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View Full Version : [ubuntu] raid 5 with 2 1.5TB disks then add a 1.5 with data?



speed32219
March 12th, 2010, 05:54 AM
current setup is Karmic 2.6.31-14-server in older spare PC strictly home server for htpc (ISO's, WAV, Pictures and home videos). I have 2 new-1.5TB drives that are not installed yet and another one that is installed with 900GB of data on it.
df -h
/dev/sdb1 1.4T 878G 429G 68% /media/disk-1 1.5TB
/dev/sdc1 459G 120G 317G 28% /media/disk-2 500GB
/dev/sdd1 925G 627G 251G 72% /media/disk-3 1TB

I have two new 1.5TB disks (1 WD WD15ARS and 1 Samsung F2 HD154UI)
After having a 1.5TB WD disk one month ago die on me plus a 320GB went out 2 months earlier I decided it was time for some form of protection.

Questions:
Can I install the two new 1.5TB disks as a degraded Raid5 with LVM, then copy the data from /dev/sdb1 (890GB) to the new degraded raid. Then just grow/add to the array the /dev/sdb1 (1.5TB that I just copied the data from) and redo the partition to raid5 + lvm?

Or, install the 2 new 1.5TB drives and create two 700GB raid5 partitions with LVM per drive. Then copy the data from /dev/sdb1 into the array and then set it up with two 700GB partitions w/LVM also, then copy the data from the 1TB disk into the array?

Just wondering, because of the physical size of the HD, if it would be better to have multiple partitions per drive.

Ellhound
March 12th, 2010, 08:29 AM
Option 1 will work just fine. Create a degraded array with the new disks, copy data to it, and then add the third disk.

speed32219
March 12th, 2010, 09:52 AM
Thanks, that's what I'll do.

Just wanted to be sure, it gets a little confusing reading all this stuff.

cascade9
March 12th, 2010, 01:02 PM
Mixing and matching HDDs for a RAID array is possible, but never reccomeneded. If your WD drive is a EARS (which I assume it is, they come in EARS and EADS versions now) I'd be extra carefull and double-check before even trying this with it . WD EARS use 4K sectors not 512B. Using an unaligned EARS drive can give a major performance drop. On a RAID system this could affect the whole array. I dont know how RAID will deal with drives of different sector sizes....you could have major issues.