A simple (hopefully) RAID question

[Chris S]

Proliant server with 4x2Tb Physical drives.

I want to use RAID0+1 (onboard controller supports it)

Do I set up two logical volumes of two disks, or one logical volume of four disks? It'll have Windows 2008 R2 Standard, FWIW; probably partitioned with two partitions so C:\ has the OS and D:\ has everything else (almost entirely Hyper-V vms).

[Biggsy]

*Post deleted*

Sorry, I think I got part of it wrong.

[Biggsy]

Take 2:

Presumably, your RAID controller handles the combination of RAID 0 and 1 for you.  RAID 0+1 needs more than two disks, so you want one logical volume of four disks (or more than one volume on the four disks, if you like and can).

[Chris S]

Take 2:

Presumably, your RAID controller handles the combination of RAID 0 and 1 for you.  RAID 0+1 needs more than two disks, so you want one logical volume of four disks (or more than one volume on the four disks, if you like and can).

Marvellous. Thanks 

[Biggsy]

ps.  The Intel RAID I've used calls its creations "arrays" rather than "volumes".  (Unless I've forgotten that it also calls them "volumes", confusingly).  After RAID setup, each array appears as a single blank disk to the operating system, then you put on the volumes (partitions) you want in the normal way.

[Chris S]

Got there in the end - it was quite tricky balancing the logical volumes with partitions that Windows Server would install on. Part of the problem was HP's Active Provisioning - a "friendly" BIOS UI that aims to install the best configuration. Well, I'm sorry HP - but I didn't want 2Tb for the OS partition  .

Eventually found a compromise; Windows is on a 250Gb partition, and there are two data partitions; 2Tb and 1.5Tb.

It is much much faster than the previously un-RAIDed setup, which was horribly I/O bound when running multiple VMs.

[hazeii]

All sounds good, that's what Proliants do (at least the fundamental raid part, it's up to the OS to make it seem complicated).

Normally though you run 5 disks - 4 in raid0+1 as per above, plus one hot standby.

[Chris S]

Normally though you run 5 disks - 4 in raid0+1 as per above, plus one hot standby.

Ah - OK; I assume that's what the ACP software refers to as "spares" in an array?

I got the impression you could add one after the fact, in which case I might - though I'd have to use a carrier in one of the 5.25 bays as the ML310e only has 4 3.5 bays.

[Biggsy]

Blimey, four disks is noisy enough, innit?, let alone five or six.  Though I suppose you're not sitting next to your server all the time.

Were SSDs out of the budget?  One or two of them would have been good for the OS at least.

[Chris S]

Blimey, four disks is noisy enough, innit?, let alone five or six.  Though I suppose you're not sitting next to your server all the time.

Were SSDs out of the budget?  One or two of them would have been good for the OS at least.

The noise isn't too bad, and the machine keeps me warm - I don't need any heating on during the day .

I work in a completely virtualised world, and have well over fifty VMs of various vintage and configuration for support, development/build, and testing. This is all great - it's transformed how I work in the last five or six years, but a VM server needs a metric fuck-tonne of disk space and memory. I dread to think how much 8Tb would have been in SSDs, but I'm fairly sure it would have been much more than the £50 each I paid for the spinning drives.

[Biggsy]

Yeahbut you could have SSDs just for the OS partition(s).  They're getting cheaper all the time, so if it's not yet affordable for you, it will be before all that long.  But then you'll have to spend more on heating.