Re: RAID 1 - drive failed - very slow queries even after drive replaced

On 23 Mar 2011, at 9:33, Merrick wrote:

> Backups used to take 25 minutes, and now take 110 minutes, before
> replacing the drive it became clear the backup was not going to finish
> since in 120 minutes it had only finished 200mb of 2.8gb.

A few obvious questions:
1. Are you sure you replaced the correct drive?
2. Did the mirror finish resyncing before you did above measurements?

> Before replacing the drive:
> -----------------------------------
> We noticed all of the queries were slow, many taking over 100 seconds.
> After we replaced the drives we noticed the queries are running 40
> seconds or more and most are 8 seconds or more where the same query
> used to take only 1 second. We have replaced a drive in this RAID 1
> before and nothing like this happened. The schema was not touched for
> at least 1 week prior to this.
>
> Since replacing the drive I have:
> -------------------------------------------
> Restored from a backup a few hours before the queries became very
> slow.
> Reindex all tables
> Vacuum all tables
> Analyze all tables

Are you sure it was the drive that broke? Or maybe you have some collateral hardware damage to, for example, your raid controller, cables, disk controller or motherboard? Maybe the new drive has different requirements than the old one had (more power, for example)?

Alban Hertroys

--
If you can't see the forest for the trees,
cut the trees and you'll see there is no forest.

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