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Date: Tue, 16 Jul 2013 14:55:04 -0700
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Subject: Re: ZFS memory exhaustion?
From: javocado <javocado@gmail.com>
To: Freddie Cash <fjwcash@gmail.com>
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Thank you. Is gstat the best way to watch zfs i/o ?


On Tue, Jul 16, 2013 at 1:50 PM, Freddie Cash <fjwcash@gmail.com> wrote:

> On Tue, Jul 16, 2013 at 1:26 PM, javocado <javocado@gmail.com> wrote:
>
>> I have a couple questions:
>>
>> - what does it look like when zfs needs more physical memory / is running
>> out of memory for its operations?
>>
>
> Disk I/O drops to 0, reading/writing any file from the pool appears to
> "hang" the console, programs already loaded into RAM continue to work so
> long as they don't touch the pool, etc.
>
>
>>
>> - what diagnostic numbers (vmstat, etc.) should I watch for that?
>>
>> Top output will show Wired at/near 100% of RAM.
>
>
>> swapinfo shows zero (basically zero) swap usage, so it doesn't look like
>> things get that bad.
>>
>>
> ZFS uses non-swappable kernel memory, so you won't ever see swap used when
> ZFS runs out of RAM.
>
> Those are the symptoms we've noticed when our ZFS systems have run out of
> RAM.
>
>
> --
> Freddie Cash
> fjwcash@gmail.com
>