Re: Hardware/OS recommendations for large databases (

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(at)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(at)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: