Re: ATTN: Clodaldo was Performance problem. Could it be related to 8.3-beta4?

Tom Lane wrote:
> I went through this thread again, and noticed something that no one
> seems to have remarked on at the time: the vmstat numbers near the
> bottom of this post
>
> http://archives.postgresql.org/pgsql-general/2008-01/msg00161.php
>
> show close to 100% I/O wait time (either that or 50% idle 50% I/O wait,
> which I suspect is an artifact).  We subsequently concluded that the
> "SELECT" side of the INSERT/SELECT command is not where the problem is,
> so all the cycles are going into the actual row insertion part.
>
> I don't know of any reason to think that insertion is slower in 8.3
> than it was in 8.2, and no one else has reported anything of the sort.
> So I'm leaning to the idea that this suggests some kind of
> misconfiguration of the disk setup in Clodoaldo's new server.  There
> was some earlier discussion about not having the RAID configured right:
>
> http://archives.postgresql.org/pgsql-general/2008-01/msg00169.php
>
> I'm thinking it's still not right :-( but have no real expertise
> at diagnosing such problems.  Anyone?

Per the thread.

# cat /proc/mdstat
Personalities : [raid1] [raid6] [raid5] [raid4] [raid0]
md2 : active raid1 sda1[0] sdb1[1]
       224768 blocks [2/2] [UU]

md0 : active raid0 sda2[0] sdb2[1]
       4497920 blocks 256k chunks

md1 : active raid1 sda3[0] sdb3[1]
       310094592 blocks [2/2] [UU]


I don't see anything immediately wrong here. md0 is raid 0 and probably
his swap. md2 is probably boot and md1 is probably / . All volumes show
online.

If we are sure that this issue is apparent actual row insertion it
should be easy to duplicate. I will do some testing on my box which is
similar. I have 2gig of ram, dual core and a raid 1 with SATA drives.

Sincerely,

Joshua D. Drake




>
>             regards, tom lane
>
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