Re: Raid 5 --grow to fewer, larger drivers

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That is an interesting work around T, though it does have its own issues, namely the need to take the data off-line for the time of the copy over the network besides the hassle.

I would be interested to know why there would be any greater difficulty/risk in growing to fewer, larger disks than simply growing to more disks of the same size. The problem is that if you have a number of disks and need more space, you add another disk of the same size and lots of disks will eventually bite you on the bum, so being able to consolidate in the way I set out would be a real bonus and nice and straight forward (or maybe not!?)

Regarding the risk factor during any array resync, I should hope we all have a precious data backed up anyway!

Thanks for you £0.02 though :-)

Alex

Twigathy wrote:
In that situation, I think I'd be happier to hook all the disks up (If
not on the same machine, on two machines on the same [gigE] network,
make a new raid5 on the new set of disks, rsync stuff to the new array
and then retire the old array (Swapping in the array you just
created)... messing around resizing disks for this job just sounds
like mess and risk to me!

Just my £0.02 ;-)

T

2008/11/24 Alex Lilley <alex@xxxxxxxxxxxx>:
Senario:  raid5 with  4 x 120gb.

aim:  raid5 with 3 x 250gb

3 x 120gb disks replaced with 3 x 250gb, array has been rebuilt/resync'd at
original size. Can we remove the remaining 120gb drive and reshape the array
over the remaining 3 drives using all the new space.

I guessed --grow --raid-devices=3 --size-max would work but returns "can
change at most one of size, raiddisks, bitmap and layout"

I then --failed and --remove the remaining 120gb drive and tried --grow
--raid-devices=3 but receive "Cannot reduce number of data disks (yet)".

I am therefore slightly stumped!

Is this something that is actually possible or something that is planned for
because as the size of disk drives multiplies and the desire to keep tabs of
power usage increases it is likely that we will want to reduce the number of
disk, besides the obvious increased risk of failure introduced by having a
greater number of drives.

Regards

Alex
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