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Showing posts from June, 2015

Repeating questions

There is a set of questions which customers seem to be repeating perpetually,


We have a large fancy storage system which failed. Can we fix it in place, without copying data?

No, you can not. You absolutely have to copy the data away. Yes, this means purchasing the disk set of the same size. Yes we know full well that it is 50TB, meaning 13x 4Tb drives. Yes, plus a RAID controller for it.

Can we have a RAID5 recovered when two disks failed?

No, that won't work.

OK if we can get the RAID recovered, maybe we can just get 2/3rds of files, since we'are only missing a little bit? 

No,  that won't work either, because any file lager than block size will be broken.

So we still can get some small files?

There are surprisingly few useful small files when the value of small is defined by the RAID controller.

OK maybe we can get our Word/Excel files and repair them using whatever DOC/XLS repair tool?

No, that won't work. The data is missing, and when the data is missing, no fancy re…

Things to avoid in data recovery

This is a short list compiled based on the tech support experience,without much explanation

Avoid
USB-to-SATA converters (for bad reliability);Marvell chipsets (for bad handling of bad sectors);Silicon Image controllers or any RAID cards based on these (after SIL_QUIRK_MOD15WRITE; even if SIL_QUIRK_MOD15WRITE does not apply to your controller, this is not an excuse to use Sil);nVidia chipsets (for bad reliability of disk controllers under load)