How Do I find the Offset in a NAS RAID 5

[toooldforthiscrap]

I am trying to recover a Seagate BlackArmour 4TB RAID5 NAS. How do I find the offset?
I know the disk order, that its left synchronous and a 128K stripe, but how do I find the offset?

[DR-Kiev]

Two ways.
Offset is mentioned in LVM config ,or, if you know how partition starts, you can easy recognized it in HEX

[toooldforthiscrap]

Two ways.
Offset is mentioned in LVM config ,or, if you know how partition starts, you can easy recognized it in HEX

What if you don't know either? This is a Seagate Blackarmor which is built with Linux.

[einstein9]

Two ways.
Offset is mentioned in LVM config ,or, if you know how partition starts, you can easy recognized it in HEX

What if you don't know either? This is a Seagate Blackarmor which is built with Linux.

i guess, in this case have to pay him for assistance if you want.

good luck

[toooldforthiscrap]

i guess, in this case have to pay him for assistance if you want.

good luck

Indeed, forums 'aint what they used to be

[ROb]

PM Sent ...

[lcoughey]

I honestly haven't seen too many linux software RAIDs with an offset. Though, most have multiple RAIDed partitions:

P1 - small os config (mirrored on all drives)
P2 - swap (mirrored on all drives)
P3 - main LVM (RAID 0,1 or 5, depending the RAID setup)

My usual way to reconstruct linux RAIDs is to start by reading the RAID meta data from each drive within linux. From this, not only will you know the RAID type, order and block size, but you should also be able to figure out which drive was the first to go offline and how long it has been offline.

[toooldforthiscrap]

@ Luke: Thanks for this. This one has 4 partitions, 3 very small and one main. I did manage to recover the RAID using UFS Explorer RAID. All okay. Thanks again.

[einstein9]

@ Luke: Thanks for this. This one has 4 partitions, 3 very small and one main. I did manage to recover the RAID using UFS Explorer RAID. All okay. Thanks again.

1- Boot
2- Swap
3- OS files
4- User Data (your shared folder(s)

[lcoughey]

@ Luke: Thanks for this. This one has 4 partitions, 3 very small and one main. I did manage to recover the RAID using UFS Explorer RAID. All okay. Thanks again.

1- Boot
2- Swap
3- OS files
4- User Data (your shared folder(s)

You got me there. I shall bury my head in shame. Wait a second! My comment still helped OP recover the data. I'll just pat myself on my back a little softer and then smack the side of my head for not being 100% accurate.

[toooldforthiscrap]

You got me there. I shall bury my head in shame. Wait a second! My comment still helped OP recover the data. I'll just pat myself on my back a little softer and then smack the side of my head for not being 100% accurate.

[einstein9]

All the best luck

remember working in VM Env. creating many RAID arrays (and gather info.) will certainly improve your skills in Raid Reconstructing

have a nice day all

[fzabkar]

http://www.r-tt.com/Articles/Finding_RAID_parameters/

[toooldforthiscrap]

http://www.r-tt.com/Articles/Finding_RAID_parameters/

Unfortunately, this only gives the parameters for Windows based RAID's. Most NAS are Linux based (as this one is), so its a little different. I have asked R-Studio to do a piece on NAS Linux as they are becoming very popular, but they have not got round to it yet. Many thanks for the input. I really appreciate it. I believe you are the PCB/Electronics Guru...... I may have many more questions for you over the coming months.....

[fzabkar]

http://www.r-tt.com/Articles/Finding_RAID_parameters/

Unfortunately, this only gives the parameters for Windows based RAID's. Most NAS are Linux based ...

I would think that similar principles would apply. You would still need to find the location of logical sector 0. I haven't examined too many Linux systems, but I would think that you would be looking for a sector with a partition table, and with a 55AA signature at the end, just as you would for a Windows system.

Here are two typical Linux MBRs (LILO and GRUB):

http://thestarman.pcministry.com/asm/mbr/GRUB.htm
http://thestarman.pcministry.com/asm/mbr/LILOmbr.htm

[hddguy]

http://www.r-tt.com/Articles/Finding_RAID_parameters/

I haven't examined too many Linux systems, but I would think that you would be looking for a sector with a partition table, and with a 55AA signature at the end, just as you would for a Windows system.

With many RAID systems the data volume starts at the position of the superblock which does not have a 55AA signature. Also, this superblock is located after the offset, in some units it is several hundred sectors after the offset.