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I have a dell server with two 18 gig drives in a Raid 1 config. I want to replace the drives with 400 gig drives. If I break the mirror and then remove one of the 18g drives, insert a 400g and create the mirror, then do the same process again with the other 400g drive, what will I have? I would like to think I would have a new 400g raid 1 drive. But I seem to remember that this process might result in only 18g of useable space on the 400g drives. Anyone know for sure?


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Yah you will be left with 18...if you create a mirror between a 400 and an 18 you would get under 18 of usable space. You should backup and restore to your newly configured RAID. – Campo Jun 8 '10 at 14:07
What type of RAID 1 (what controller and what OS)? – ircmaxell Jun 8 '10 at 14:07
Are you sure your server can support 400GB drives? Most servers that supported 18GB drives used something like SCSI-1 or 2; and most 400 GB drives are more like SCSI-4 or SAS. – Chris S Jun 8 '10 at 14:08
BTW a 18GB backup should go pretty fast. Might be easier to simply make a image-backup and restore. Either way you should still make a backup if you don't have one. – Zoredache Jun 8 '10 at 16:29
up vote 0 down vote accepted

You will end up with two 400 gig drives that think they are 18 gig drives. But depending on the RAID controller be able to create another partition.

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Correct that is what happened but that was enough to keep it going until I moved all the data to a Hyper-V virtual server. – PBK Aug 1 '12 at 16:42

You'll have a 18GB mirror with 382GB wasted space. Make sure you wait for the array to rebuild before replacing the 2nd drive.

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Depending on the RAID it you may be able to extend the volume and use it after both drives have been swapped. – Zoredache Jun 8 '10 at 16:27

Thanks for the suggestions and info. Here is what I ended up doing. The server was a 6 year old Dell 2650 with a PERC 3i raid card or back plan? I used Clonezilla (awesome free tool) to make an image of the 18 gig mirror, it took about 2 hours to complete the image and store it on a USB drive. Some of the slowness was, I believe, due to the server only supporting usb 1.0. I then added the two larger drives and created a mirror which then required a scrubbing period. This ended up taking about 5 hours which was very painful to wait for. I didn’t think it would take that long to setup a two mirrored drives. The Dell Server Manager tool said I wouldn’t be able to write to the mirror until scrubbing finished. Once finished I pushed the image from the usb drive to the mirror using Clonezilla again but with the –r and –k1 settings selected in Advanced Settings. The reimage took about 2.5 hours and then it expanded the partitions (there where 2) proportionally to fill up the whole drive. I had some major issues due to a faulty cd drive in the server (which also wouldn’t boot from usb) but once Clonezilla ran it worked wonderfully.

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