Replacing hard drives in a Dell PowerEdge 2900

I have an older server, a Dell PowerEdge 2900 with eight physical hard drives installed.  I’m almost out of disk space, and have no more drive bays.  Admittedly, I am a bit of a novice when it comes to working with servers so bear with me please.  The eight physical drives are 146 Gigabytes, and I would like to replace four of them with 300 Gigabyte drives.  I already have the four 300 Gigabyte drives and they are new.

The eight existing drives are configured into one logical drive.  The Disk Management console in Server 2008 only sees them as one unit (Disk 0, Basic, 816 GB).  I rebooted the server to have a look at the RAID utility.  It comes up as PERC 5/i Integrated BIOS Configuration.  It shows as having seven physical disks, and then shows an additional disk designated as a Hot Spare.

I have read that I might could pull one disk at a time and have the server rebuild the volume on the replacement drives individually.  But I don’t know if it matters which disk I pull (since the RAID utility only lists one as a hot spare, and I’m not sure which physical disk that is).

I also read that the volume would only rebuild to the size of the previous drive, but that I might could use a partitioning utility to expand it, or at the very least create a second logical drive.  If that is my only option for expansion (meaning I can’t get Drive-C bigger than the current 816 Gigabytes) then I would be satisfied with that if I could then create a Drive-D and store files on that volume, although I would prefer to make Drive-C larger if possible.

So, what are my options?
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Don S.Commented:
This can work, but there are caveats.  First, when you replace the drives with bigger ones, you must do it one at a time and you MUST wait for rebuilding to complete successfully before replacing the next drive.  You must replace all drives with the same larger sized drives - including the hot spare (unless you don't want a hot spare afterwards - in which case you could just add the hot spare into the array right now and save yourself a bunch of time and expense) Once all drives have been replaced with the new bigger ones, you may be able to expand the existing array in place.  BUT, unless your Perc adapter has a battery backup option installed, it won't let you expand the array, it will only let you create a new array in the extra space or allow you to delete the existing array and build a new bigger one (not a great idea unless you like restoring servers from backup).  If your PERC is up to it, you would expand the array, then expand the Logical drive on the array.  Once that is done, then you would go into the Server and expand the partition(s).  Depending on the OS and how the partitions were setup initially, you may be able to use the windows disk management tool, or you may have to get/use a 3rd party tool to expand/move partitions in place.  As always BACKUP everything and verify your backup before undertaking any of this!
PowerEdgeTechIT ConsultantCommented:
No, this isn't going to work.

1. If you rebuild every drive with a larger one, the array will remain the same size, and there is no way - automatically or manually - to make it fill the entire size of the disks (at least not with the controller in the 2900). The ONLY thing you will be able to do with the new space is create a separate VD across the disks, which will be presented to the OS as a separate "disk".

2. If you only replace 4 of the disks with larger ones, you can do NOTHING with the newly available space. Nothing. It must be ALL of them.

3. You put your data at extreme risk rebuilding it that many times. I would recommend against it. Do a backup/restore to a larger array.

"I might could use a partitioning utility to expand it, or at the very least create a second logical drive"

NO partitioning tool can resize a hardware RAID array or create arrays (logical/virtual disks).

"Once all drives have been replaced with the new bigger ones, you may be able to expand the existing array in place.  BUT, unless your Perc adapter has a battery backup option installed, it won't let you expand the array"

The PERC 5/6 cannot expand "in place" after replacing disks with larger disks. You need an H7x0 controller do be able to do that. And the PERC 5/6 does not have a non-battery option, and it would make no difference on its ability to expand the array.
AaronSystems Administrator & DSTCommented:
This might sound overly simple but depending on the type of data... Can you get a large external drive (even 4TB isn't to hard to get a hold of) and move all the data to this drive and then try to recreate the raid setup on the server with the new drives and bring the data back over so long as the drive with the operating system and programs stays in (this might take a bit of tweaking).

My suggestion:
An easier way to expand the storage may be to have an external drive with a NAS like configuration for the server though performance may be an issue depending on the useage.

That would be the easiest solution and the fastest with more ability to change things around on the server once you have this going. I saw a newegg deal for an 4TB external drive for like $100 just recently so it's fairly cheap though again depends on how users will access this data etc. so you may have performance concerns.

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JABrownAuthor Commented:
Thank you to everyone for your input.  Based on the recommendations above, I acquired four additional 300-Gig drives, so I now have a total of eight.  Also, rather than try to rebuild the array, I may just start fresh with a new array and reinstall the O/S and restore my data, as was also suggested above.  Hopefully I will have time to do so within the next week.  I will update this post once I have done that and will allocate points accordingly.
JABrownAuthor Commented:
Sorry so long to post an update.  I have finished this project, and my server is running well with the new drives.  As suggested by PowerEdgeTech, I did acquire 4 additional drives to make all eight the exact same size.  And as suggested by Aaron, I moved all of my data to an attached storage device and then reconfigured the array with all eight of the new drives.  Yes, I did have to reinstall the Server O/S and the applications, which I did not originally plan to do.  But in the end it made for a much cleaner install, and I probably spent much less time doing that than I would have spent trying to replace & rebuild drives one at a time.  Thanks again to everyone for their input.
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