On 05/20/2011 08:34 AM, Roman Mamedov wrote:
On Fri, 20 May 2011 08:18:32 -0400
Joe Landman<joe.landman@xxxxxxxxx> wrote:
Second off, you can turn any of the expensive RAID cards into an 'JBOD'
by doing something like this:
1) have the unit configured in RAID mode
2) build virtual disks out of single drives, as RAID0.
3) iterate 2 until you exhaust your drives.
4) make sure you prevent these drives from messing with your boot drive
order ... some bioses "helpfully" reorganize new drives for you by
messing with this list.
Once the drive is a 1 disk RAID0, you get the cache, and the BBU for the
cache. Yeah, its a little weird. But it does work (we've done this
with some LSI8888's).
But can you then access SMART of the individual drives?
I don't view the loss of direct SMART access as a bad thing ... most of
the RAID cards will give you CLI access to this data, if in a convoluted
manner. SMART's utility is generally pretty questionable (see the
Google paper for a discussion on the profound lack of correlation of
SMART parameters with actual failure rates). But its there if you want it.
Or will you see only some bogus block devices which do not accept SMART
commands, do not return real drive identity, and present themselves as RAID0
#1, RAID0 #2 etc. instead?
The RAID will provide you an abstraction (e.g. a layer you have to walk
through) to your disks. Seeing what composes the RAID is generally not
hard, though you might need to write a quick and dirty parser for this.
The block devices are not bogus. They are logical block devices.
--
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics, Inc.
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