From: Luke Lonergan <llonergan@greenplum.com>
To: stange@rentec.com
Cc: Greg Stark <gsstark@mit.edu>
Cc: Dave Cramer <pg@fastcrypt.com>
Cc: Joshua Marsh <icub3d@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Hardware/OS recommendations for large databases (
Date: Mon, 21 Nov 2005 15:44:35 -0800
Message-ID: <BFA79BE3.14369%llonergan@greenplum.com> (raw)
In-Reply-To: <438241E5.2010701@rentec.com>
Alan,
Unless noted otherwise all results posted are for block device readahead set
to 16M using "blockdev --setra=16384 <block_device>". All are using the
2.6.9-11 Centos 4.1 kernel.
For those who don't have lmdd, here is a comparison of two results on an
ext2 filesystem:
============================================================================
[root@modena1 dbfast1]# time bash -c "(dd if=/dev/zero of=/dbfast1/bigfile
bs=8k count=800000 && sync)"
800000+0 records in
800000+0 records out
real 0m33.057s
user 0m0.116s
sys 0m13.577s
[root@modena1 dbfast1]# time lmdd if=/dev/zero of=/dbfast1/bigfile bs=8k
count=800000 sync=1
6553.6000 MB in 31.2957 secs, 209.4092 MB/sec
real 0m33.032s
user 0m0.087s
sys 0m13.129s
============================================================================
So lmdd with sync=1 is apparently equivalent to a sync after a dd.
I use 2x memory with dd for the *READ* performance testing, but let's make
sure things are synced on both sides for this set of comparisons.
First, let's test ext2 versus "ext3, data=ordered", versus reiserfs versus
xfs:
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To: pgsql-performance@postgresql.org
Cc: llonergan@greenplum.com, stange@rentec.com, gsstark@mit.edu, pg@fastcrypt.com, icub3d@gmail.com
Subject: Re: Hardware/OS recommendations for large databases (
In-Reply-To: <BFA79BE3.14369%llonergan@greenplum.com>
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