On Wed, Feb 06, 2002 at 04:46:01PM +0100, Martin Bene wrote:
> Hi Jakob,
>
> > Also, every now and then someone says they will try it out,
> > but I have yet to
> > get a failure report (and I kind of miss success reports as
> > well - hint ! ;)
>
> I just started playing with the raidreconf tool, I've tried to use it for
> adding a 3rd disk to a two-disk raid0 stripeset.
Great, thanks for the feedback !
>
> result: if the raidtab is correct, expansion works great.
Cool
>
> caveat: I've also managed to use it to completely trash the contents of a stripeset: if the sequence of drives in raidtab doesn't match the actual setup, raidreconf doesn't detect this and happily scrambles your data.
Um... But, it scrambles those data pretty darn good, wouldn't you say ? ;)
That's obviously going to be a problem. Thanks for testing.
>
> example:
> raidtab used to create the original array:
> ==========================================
> raiddev /dev/md3
> raid-level 0
> nr-raid-disks 2
> chunk-size 32
> persistent-superblock 1
> device /dev/hdb5
> raid-disk 0
> device /dev/hda5
> raid-disk 1
>
> raidtab used when expanding the array:
> ======================================
> raiddev /dev/md3
> raid-level 0
> nr-raid-disks 2
> chunk-size 32
> persistent-superblock 1
> device /dev/hda5
> raid-disk 0
> device /dev/hdb5
> raid-disk 1
>
> Result: scrambled data.
>
> While noone would consciously do something like that, it's a situation fairly easy to get into if disks were moved around. Examples: different controller, moving disks between ide cables.
Of course.
>
> So: be very sure that the sequence of disks in your raidtab matches your running array before atempting to use raidreconf.
I should fix it.
>
> Bye, Martin
> PS: just for the record: I didn't loose any data, I set this case up just to see if raidreconf would catch it :-)
I really appreciate the feedback !
How was the speed, by the way - I am aware that raidreconf is not a
speed-devil, but I'd like some information about how various systems perform.
Now, you used two disks on the same IDE channel, so I suppose things didn't
exactly fly.
--
................................................................
: jakob@unthought.net : And I see the elder races, :
:.........................: putrid forms of man :
: Jakob Østergaard : See him rise and claim the earth, :
: OZ9ABN : his downfall is at hand. :
:.........................:............{Konkhra}...............:
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