Goswin von Brederlow wrote:
Redeeman <redeeman@xxxxxxxxxxx> writes:
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.
Cheers,
John.
And just when I hit send I thought of something else.
Instead of the initial sync when creating a raid the bitmap could just
mark all blocks as unused. Much faster raid creation.
That sounds a lot like what I mentioned, therefore it must be right. See
the thread on sync on a new array, my reply to Neil.
--
Bill Davidsen <davidsen@xxxxxxx>
Even purely technical things can appear to be magic, if the documentation is
obscure enough. For example, PulseAudio is configured by dancing naked around a
fire at midnight, shaking a rattle with one hand and a LISP manual with the
other, while reciting the GNU manifesto in hexadecimal. The documentation fails
to note that you must circle the fire counter-clockwise in the southern
hemisphere.
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
