Re: ZFS on Linux in production?

[Nicolas Thierry-Mieg <Nicolas.Thierry-Mieg@xxxxxxx>]

On 11/04/2013 08:01 PM, John R Pierce wrote:
> On 11/4/2013 10:43 AM, Les Mikesell wrote:
>> On Mon, Nov 4, 2013 at 12:15 PM, Markus Falb
>>> <wnefal@xxxxxxxxx>  wrote:
>>>>>>
>>> 3) NEVER let a zpool fill up above about 70% full, or the performance
>>>>> really goes downhill.
>>>
>>>> Why is it? It sounds cost intensive, if not ridiculous.
>>>> Disk space not to used, forbidden land...
>>>> Is the remaining 30% used by some ZFS internals?
>> Probably just simple physics.  If ZFS is smart enough to allocate
>> space 'near' other parts of the related files/directories/inodes it
>> will have to do worse when there aren't any good choices and it has to
>> fragment things into the only remaining spaces and make the disk heads
>> seek all over the place.   Might not be a big problem on SSD's though.
>
> even on 0 seek time SSDs, fragmenting files means more extents to track
> and process in order to read that file.

but why would this be much worse with ZFS than eg ext4?

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