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Date:      Wed, 02 May 2012 18:06:04 -0400
From:      "Simon" <simon@optinet.com>
To:        "Rich" <rercola@pha.jhu.edu>
Cc:        "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org>
Subject:   Re: Replacing dead drives in ZRAID2
Message-ID:  <20120502220609.D7A60106579A@hub.freebsd.org>
In-Reply-To: <CAOeNLuoUQNv16Td8wcJzK2x==M0esYh6Y2aGvuN3sOE_W7LoSg@mail.gmail.com>

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I'm trying to figure out why it's not working with ahd driver. It's beginning to look
more and more as if I shouldn't use ZFS with ahd driver. That's why I asked for
someone to confirm whether or not the two can be used together. It also seems
that everyone moved on to SAS/SATA technology, albeit it's hard to believe.
There are few machine I have from early 2007, so 5 years old, that have the
same controller onboard. So while u320 is a decade old technology, many
servers been built using it in 2006+

Unless someone can confirm otherwise, I will assume ahd and ZFS do not
work well together when it comes to dying/swapping drives.

Having said the above, is there any FreeBSD RAID software I can use with
ahb driver that won't give me same issues I'm experiencing with ahd and ZFS?
vinum? gmirror? Can I expect them to work better with ahd given ahd cannot
handle pulling of working drives out of SAF-TE aware enclosure?

Thank you,
Simon

On Wed, 2 May 2012 17:18:22 -0400, Rich wrote:

>It's perfectly possible to do a 3-way RAID-Z2 - just not useful, AFAIK.

>Also, Simon, I think the disconnect between you and the mailing list
>is that you are observing bad behavior of the system when you remove
>the drives, and you think this is a ZFS problem. This is not a ZFS
>problem - if the underlying storage driver (ahd) freezes up and stops
>handling requests (which is what it sounds like you're describing
>here), there's not much ZFS can do about it.

>- Rich

>On Wed, May 2, 2012 at 5:05 PM, Mark Felder <feld@feld.me> wrote:
>> First of all, you're testing on decade old SCSI hardware that probably
>> hasn't seen any serious use on a newer FreeBSD install in a very, very long
>> time.
>>
>> Secondly, I'm confused about the concept of a "3 drive RAIDZ2". How is that
>> even possible? Two drives have to be parity, so the last drive is... the
>> entire dataset? Why aren't you just doing a 3-way mirror?
>>
>> And finally yes, you can just yank drives in a ZFS array to simulate a
>> failure. After reinsertion you have to manually add them back to the pool,
>> but it certainly works.
>>
>> _______________________________________________
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