[Leica] OT: RAID Question

[rgacpa at yahoo.com (Bob Adler)]

Thanks John!
 Bob Adler
Palo Alto, CA
http://www.rgaphoto.com




________________________________
From: John McMaster <john at mcmaster.co.nz>
To: Leica Users Group <lug at leica-users.org>
Sent: Sun, October 31, 2010 12:54:16 PM
Subject: Re: [Leica] OT: RAID Question


> I'm hoping some of the more tech savvy folks can help me out here. I'd 
> like to
> upgrade my Drobo from 4x1TB drives to 4x1.5TB drives. 

In RAID 5? i.e. you can lose one drive and it keeps going

> If I pull all my drives at once, if anything happens to the new 4x1.5TB 
> drive 
>setup, I can put the 4x1TB
> drives back in. 

I doubt the RAID is that clever, it will have been reconfigured for 4x new 
drives. Server RAID can do this but I doubt "consumer" hardware can.

> That will put me back to where I was before I upgraded. I could keep the 4 
> old 
>drives offsite too, which would 
>
> help.

You would need exactly the same kit, (hardware/firmware etc) and even then 
may 
not work as above.

> But then I would need to temporarily store the data on the current setup
> somewhere, which is a bit over 2TB. I don't have anywhere to put this data
> temporarily. If I switch the drives 1 at a time, then I can't save the 4 
> old
> drives as a backup; they'll reconfigure where the data is stored each time 
> I 
>add
> a new 1.5TB drive.

Each time you change a single drive, the other 3 will rebuild the missing 
parts 
from themselves. You have the danger of one of these 3 failing before the 
4th is 
configured.... You will know at each stage that things have worked before 
moving 
to the next disk, expect quite a few hours per disk and I would leave a 
couple 
of days between disks. Do not expect to go backwards, perhaps get a couple 
of 
external 1.5TB disks to backup all the data during the transfer just in case?

john



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