Server raid questions!

I am planning on building a server that will have 3TB in a RAID 5.
I've built many computers although this will be my first server build.
The servers purpose is learning, web hosting, and computing.
I plan on running XenServer with at least 2 VMs consisting of Windows Server 2008 R2 and CentOS
I plan on using TrueCrypt for both windows and linux to encrypt all data.

• Never done RAID 5, only RAID 1... when doing RAID 5 will 3x 1TB HDDs show up as one 3TB partition?
• When I set up the VMs should each have its own partition in the RAID? Then each OS would handle encrypting its own partition?
• Should I opt for "shared storage" that can be accessed from any VM along with the VMs dedicated space?
• If I do have some form of shared storage what file system should I use for it... and how would I go about encrypting it so each VM can access it?
• Is a volume encrypted with a TrueCrypt algorithm readable from multiple OS?
• When I run out of space on the initial server and I have no more room for physical HDDs can I add additional storage as NAS?
• Will the above add on to my initial RAID 5 or will it be seperate?
• Is the above the best approach to adding additional storage?

Feedback to any or all of the above is appriciated!
4 answers Last reply
More about server raid questions
  1. Never done RAID 5, only RAID 1... when doing RAID 5 will 3x 1TB HDDs show up as one 3TB partition?

    Three 1TB drives in RAID-5 will give you only 2TB of usable space.

    If this is the only drive in the system then I'd advise against using RAID-5 because its very poor write performance will drag down the speed of all the other disk accesses in the system - this would be particularly bad in a VM environment where (I'm assuming) you'd have mulitple OSs trying to use the same slow RAID volume.
  2. Then perhaps RAID 10 would be better? Although this would require 4 drives correct?
  3. I suggest that your raid 5 array be a storage array, and not your system disk. This saves a LOT on monkeying around with drivers. Also, Raid 5 is (typically) not super fast.

    The amount of space given over for the parity drive is a whole drive (your usable storage is n-1 (n= number of drives)). Therefore, if you have three disks you will lose the equivalent of one disk of space. If you really want 3TB I suggest doing it with (5) 650GB drives or (6) 500mb drives. This way, you'll have more storage space available and also benefit from faster reads and writes.
  4. Ok so lets say I go with 5x 750GB HDDs in a RAID 5 to get 3TB. I would still need a separate drive for the VMs OS'.
    Lets say I were to go with 128GB SSD for OS'... I wouldn't have to setup partitions for each VM would I or is that something you allocate when setting up the VM? Is 128GB split between a few VMs too small? If so I won't be able to get a SSD due to costs.
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