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

[Bartosz Stec]

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.

-- 
Bartosz Stec