Linux Software RAID5 Recovery - command to find parameters?

Discussions on using the professional data recovery program R-STUDIO for RAID re-construction, NAS recovery, and recovery of various disk and volume managers: Windows storage spaces, Apple volumes, and Linux Logical Volume Manager.
Kor

Linux Software RAID5 Recovery - command to find parameters?

Post by Kor » Mon Nov 30, 2009 1:37 am

Hi there!

I'm trying to recover a Linux Software RAID5 array across 4 drives.
The unit is actually an Intel SS4200-E, which runs the EMC Lifeline (modified Linux distro).
I've been able to get into the OS via SSH, but I must admit that I am more of a Windows guy ...

So .. in order to use R-Studio to reconstruct the RAID5 array as a virtual array,
I need:
1) Disk Order
2) Block Size
3) Block Order
4) Offset

I've ran the "mdadm --misc --D" command
and it shows:
# mdadm --misc --detail /dev/evms/md0vol1
/dev/evms/md0vol1:
Version : 00.90.03
Creation Time : Mon Nov 23 20:42:02 2009
Raid Level : raid5
Array Size : 351633407 (335.34 GiB 360.07 GB)
Used Dev Size : 117218176 (111.79 GiB 120.03 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent

Update Time : Mon Nov 30 00:26:05 2009
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0

Layout : left-asymmetric
Chunk Size : 32K

UUID : 123ea828:086246bb:1bf9851c:532994b0
Events : 0.4

Number Major Minor RaidDevice State
0 254 0 0 active sync /dev/evms/.nodes/sda1
1 254 1 1 active sync /dev/evms/.nodes/sdb1
2 254 2 2 active sync /dev/evms/.nodes/sdc1
3 254 3 3 active sync /dev/evms/.nodes/sdd1
Here are some assumptions that I have made .. could someone please advise if I'm doing this correctly?

I'm assuming that the "Chunk Size" is the "2) Block Size"??

the Block order as displayed above is "Left Asymetric",
does that mean that I shoudl use "Left Asynchronis" as 3) Block Order?

Super-Block is also set to persistent,
the Super-Block size, I found out, is 256Bytes + (2Bytes per Drive) = 256 + 8 = 264Bytes for my 4 drives RAID5
So .. the "4) Offset" should be 264??
Is this correct?

Are there any more linux commands out that can help me find the right parameters?

1) Drive Order i have a rough idea...
using the mdadm command, it said that

is there a Linux command that allows me to find out which drive (by drive size is fine) are they?

Any advice is Greatly appreciated!!

-Kor

Alt
Site Moderator
Posts: 2271
Joined: Tue Nov 11, 2008 2:13 pm
Contact:

Re: Linux Software RAID5 Recovery - command to find parameters?

Post by Alt » Mon Nov 30, 2009 6:21 am

Kor wrote:
Here are some assumptions that I have made .. could someone please advise if I'm doing this correctly?

I'm assuming that the "Chunk Size" is the "2) Block Size"??
Yes.
Kor wrote:the Block order as displayed above is "Left Asymetric",
does that mean that I shoudl use "Left Asynchronis" as 3) Block Order?
Most likely. But maybe other standard layouts should be tried.
Kor wrote:Super-Block is also set to persistent,
the Super-Block size, I found out, is 256Bytes + (2Bytes per Drive) = 256 + 8 = 264Bytes for my 4 drives RAID5
So .. the "4) Offset" should be 264??
Is this correct?
I think the offset is 0 in this case.

Post Reply