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Cc: Ivan Voras <ivoras@freebsd.org>, freebsd-questions@freebsd.org
Subject: Re: FreeBSD + ZFS on a production server?
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>>> random write speeds (but still at least half of single drive). but
>>> this is advertised as a feature
>>
>> Is this because of checksum verification (the need to read all
>> components) or something else? Any documentation/references?
>
> RAID-Z stores a single checksum over the whole stripe, instead of
> checksumming each disks's section separately, so it has to read from
> all disks to validate the stripe.  Only random reads are penalized,
> though.

random reads are most common read on unix, unless you process linearly 
huge files, but that's fast on UFS too.