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Subject: Re: ZFS regimen: scrub, scrub, scrub and scrub again.
From: Artem Belevich <art@freebsd.org>
To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
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On Wed, Jan 23, 2013 at 12:22 PM, Wojciech Puchar
<wojtek@wojtek.tensor.gdynia.pl> wrote:
>>> While RAID-Z is already a king of bad performance,
>>
>>
>> I don't believe RAID-Z is any worse than RAID5.  Do you have any actual
>> measurements to back up your claim?
>
>
> it is clearly described even in ZFS papers. Both on reads and writes it
> gives single drive random I/O performance.

For reads - true. For writes it's probably behaves better than RAID5
as it does not have to go through read-modify-write for partial block
updates. Search for RAID-5 write hole.
If you need higher performance, build your pool out of multiple RAID-Z vdevs.