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Raid 5 Rebuild

I have one clients that is running Windows 2003, Exchange 2003, AD, Print and file services from a single RAID 5 (three 9GB HDDs) on a Dell PowerEdge 6350.

They have ran out of space and we need to put in new drives. We back up Exchange and the file shares, But I am not sure how to put in the new drives and rebuild the array without losting AD, Exchange, Windows, ect. Maybe it would be easier to buy a NAS or locally attached device?

Any ideas would be appreciated.
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Justin Durrant
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Justin Durrant
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3 Solutions
 
Duncan MeyersCommented:
Your approach depends on what hardware you have:

Which PERC controller do you have, and what is the driver/firmware revisions?
What size HDD's do you want to go to?

Getting new and larger HDDs into the array is fairly straightforward - you just aren't able to access the additional space from your existing 18GB partition. You'd need to create a new partition (or container if the RAID controller is an Adaptec) and move your data onto the new partition.
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Justin DurrantAuthor Commented:
Whew. This is good news. I will find out the controller details and post them later. I am thinking of going with three 36gb drives. Thx.
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rindiCommented:
Get more than 3 drives. Raid 5 works faster with more drives, and you'd probably have the same problem again soon if don't make the diskspace large enough right away.
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Carlo-GiulianiCommented:
Rindi, I think the Dell 6350 has only 3 hot-swap bays.  Is that right, jjdurant??  If so, you do have a problem.

The easiest thing is going to be to use and external disk array.  You probably have an external SCSI connector on your server, so you won't need an intelligent array or a new SCSI adapter...you want a JBOD box, which means "just a bunch of disks".   An example is a Dell Powervalut 22Xs.  There is a 200S with 8x73GB disks already installed on eBay right now for only US$700.  If I were you, I would grab it.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1484&item=5773850333&rd=1


You might be able to use a NAS box, but Exchange is very fussy about where you put its storage.  Some NAS boxes are supported for Exchange storage, but they are usually high-end boxes.  I doubt it is worth the trouble for you.

If you don't want to use an external storage unit or a new server, then you are looking at a complete backup and restore.
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Justin DurrantAuthor Commented:
Yep only three.

So I can't make meyersd solution work with my three bays?
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Carlo-GiulianiCommented:
As I understood meyersd, he was saying you can install new drives, create a new partition on them, and then move data to the new partition.  True enough, but how can you install new drives if your hot-swap bays are all full??  You *cannot*  remove a drive and replace it with a bigger drive without erasing all data.

So, you need an external disk unit (or a new server).

Once you have an external disk unit and a new volume, you will have many options:
 - move data to the new partition (as suggested by meyersd)
 - make your disk "dynamic" and extend an existing partition (but you can't do this with the C: volume)
 - use a junction point to mount the new volume as a directory in an existing volume



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rindiCommented:
Depending on the capabilities of your raid controller, it may be possible. replace the first disk with the new one, then wait until the array has been fully rebuilt. Once that is OK, repeat the above step with the 2nd drive. Again, once the array has been rebuilt, replace the last drive. Now again when the array is fully functional, you can use the array management software to "expand" the array to the full capacity of your new disks. Since I don't know the perc controllers used by Dell I don't know if your controller has this option. Please tell us what perc controller and what firmware it is using as Meyersd asked, this should tell us if this is possible with your current hardware.
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neoponderCommented:
It is possiable on all current Dell Perc Controllers to do what Rindi suggested, and I have done this many times.

Just remember that rebuilds *useally* work.  I managed around 200 Dell and IBM servers and I have had rebuilds fail on both  systems using PERC and IBM Netraid.  

Make sure you are prepared to restore from tape before you attempt this!  

Also, if you can afford and external array, you could save yourself alot of trouble.  Check your current raid controller, how many ports does it have?  If one is free all you have to do is buy the enclosure.  Then you can create a second Raid 5 in the external enclosure.

You your existing drives as a mirror for the OS, and then by at least 2 more for mirror, and 4 for raid 5.  

