Recreating logical volume

  • Last Post 26 November 2016
Stephen van Egmond posted this 25 November 2016

Hi, I have a Promise R4 that has suffered a the hands of an incompetent and needs to have the logical volume rescued.

The tech ejected all the drives while the system was off, brought it up with new disks and recreated a new array.

I need to revert back to the old array definition, very badly. I have imaged the raw data off the hard drives and am wondering how to approach this.

My thought it to put the new disks in, recreate an array in the same "shape" as the old one, power off, and if necessary overwrite the disks with the images I have. Bring it up, and the partition should be there. Right?

Question: does creating a logical volume or anything else *necessarily* write to the drives?  I would sooner it did not write a partition table or format a volume, just update the controller's definition of what the storage array should look like.





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Stephen van Egmond posted this 26 November 2016

Hi Richard-

Thanks for a very useful answer.  Yes, we have the drives as they were when the thing was powered off to switch to the new SSD.




We referred the drives for a second opinion from a recovery house. They have suggested my story is wrong: the drive was making 2tb out of a 4tb array because it was raid *6*.  The recovery people looked at it it various ways assuming raid 10 and it never came together. I would never set up a studio with raid 6 ... but the former IT folks kinda would have. 

I think resetting to raid 6 LV would be the next step in the morning.






R P posted this 25 November 2016

Hi Steven,

If you have disk images you should recover from those. Write the images back to the same size drives, and insert those drives into the powered off pegasus.

Restart the Pegasus. There are several possible outcomes.

1) The logical drive will be back online.

2) The drives may be in an inconsient state, they may show dead status or some other status, you may have to force them online.  

If your images were of the complete drive, then recovery is likely.



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