/Storage migration to new array - PDOS not detecting newly attached disks

[Abesama]

Hi PDOS (SuSE) gurus,

Recently I had to do storage migration from old array to new HDS.
PureDisk /Storage was configured with LVM.

I unmounted and exported the volume group, then storage people sync'ed disks to new ones.

Even after we reboot the PureDisk sever (all-in-one node) the new disks were not visible on the PDOS.

We had to echo "scsi add-single-device H B T L" to /proc/scsi/scsi but after another reboot, disks went missing again.

What do you think?

PureDisk is version 6.2

[scorpy_582]

Hi,

Could you please check and confirm if the size of disk (partition) coming from array is greater than 2TB.
If it is greater than 2TB, it could be a reason for not getting the disks detected.

[Tom_Burrell]

even though you can use volumes larger than 2TB, you can't present them that way.  You have to use 2TB or smaller physical volumes to build your larger logical volume.

Really annoying- but there you are.

[Abesama]

Hi Scorpy_582,
Thanks for your comment.

As I said, it's a volume group that is consisted with many of small chunk of disks that I exported earlier - each disks were approximately 60G in size.

Naturally, the new disks were about the same size each, consisting the volume group that I tried to import back in.

In other words - the situation I were in was not about OS seeing a disk greater than 2TB.

It was about the OS seeing disks with 60G size, and importing the same volume group back in - for which usually you do not need to do anything from OS side except making sure the new disks become visible.

I'm not an expert in this field nor I did this many times before, so I may be wrong in saying any of that, and if I am, please kindly correct me.

Cheers,

[Abesama]

Yep, we use LVM to glue many (30, 40 - lost count how many) of 50G/60G partitions to make up 3TB volume.

After we echo some "single device ..." parameter to /proc/scsi/scsi, the disks came visible again - I think this pretty much tells us that the OS "can" detect it, but it was not willing to do so until we whipped it, for some silly reason?

:)

[Abesama · Accepted solution]

Hm ... it seems no more opinions to this question.
I'll just close it as it is then.

Just a note - we are going to try pvmove for the migration next time.

Abe

[emad964]

even though you can use volumes larger than 2TB, you can't present them that way. You have to use 2TB or smaller physical volumes to build your larger logical volume. Really annoying- but there you are.

[diaboliq]

Such a big change is hard to do and it does not come without problems i mean great Self Storage is so hard to find a reliable source

[cyclone]

Yes such as large transfer can cause problems, unfortunate that no one could help you with this. I would be interested to hear a sounds solution to this.

Mike
















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