Best practice for and exchange server for performance:

1x Mirror for OS & static Exchange Data files  (c:)
1x Mirros for Logs (d:)
1x Raid 5 fore EDB files. (E:)

I have one exchange 5.5 server setup this way on windows 2000 with around 500 users, and it is Very fast.  



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Carlo-GiulianiCommented:
Hmm....theoretically possible.  But I haven't seen any product documentation that claims to support this method.   I would not try it with clear support from the RAID controller vendor.
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Carlo-GiulianiCommented:
OK...more than theoretically possible (neoponder must have posted while I was typing).   But he also confirms it is risky.   I would go with the external array.
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rindiCommented:
Normally it shouldn't a problem, you should find help in the perc's manual (maybe you need to download it). I've done this a couple of times with the smartarray controllers (different types) used in compaq servers, and never had a problem there. Why should Dell Servers be different?
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Justin DurrantAuthor Commented:
Guys, here is the controller I am running:

Dell PERC 2/DC
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rindiCommented:
According to the specs of this controller, it is "online expandable", so that should work without problems:

http://support.dell.com/support/edocs/storage/RAID/66JVW/Features.htm#Chapter4

Also make sure you install the new management software

http://search.dell.com/results.aspx?cs=&sum=True&s=gen&ssum=False&k=perc+2%2FDC&cat=all&img=True&l=en&qmp=10&c=us&snpsb=K&snpsd=D&subcat=sup%2Fdyd&usf=&ddate=False&rfe=false&p=2

and the newest firmware. When upgrading the firmware make sure you have read the instructions

http://search.dell.com/results.aspx?cs=&sum=True&s=gen&ssum=False&k=perc+2%2FDC&cat=all&img=True&l=en&qmp=10&c=us&snpsb=K&snpsd=D&subcat=sup%2Fdyd&usf=&ddate=False&rfe=false&p=3


Of course, as already has been mentioned, make a backup and test it before any manipulation (although I'm assuming you are doing that anyway, as a good backup is the "A" and "O" of good IT practice!).
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Duncan MeyersCommented:
> According to the specs of this controller, it is "online expandable", so that should work without problems:

Yes, but...

The on-line expandable in a PERC 2/DC means that you can add an additional disc and the array will expand onto the disc - for example - if you have a 3 x 9GB disc RAID 5 array and you add another 9GB disc then online expansion will (eventually - it is s-l-o-o-o-w) give you a 27GB array. You'd then need to run diskpart.exe (or similar) to expand the Windows partition.

What I'm not sure about is whether or not you can add another RAID partition to use the additional space. As a PERC 2/DC is an old AMI card, you cannot expand the existing partition to fill
the extra space...
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Duncan MeyersCommented:
I've been going trough the documentation - with the docs available there is no indication that a second RAID partition can be created on the existing RAID set.

Upgrading the PERC 2/DC firmware may provide you with the added funcyionality needed, but I doubt it. Dell lists mostly bug fixes for the later revisions of f/w.

If you were to use the hardware that you have (with new discs) you'd need to blow away the existing RAID configuration and create a new RAID 5 set - which is going to be a bit of work for you.

The idea of using a 2nd hand rack of disc connected to your PERC 2/DC is a good one - and would be cheaper than buying three brand new 36GB discs.
Using the ebay box as an example, you could set up a 4 disc RAID 10 set on the external discs which would give you plenty of room and loads of performance
and plenty of spare discs for when they inevitably fail (I suspect that you might have some trouble getting h/w support from Dell for an old PV200S now so you need
to consider parts availabilty).

So, sorry to be the bearer of bad news, but what you want to do is not going to be quite as simple as it first seemed.

 
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Justin DurrantAuthor Commented:
Thanks guys.. I think an external JBOD is my answer. I don't want to risk losing anything and having to rebuild from scratch. I will split points if that is ok?
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rindiCommented:
No problem, thanx and good luck expanding.
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