cc: Milen Kulev; pgsql-performance@postgresql.org
Subject: Re: [PERFORM] XFS filessystem for Datawarehousing -2



I was kinda thinking that making the Block Size configurable at InitDB time would be a nice & simple enhancement for PG
8.3.  My own personal rule of thumb for sizing is 8k for OLTP, 16k for mixed use, & 32k for DWH. 

I have no personal experience with XFS, but, I've seen numerous internal edb-postgres test results that show that of all
file systems... OCFS 2.0 seems to be quite good for PG update intensive apps (especially on 64 bit machines). 


On 8/1/06, Luke Lonergan <llonergan@greenplum.com> wrote: 

Milen,

On 8/1/06 3:19 PM, "Milen Kulev" <makulev@gmx.net> wrote:

> Sorry, forgot to ask:
> What is the recommended/best  PG block size for DWH  database?  16k, 32k, 64k 
> ?
> What hsould be the relation  between XFS/RAID stripe size and PG block size ?

We have found that the page size in PG starts to matter only at very high
disk performance levels around 1000MB/s.  Other posters have talked about 
maintenance tasks improving in performance, but I haven't seen it.

- Luke



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