Newbie RAID Questions

[no1youno]

Hi all

I recently picked up an old Proliant ML370 that I'm wanting to use to replace my current "server" that is just a desktop.
Before I start on the ML370 I was hoping someone could please clarify some things on RAID. Firstly, all I know on RAID is what I have researched in the last week, and believe that the best for me would be RAID-0 and RAID-1.

If I create RAID-1 with 2 of the 6 disks as Drive C:, and 2 for Drive D:, is it possible to create RAID-0 for the last 2 disks which will be drive E:
Also, can partitions be created on these three logical drives, even the 2 disks (drive E on RAID-0?
Lastly, is it possible to do an image backup of drive E: (RAID-0) using something like Ghost or Acronis even though its "striped" to 2 disks?

Thanks.

 

[cajuntank]

I would never do RAID0 since there is no redundancy whatsoever. RAID0 just sripes the data across multiple drives. Having just one of those drives fail means you have lost the entire RAID0 set. Depending on what you are going to be using the server for, I would follow the basic guideline of a RAID1 mirror pair for the boot OS, then the remaining 4 drives in a RAID5 setup. This will stripe the data and a CRC checkbit across the drives giving you the capability to lose one drive and still function till you get it replaced. You could also choose to do RAID5 with an online spare. This uses one of the 4 drives as a online spare so that you could lose two (not at the same time however) and still functions. In a RAID5 set you have to have a minimum of 3 drives and your total drive space is total amount of drives minus one (i.e. 3x72GB drives give you an array of 146GB using RAID5; 4x72GB drives gives you 216GB using RAID5; 4x72GB drives gives you 146GB using RAID5 with online spare).

If this server will also do Exchange or SQL, etc... then follow recommended guidelines for those (i.e. RAID1 for OS, RAID1 for logs, RAID1 for database).

If the RAID is based on hardware controller and not software, then Ghost or Acronis will only see the logical drive and not the physical drives within the array.

 

[no1youno]

If the RAID is based on hardware controller and not software, then Ghost or Acronis will only see the logical drive and not the physical drives within the array.

If I am unable to use Ghost or similar, how do I backup? Or do I just rely on the mirror on RAID1

Also, can I add a HDD while the server is still running? Is this what is called "Hot Swapping"

Thanks

 

[cajuntank]

You are able to use Ghost or Acronis because they will see the logical drive and not have to peer into the physical drives...this is a good thing since each controller maintains different characteristics on it's controlled array (Ghost or whatever doesn't have to know about all of that).

Hot swapping is the ability to unplug a drive and plug back in. Normally this will be to replace a failed drive with a good one. Adding another HD in a RAID1 array setting would actually require you to add 2 drives since the RAID dictates mirroring. In RAID5, you could add just the 1 drive. Both RAID scenarios would then require you to expand the array to use the drive(s), see your controller's documentation, then you would have to deal with adding that new free space to your OS.