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Replacing RAID controller without losing data

I have a faulty 3ware RAID controller that I need to replace.  I have a spare controller ready to use, it is the exact same model.  Is it possible for me to replace the faulty controller with the spare without losing data if i place the drives in the exact same position as they are in the faulty controller?

I have already created backups of my data.

All help appreciated.
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paulms53
Asked:
paulms53
2 Solutions
 
ks_adminCommented:
Short answer, yes.  The raid configuration is stored on the drives, but like you said, keep them in the same position just to be sure.

Also, although not techinically required, I always match up the firmware on the RAID controllers just to be sure.


ks_admin
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DavidPresidentCommented:
Yes ...
1) first upgrade or downgrade the controller's firmware (and controller's BIOS) to match that of the card that died.  This is VITAL.  Not all versions of firmware/BIOS/drivers are either upward or downwards compatible.

2) Unless you are 100% sure that the RAID was in no way degraded or in stress in any way, then the prudent thing is to do a full IMAGE backup of all disks using another computer.  Easiest way to do this is get yourself a large 2-3TB SATA drive, and plug in the 3WARE RAID disks.  Boot to linux, and then use dd command to image each physical drive into a data file, then compress the file.  
Is this required?   No, but always a good idea.  There is a remote possibility that you already had a metadata / NVRAM mismatch on the faulty controller.

If this was a healthy controller, then this step would be overkill, but sorry, when you have a faulty controller, all bets are off.
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Rodney BarnhardtServer AdministratorCommented:
This has been successfully done by replacing the card. Read the final comment at the bottom:http://arstechnica.com/civis/viewtopic.php?f=11&t=1125616

There also seems to be a lot of complaints about this controller, so you may want to reconsider this controller. Here is an article written by the president of a hosting company that used these: http://www.mattheaton.com/?p=160

Plus, the link above has several people commenting on problems with these cards.

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paulms53Author Commented:
I will need to upgrade the firmware on the spare controller card.  I already have backup of all of my data. I will be performing this switch later this week after business hours and keep you posted.
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DavidPresidentCommented:
Well, having a developers agreement with LSI/AMCC (In my day job I write RAID diags, appliance software, etc ...) I can comment in much more depth.  
1) The vast majority of "problems" that people have with these cards when using a parity-based RAID and desktop class drives.  If you don't have enterprise/server class disks and are running RAID5 or RAID6 then you are just asking for trouble due to the error recovery limitations.     RAID1/0/10 is safe on desktop disks.

It is profoundly rare that this family of controller is to blame. It is one of the better midrange controllers out there.   Also if you don't enable background scrubbing then you are just asking for data loss when you have a drive failure.

[Warning - getting on soapbox]
Personally if you are using desktop class disks and this controller, or any RAID controller with RAID5 or higher (and to some extent RAID10), then backup often.  Furthermore, if you have Intel Matrix, or LSI-branded, or HP SMARTArray, or Dell PERCs RAID controllers, then desktop drives aren't even supported, and I have a drawer full of t-shirts thanks to the people that don't read published specs and qualified disk lists who think that the only thing that differentiates 2 SATA disks of consequence is amount of RAM, Capacity, and RPMs.  
[Off of soapbox]
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paulms53Author Commented:
these are RAID 10 configurations on this machine.  unfortunately, (bear in mind, i did not purchase these disks) the disks in use are desktop class.
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paulms53Author Commented:
RAID controller went seamless.
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