James Bensley wrote:
I have some questions regarding a new home server I am going to build in the hopefully very near future (ASAP, I just need to finish planning everything and this is the penultimate hurdle), I will be creating a software RAID...
Lets say I have three drives "knocking" around which are all 1TB SATA II drives but each made by a different manufacturer. I am going to guess that these couldn't be used in a RAID 5? Or could they?
However could a similar result of 2TBs of data with redundancy be achieved with JBOD?
If you use software raid to combine the JBOD's, yes.
Also regarding RAID 5, three drives of data to one for parity is the max ratio I believe? I.e. to expand this by adding another data drive, the original parity drive would no longer cover this and another would be required, is this correct?
Yes, but if I were doing it I'd either run 2 drives in RAID1 or get another drive and either have 2 RAID1 mount points or a RAID 0+1. The advantage of RAID1 is that you can recover the data from any single disk and it still runs full speed even with a missing disk. RAID5 works but there is a performance hit and a big one when a disk is bad.
One more question about hot swappable drives, I understand that you can create RAID arrays with and without hot swappable drives but I am confused by this concept. I'm my experience with RAIDs I have only every delt with a RAID 1 that has degraded. I simply set the drive as offline, replaced it, set it to online and the RAID rebuilt itself all without restart the server and operation was never interrupted. So we can presume the server had hot swappable drives enabled yes? (It was a hardware RAID). With a software RAID is this still achievable?
Sata drives all but a few controllers are designed to be hot swappable but you need a special drive bay that permits swapping. It probably doesn't matter for a home server where you can shut it down for repair anyway. With software raid, after the drive is recognized (either hotswap or reboot) you need to fdisk a matching partition and then use an 'mdadm --add ...' command to sync a new drive into the raid.