Re: transferring RAID-1 drives via sneakernet
Jeff Breidenbach wrote: I'm planning to take some RAID-1 drives out of an old machine and plop them into a new machine. Hoping that mdadm assemble will magically work. There's no reason it shouldn't work. Right? old [ mdadm v1.9.0 / kernel 2.6.17 / Debian Etch / x86-64 ] new [ mdad v2.6.2 / kernel 2.6.22 / Ubuntu 7.10 server ] I've done it several times. Does the new machine have a RAID array already? David - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: transferring RAID-1 drives via sneakernet
It's not a RAID issue, but make sure you don't have any duplicate volume names. According to Murphy's Law, if there are two / volumes, the wrong one will be chosen upon your next reboot. Thanks for the tip. Since I'm not using volumes or LVM at all, I should be safe from this particular problem. - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: transferring RAID-1 drives via sneakernet
Jeff Breidenbach wrote: Does the new machine have a RAID array already? Yes.. the new machine already has on RAID array. After sneakernet it should have two RAID arrays. Is there a gotcha? It's not a RAID issue, but make sure you don't have any duplicate volume names. According to Murphy's Law, if there are two / volumes, the wrong one will be chosen upon your next reboot. -- Brendan Conoboy / Red Hat, Inc. / [EMAIL PROTECTED] - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: transferring RAID-1 drives via sneakernet
Does the new machine have a RAID array already? Yes.. the new machine already has on RAID array. After sneakernet it should have two RAID arrays. Is there a gotcha? - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Got raid10 assembled wrong - how to fix?
I just discovered (the hard way, sigh, but not too much data loss) that a 4-drive RAID 10 array had the mirroring set up incorrectly. Given 4 drvies A, B, C and D, I had intended to mirror A-C and B-D, so that I could split the mirror and run on either (A,B) or (C,D). However, it turns out that the mirror pairs are A-B and C-D. So pulling both A and B off-line results in a non-functional array. So basically what I need to do is to decommission B and C, and rebuild the array with them swapped: A, C, B, D. Can someone tell me if the following incantation is correct? mdadm /dev/mdX -f /dev/B -r /dev/B mdadm /dev/mdX -f /dev/C -r /dev/C mdadm --zero-superblock /dev/B mdadm --zero-superblock /dev/C mdadm /dev/mdX -a /dev/C mdadm /dev/mdX -a /dev/B I'm assuming that fresh spares will be assigned to the lowest available slot. I just get nervous about commands with names like --zero-superblock when I have data I'd rather not lose. Thanks! - To unsubscribe from this list: send the line unsubscribe linux-raid in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
patch for raid10,f1 to operate like raid0
This patch changes the disk to be read for layout far 1 to always be
the disk with the lowest block address.
Thus the chunks to be read will always be (for a fully functioning array)
from the first band of stripes, and the raid will then work as a raid0
consisting of the first band of stripes.
Some advantages:
The fastest part which is the outer sectors of the disks involved will be used.
The outer blocks of a disk may be as much as 100 % faster than the inner blocks.
Average seek time will be smaller, as seeks will always be confined to the
first part of the disks.
Mixed disks with different performance characteristics will work better,
as they will work as raid0, the sequential read rate will be number of
disks involved times the IO rate of the slowest disk.
If a disk is malfunctioning, the first disk which is working, and has the lowest
block address for the logical block will be used.
Signed-off-by: Keld Simonsen [EMAIL PROTECTED]
--- raid10.c2008-02-12 00:50:59.0 +0100
+++ raid10-ks.c 2008-02-12 00:51:09.0 +0100
@@ -537,7 +537,7 @@
current_distance = abs(r10_bio-devs[slot].addr -
conf-mirrors[disk].head_position);
- /* Find the disk whose head is closest */
+ /* Find the disk whose head is closest,
+ or for far 1 the closest to partition beginning */
for (nslot = slot; nslot conf-copies; nslot++) {
int ndisk = r10_bio-devs[nslot].devnum;
@@ -557,7 +557,11 @@
slot = nslot;
break;
}
- new_distance = abs(r10_bio-devs[nslot].addr -
+
+/* for far 1 always use the lowest address */
+ if (conf-far_copies 1)
+ new_distance = r10_bio-devs[nslot].addr;
+ else new_distance = abs(r10_bio-devs[nslot].addr -
conf-mirrors[ndisk].head_position);
if (new_distance current_distance) {
current_distance = new_distance;
-
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