David Greaves wrote:
Tomasz Chmielewski wrote:
Peter Rabbitson schrieb:
Tomasz Chmielewski wrote:
I have a RAID-10 setup of four 400 GB HDDs. As the data grows by several
GBs a day, I want to migrate it somehow to RAID-5 on separate disks in a
separate machine.
Which would be easy, if I didn't have to do it online, without stopping
any services.
Your /dev/md10 - what is directly on top of it? LVM? XFS? EXT3?
Good point. I don't want to copy the whole RAID-10.
I want to copy only one LVM-2 volume (which is like 90% of that RAID-10,
anyway).
So I want to synchronize /dev/LVM2/my-volume (ext3) with /dev/sdr (now
empty; bigger than /dev/LVM2/my-volume).
(sda2, sdb2, sdc2, sdd2) -> RAID-10 -> LVM-2 -> my volume -> ext3
I've not used iSCSI but I wonder about using nbd : network block device
Use nbd to export /dev/md5 from machine 2.
Import /dev/nbd0 on machine 1.
Add nbd0 to the VG on machine 1
pvmove the data from /dev/md10 to /dev/nbd0 (ie the md5 on machine2 via nbd)
remove /dev/md10 from the VG.
The VG should now exist only on /dev/nbd0 on machine 2
stop the services and lvm on machine 1
start the lvm and services on machine 2.
I'd suggest testing this first <grin>.
Posts to the kernel mailing list indicate that people, including me,
have had issues with this since 2.6.10-rc versions. I got no "me too"
responses, so I figured something have changed, although yesterday
someone reported a hard crash using nbd.
Test it well, but it's the ideal solution, combined with a bitmap, for
getting in sync.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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