trying to "brute-force" my RAID 5...
I have written some posts about this before... My 6 disk RAID 5 broke down because of hardware failure. When I tried to get it up'n'running again I did a --create without any missing disk, which made it rebuild. I have also lost all information about how the old RAID was set up..
I got a friend of mine to make a list of all the 6^6 combinations of dev 1 2 3 4 5 missing, and set it up this way :
"mdadm --create -n 6 -l 5 dev1 2 3 4 5 missing ; fdisk -l /dev/md0 ; mdadm --stop /dev/md0" .
But a "cat logfile | grep Linux" of the output of this script tells me that on no of these combination does it find a valid "type 83" partition.
shouldn't this work ???
Sevrin
Quoted 4 lines · Sevrin Robstad
I got a friend of mine to make a list of all the 6^6 combinations of dev 1 2 3 4 5 missing,
shouldn't this work ???
Only if you get the layout and chunk size right.
And make sure that you know whether you were using partitions (eg. sda1) or whole drives (eg. sda - bad idea).
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Quoted 23 lines · Molle Bestefich
Quoted 5 lines
Quoted 3 lines · Sevrin Robstad
I got a friend of mine to make a list of all the 6^6 combinations of dev 1 2 3 4 5 missing,
Quoted 8 lines
Quoted 1 line
shouldn't this work ???
Only if you get the layout and chunk size right.
And make sure that you know whether you were using partitions (eg. sda1) or whole drives (eg. sda - bad idea).
Thanks for replying.. I guess I'm pretty sure that ONE of the 66 combination should be the right one?? And chunk size - 64kbyte is default, yes ? I created the RAID when I installed Fedora Core 3 some time ago, didn't do anything special so the chunks should be 64kbyte and parity should be left-symmetric ?
I'm also sure that I created it on partitions, and all disks has a
"Linux Raid" partition on it.But still, when I grep the log of my script I get no partition out of any combination...
Any Idea ?
Sevrin
Quoted 3 lines · Sevrin Robstad
I created the RAID when I installed Fedora Core 3 some time ago, didn't do anything special so the chunks should be 64kbyte and parity should be left-symmetric ?
I have no idea what's default on FC3, sorry.
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Any Idea ?
I missed that you were trying to fdisk -l /dev/md0..
As others have suggested, search for filesystems using fsck, or mount, or what not ;-).
Quoted 8 lines · On Monday July 17, [email protected] wrote:
I have written some posts about this before... My 6 disk RAID 5 broke down because of hardware failure. When I tried to get it up'n'running again I did a --create without any missing disk, which made it rebuild. I have also lost all information about how the old RAID was set up..
I got a friend of mine to make a list of all the 6^6 combinations of dev 1 2 3 4 5 missing, and set it up this way :
Quoted 6 lines
"mdadm --create -n 6 -l 5 dev1 2 3 4 5 missing ; fdisk -l
/dev/md0; mdadm --stop/dev/md0" .
But a "cat logfile | grep Linux" of the output of this script tells me that on no of these combination does it find a valid "type 83" partition.shouldn't this work ???
No.
What are you expecting fdisk to tell you? fdisk lists partitions and I suspect you didn't have any partitions on /dev/md0
More likely you want something like
fsck -n -f /dev/md0
and see which one produces the least noise.
NeilBrown
Quoted 6 lines
What are you expecting fdisk to tell you? fdisk lists partitions and I suspect you didn't have any partitions on
/dev/md0
More likely you want something like
fsck -n -f/dev/md0and see which one produces the least noise.
Maybe a simple file -s /dev/md0 could do the trick, and would only produce output different from the mere "data" when the good configuration is found...
Signature · 1 line
F.-E.B.
Quoted 11 lines · Francois Barre
Quoted 6 lines
What are you expecting fdisk to tell you? fdisk lists partitions and I suspect you didn't have any partitions on
/dev/md0
More likely you want something like
fsck -n -f/dev/md0and see which one produces the least noise.
Maybe a simple file -s
/dev/md0could do the trick, and would only produce output different from the mere "data" when the good configuration is found...
More likely to produce an output whenever the 1st disk in the array is in the right place as it will just look at the 1st couple of sectors for the superblock.
I'd go with the fsck idea as it will try to inspect the rest of the filesystem also.
Brad
Signature · 3 lines
"Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so." -- Douglas Adams
Quoted 5 lines
More likely to produce an output whenever the 1st disk in the array is in the right place as it will just look at the 1st couple of sectors for the superblock.
I'd go with the fsck idea as it will try to inspect the rest of the filesystem also.
Obviously that's true, but it's still a good way to be sure of the first disk, and the time cost of the file -s is neglectible...Personally, I would have done both.