replacing a failed disk on AX4-5i

First:  I do not have an answer to your question, but I have question(s).

The EMC disks use a 520 byte block...did the data recovery product you used understand that?  Because that is usually the biggest barrier to attempting the sort of repair that you are engaged in.

If it did not replicate the low level format of the disk, then you've got nothing.

Hi Zaphod,

Thanks for your input. Unfortunately, we have not gotten that far yet.

We only used ddrescue tool to image the failed drive. Now, we have images of all data disks from the RAID array.We are currently looking for any data recovery tool to recognize the data from the images. We are aware that the EMC uses 520 byte block for their RAID 6 implementation so we are looking for any tools that would be configurable.

We still think if we can force EMC shelf to take the new cloned EMC drive by changing the S/N of the array member, that will be the fastest way of fixing the problem. We haven't been able to find any references to that and we were looking for anyone who could help us.

Best,

Hitae

EMC Support does not know of any way to change the serial number of a disk in the Flare OS. Engineering might know a way to do that, but you'd have open a service request with EMC so they could open a case with engineering to see if that is possible.

For this to work, you'd have to have a bit for bit copy of the original disk. The disks are formatted not only in 520 bytes per sector but also with hidden partitions on the disk. These partitions contain a lot of the internal identification of the disk that must match to what the OS understands the disk to be.

glen

Hi Glen,

Thanks for your post. We tried to open up a service contract with EMC, but since we originally bought the unit from a reseller, EMC actually told us to go through the vendor to get the service contract. Besides that, there are some other bureaucratic reasons that we can't control that is delaying the process.

I think we copied the failed disk bit by bit to a new disk. We just need the EMC OS to recognize the new disk as a member of the RAID group. We see in the log that the EMC is complaining that the S/N of the new disk does not match the one that the system expects. So far, we could not find an easy way to update the system area of the disk which contains the S/N. Are there any other information that EMC checks to match the drive?

We found that we could get into an engineering mode on EMC Unisphere and someone in the community mentioned that S/N can be changed in this mode. However, we could not find any functions like that.

Best,

Hitae

I don't think you can get to the area in Flare that contains the serial numbers - that's an engineering process that we don't have access to.

glen