[ProgClub programming] Hard drive performance

John Elliot V | ProgClub jj5 at progclub.org
Tue Jun 11 13:54:48 AEST 2019

On 11/6/19 8:02 am, Jedd Rashbrooke wrote:
> On Tue, 11 Jun 2019 at 01:25, John Elliot V | ProgClub <jj5 at progclub.org
> <mailto:jj5 at progclub.org>> wrote:
>     All of a sudden I'm getting really poor performance from a bunch of my
>     hard disks. I'm not sure what the pre-problem performance was like,
>     except that it wasn't a problem  ... 
>  If only there were tools that record performance metrics over time.
>  As they say in the classics, if you can't measure it, it's not a problem.

I have numbers!

So a comparable system (i.e. three disks in ZFS RAID5) processed its
scrub operation with reads at about 26M/s.

This system was doing a ZFS scrub with reads of about 800K/s, which has
since fallen all the way back to 252K/s, which is terrible terrible

I don't know what the relevant factors are or what I can do about this
problem. If you all of a sudden have I/O problems with some of your
drives how do you diagnose that..? Seems to me like it must be a
hardware problem. I was thinking maybe throttling due to high
temperatures, but the reported temperatures didn't seem to be too high.

|_|O|_| ProgClub
|_|_|O| Because every programmer needs a good club!
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