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I have RAID10 configuration with 6 HDD running on Dell PowerEdge 1950 via Powervault MD1000. I want to add two more hard drives to the array so the initial RAID10 will turn to one with 8 HHDs. Is it possible without rebuilding the whole array and losing all the data on it?

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Your question and title are inconsistent. Do you simply want to retain the data or do you also want to keep it on-line, meaning you want to add the drives without powering down? – John Gardeniers Nov 12 '09 at 20:55
+1 Good question. I would think it would work very similar to the way you expand a Raid 5 array on a poweredge, which is done while online, but I'm curious to see an answer from someone who has tried. – Aaron Nov 12 '09 at 20:57
to John Gardeniers, I want to add two more drives to RAID10 array without restart or data loss. Restart less critical but data loss is. – eugeneK Nov 12 '09 at 21:05
I hope you mean data loss is inconvenient and not actually "critical" ^^ – Oskar Duveborn Nov 13 '09 at 0:13
It depends on the RAID card you're using - can you add that to the question description? The 1950 can come with a few different cards, and the exact steps will vary on the card. – Brent Ozar Nov 13 '09 at 2:28
up vote 2 down vote accepted

should be possible, using OMSA. go into the raid controller configuration, and look for a drop down box that has the "reconfigure" option under the logical disk that is your raid10

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I don't know why this answer is accepted. I didn't see "reconfigure" option under the logical disk. And DELL support told me that "Spanned virtual disks such as RAID 10, 50, and 60 cannot be reconfigured" – Sep 22 '15 at 20:57

i believe your server raid controller has Online Capacity Expansion feature- check your documentation.

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-1 RTFM isn't a good answer. – Aaron Nov 12 '09 at 20:58
That wasn't an RTFM, he told him exactly what to look for in the docs. – phoebus Nov 12 '09 at 23:57
I agree with phoebus -- the key to look for here is "online capacity expansion", a feature that most enterprise hardware RAID controllers provide. – John Röthlisberger Nov 13 '09 at 12:28
andrws and John Röthlisberger, maybe my question was wrong. I know that on the paper you can do that but my question was from your experience not about ability... sorry for misleading question. – eugeneK Nov 13 '09 at 16:20

Just remember, when Adding disks to RAIDs (online or not) it's a good idea to add one drive at a time, let the RAID to its thing and then add the next. I had a server halfway offline for two days while the raid rebuilt after adding two 500GB disks into a RAID5 array. Good thing I did it on a friday afternoon...

Your RAID should be extendible online, but double-check your backups anyway, before starting.

Note to self: Must thoroughly read question. Sorry.

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In raid 10, you add capacity with pairs of drives at a time. – Brent Ozar Nov 13 '09 at 2:28
Which doubles the the time to have both HHDs online – eugeneK Nov 13 '09 at 9:23

I know this is an old thread but I was recently researching the same subject and need to expand a raid 10 with two additional drives. Unfortunately the definitive answer at this time is no.

This is an excerpt from the Dell Controller manual:

"An online virtual disk can be reconfigured in ways that expands its capacity and/or change its RAID level. Spanned virtual disks such as RAID 10, 50, and 60 cannot be reconfigured."

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You cannot expand Raid 10 (50 & 60) without redoing the array.

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Can you indicate why? Some controllers have the ability to do this including many Dell controllers. – Dave M Jan 31 '13 at 14:54

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