Redeeman wrote:
On Sat, 2009-05-30 at 14:35 +0100, John Robinson wrote:
On 30/05/2009 06:44, SandeepKsinha wrote:
Hi all,
Say If I have a RAID 5 array of 50GB of five disks of 10GB each.
I have data of 5GB. When a disk fails and replaced with a spare disk.
Will the reconstruction happen only for the 5GB allocated disk blocks
or it will happen for the whole disk size.
The whole disc size, for now anyway; md does not currently note which
blocks have been used by its client (the filesystem, LVM, whatever).
Is it possible to make reconstruction intelligent enough to keep it optimized ?
This has been discussed in combination with supporting SSD drives' TRIM
function, and would mean md had to keep track of used chunks or possibly
even sectors using a bitmap or something like that, but whether anyone's
working on it I don't know.
I would say it should be possible to 'query' the filesystem for that
information. Obviously this will only work if you run a filesystem on it
which supports it, but it would seem like a nicer solution than a bitmap
for it.
There is a program which does that, but i think it was for ext2. Read
the inodes and saved the data. I believe 'dump' does something similar,
but it's on a file system basis and I don't recall (or care much about)
the details.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
"You are disgraced professional losers. And by the way, give us our money back."
- Representative Earl Pomeroy, Democrat of North Dakota
on the A.I.G. executives who were paid bonuses after a federal bailout.
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