[OpenIndiana-discuss] zfs and usb drives

[Jonathan Adams]

We had servers (Solaris 10) setup with external USB drives for ZFS ...
and we had problems.

having more than 8 USB devices attached to a Solaris box caused us
problems, and in some cases having a USB keyboard/mouse connected was
enough to cause the whole USB subsystem to keel over.

after trying to resolve lots of unrelated problems we resorted to just
buying servers with more internal space, pulling the USB drives to
pieces and inserting them into the new servers.

the problems have now disappeared.

I am talking about Solaris 10, not Illumos, and it was the dodgy USB
support that was causing us grief.

We still use USB drives, but only for transferring data between
servers when some st*pid user decides to drop 20+Gb onto the server
and the link goes down, but it is no longer a primary storage medium.

Jon

On 31 May 2012 10:30, Jim Klimov <jimklimov at cos.ru> wrote:
> 2012-05-31 6:14, Bob Friesenhahn wrote:
>>
>> On Tue, 29 May 2012, Jay Heyl wrote:
>>>
>>>
>>> One idea is to use the external USB drives I've collected to create a
>>> separate pool for the non-critical data. I have four 2TB USB drives that
>>> have been performing flawlessly connected to Windows systems for quite a
>>> while. Any opinions on using them to set up another raidz pool? Is this a
>>> reasonable idea or a really bad idea?
>>
>>
>> I have been using USB drives in a mirror configuration for quite a few
>> years with zfs. No problems have been encountered due to using zfs. The
>> main thing I learned is to always export the pool before unplugging the
>> USB cables because the pool won't come back up if the cables are plugged
>> into different ports than before.
>>
>> Zfs scrub and resilver are obviously slower with USB drives.
>>
>> I have heard that one should always plug the drives directly into the
>> computer rather than into a USB bridge device.
>
>
> Also, somebody recently had an issue moving the drives between
> an USB enclosure and direct connection to the controller in the
> computer - reported sector sizes varied, and the pool couldn't
> be imported. If the drives are going to be in their enclosures
> forever (as i.e. WD warranty policy requires), this is not a
> problem - except that the box might report different "native"
> sector sizes than those really supported by disk hardware, and
> you might need to try enforcing one or another ashift (9, 12).
>
> HTH,
> //Jim Klimov
>
>
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