ZFS tuning [was: hardware for home use large storage]

[jhell]

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On Wed, 17 Feb 2010 04:53, jhell@ wrote:
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> gpg: Signature made Wed Feb 17 04:53:27 2010 EST using RSA key ID 89D8547E
> gpg: Good signature from "jhell <jhell at DataIX.net>"
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>
> On Wed, 17 Feb 2010 03:56, bartosz.stec@ wrote:
>> On 2010-02-17 09:32, Torfinn Ingolfsen wrote:
>>> On Wed, 17 Feb 2010 09:19:49 +0100
>>> Bartosz Stec<bartosz.stec at it4pro.pl>  wrote:
>>> 
>>> 
>>>> So here's my reply (last line seems most interesting ;) :
>>>> 
>>> [...snipped...]
>>> 
>>>> Illegal division by zero at ./arc_summary.pl line 242.
>>>> 
>>> FWIW, I also got this line when I ran this script on my idle zfs server.
>>> 
>> I'm not a PERL programmer (or programmer at all ;), but what I see is 
>> script
>> doesn't check if L2ARC is used at all, so it will always try compute these
>> lines:
>> 
>> printf("\tL2 Hit Ratio:\t\t\t%0.2f%%\t%d\n", 100 * ( $l2_hits / ( $l2_hits 
>> +
>> $l2_misses )), $l2_hits );
>> printf("\tL2 Miss Ratio:\t\t\t%0.2f%%\t%d\n", 100 * ( $l2_misses / ( 
>> $l2_hits
>> + $l2_misses )), $l2_misses );
>> printf("\tL2 Feeds Ratio:\t\t\t%0.2f%%\t%d\n", 100 * ( $l2_feeds / ( 
>> $l2_hits
>> + $l2_misses )), $l2_feeds );
>> 
>> Without active L2ARC it will always generate divide at zeo error, so it 
>> seems
>> that additional check for usable L2ARC values is needed at first place.
>> 
>> 
>
> Thanks for reporting this. As I am usually on a system that is using a
> L2ARC I wouldn't have noticed it.
>
> I should have this fixed in about 10 hours. But as I am writing this email
> I am heading off to bed, work calls in the morning.
>
> Check back tomorrow night for a updated version and adjust the current to
> your liking for the moment.
>
> ;) Thanks again.
>
> --
>
> jhell
>
>
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>

I take that back.

I just uploaded a modified version that I wrapped with a if statement to 
check and see if l2_hits >= 0.

If you don't have a L2ARC you will now get a message explaining why its not 
included in your summary.

I couldn't sleep until I fixed this knowing that more people are probably 
going to come across this problem and email back.

New rev: 184

MD5 (arc_summary.pl) = f47bac165e7bf707d5f81cfdd007c30a
SHA256 (arc_summary.pl) = 794dce069ff649598d99204b362d141a19da47dcf60ec165b260d55a5c9d493f
SIZE (arc_summary.pl) = 12695

http://jhell.googlecode.com/files/arc_summary.pl
http://jhell.googlecode.com/files/arc_summary.pl.asc

Now I can finally sleep ;)

- -- 

  jhell

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