On Sat, Mar 28, 2009 at 7:22 PM, Bob Friesenhahn <
bfrie...@simple.dallas.tx.us> wrote:

> On Sat, 28 Mar 2009, Michael Shadle wrote:
>
>  Well this is for a home storage array for my dvds and such. If I have to
>> turn it off to swap a failed disk it's fine. It does not need to be highly
>> available and I do not need extreme performance like a database for example.
>> 45mb/sec would even be acceptable.
>>
>
> I can see that 14 disks costs a lot for a home storage array but to you the
> data on your home storage array may be just as important as data on some
> businesses enterprise storage array.  In fact, it may be even more critical
> since it seems unlikely that you will have an effective backup system in
> place like large businesses do.
>
> The main problem with raidz1 is that if a disk fails and you replace it,
> that if a second disk substantially fails during resilvering (which needs to
> successfully read all data on remaining disks) then your ZFS pool (or at
> least part of the files) may be toast.  The more data which must be read
> during resilvering, the higher the probability that there will be a failure.
>  If 12TB of data needs to be read to resilver a 1TB disk, then that is a lot
> of successful reading which needs to go on.
>
> In order to lessen risk, you can schedule a periodic zfs scrub via a cron
> job so that there is less probabily of encountering data which can not be
> read.  This will not save you from entirely failed disk drives though.
>
> As far as Tim's post that NOBODY recommends using better than RAID5, I
> hardly consider companies like IBM and NetApp to be "NOBODY".  Only Sun RAID
> hardware seems to lack RAID6, but Sun offers ZFS's raidz2 so it does not
> matter.
>
>
Oh, and NetApp supporting RAID5?  Have any other good jokes for us?

--Tim
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