HyperV Server - Raid Best Practices

pmoncho

@Joel said in HyperV Server - Raid Best Practices:

This got a little heated :face_screaming_in_fear:
-So can we clarify, back to the OP - Consensus out of the options I have, Option 2 is the best way to go?

6x 2TB 12GB/s Drives in OBR10 for everything and then creating two partitions (1 for the HyperVisor OS) and then (1 for data - to store all my Virtual Machines and Data).

My VMs would be in D:\Hyper-V\VM's
My Virtual Hard Disks (daily data) would be in D:\Hyper-V\Data

Don't forget to do the cost comparisons of SAS in OBR10 vs SSD in RAID5. You may be surprised to find out that SSD in RAID 5 is cheaper (Stick with SSD 6Gb/s vs 12Gb/s) depending upon your server manufacturer.

1337

Failure rate on harddrives are 2-3 higher than enterprise SSDs. Only reason to use hard drives today are price per GB and then use as few drives as possible.

I'd put all the VMs on one raid 1 SSD and keep the file server files on another RAID 1 with hard drives. Preferably 3.5" if you need lots of storage.

3 Windows server VMs, 1 host and SQL database files shouldn't take much space. 2x240GB or perhaps 2x480GB will suffice for that. Then the 2x4TB or however big you want to go for the file server storage. 12TB enterprise drives are readily available today, around $400 ea.

Option 3:
2 x 240GB SSD (for everything except below, 2x480GB if needed)
2 X 4TB HDD (for file server storage)
RAID 1 arrays. SATA will suffice for everything but for some drives SATA and SAS are priced the same so use whatever.

PhlipElder

@Joel said in HyperV Server - Raid Best Practices:

Hi guys.
Im drawn between two setup scenarios for a new server:

Option1:
2x 240GB SSD Sata 6GB (for OS)
4X 2TB 12Gb/s (for Data)
I was planning on using Raid1 for the OS and then Raid5/6 for the Data storage

Options2:
6x 2TB Drives in OBR10 for everything and then creating two partiions (1 for OS) and (1 for data).

Is there any better options? What would you do.

Environment will be Windows running. The server (bare metal) will run HyperV Server and the data drive will home 3x VM's (1x SQL, 1x DC and 1x FileServer).

Thoughts welcomed and appreciated.

I suggest using PerfMon to baseline IOPS, Throughput, Disk Latency, and Disk Queue Lengths on the current host to get a feel for pressure on the disk subsystem. That would make the decision making process a bit simpler as the future setup could be scoped to fit today's performance needs and scaled a bit for tomorrow's needs over the solution's lifetime.

EDIT: PerfMon on the host also has guest counters that can further help to scope which VMs demand what.

black3dynamite

Wouldn't it best to use the SSD for things like caching, page file?

DustinB3403

@black3dynamite said in HyperV Server - Raid Best Practices:

Wouldn't it best to use the SSD for things like caching, page file?

Often times yes.

But the conversation isn't about where to use an SSD, its if an SSD hypervisor is the better option of an SSD OBR5/10 hypervisor.

PhlipElder

@black3dynamite said in HyperV Server - Raid Best Practices:

Wouldn't it best to use the SSD for things like caching, page file?

Neither the host nor the guests should be paging. If they are, then there is a problem with the way things are set up host wise or in-guest resources wise.

scottalanmiller

@PhlipElder said in HyperV Server - Raid Best Practices:

@black3dynamite said in HyperV Server - Raid Best Practices:

Wouldn't it best to use the SSD for things like caching, page file?

Neither the host nor the guests should be paging. If they are, then there is a problem with the way things are set up host wise or in-guest resources wise.

But there should be a file for emergencies.

Carnival Boy

I think @PhlipElder's point about the difference in cost between small capacity SSDs and spinning disks is a good one. So if you're going to create a separate RAID1 for the OS on small disks, why not buy SSDs?

Apart from anything, the failure rate on them is much lower, isn't it? The labour cost of replacing failed disks often isn't trivial. It takes me over an hour per disk.

So the issue becomes should you install the OS on a separate array with small disks, or on OBR10? I'd argue that any disks under 250GB should always be SSDs.

PhlipElder

@scottalanmiller said in HyperV Server - Raid Best Practices:

@PhlipElder said in HyperV Server - Raid Best Practices:

@black3dynamite said in HyperV Server - Raid Best Practices:

Wouldn't it best to use the SSD for things like caching, page file?

Neither the host nor the guests should be paging. If they are, then there is a problem with the way things are set up host wise or in-guest resources wise.

But there should be a file for emergencies.

Run on the host/node in elevated CMD:

wmic.exe computersystem where name="SERVERNAME" set AutomaticManagedPagefile=False
wmic.exe pagefileset where name="c:\\pagefile.sys" set InitialSize=4199,MaximumSize=4199
shutdown -r -t 0

The double slash is required.

For standalone hosts we set 8192 instead of 4199.

Either MiniDump or Active Crash Dump is set. That's about all the page file would be used for is helping to produce those dump file AFAIK. A full dump would require a full page file equal to installed RAM. That's nuts when we're deploying hosts/nodes with 512GB to 3TB of available RAM on one node.

Dashrender

@scottalanmiller said in HyperV Server - Raid Best Practices:

@PhlipElder said in HyperV Server - Raid Best Practices:

@black3dynamite said in HyperV Server - Raid Best Practices:

Wouldn't it best to use the SSD for things like caching, page file?

Neither the host nor the guests should be paging. If they are, then there is a problem with the way things are set up host wise or in-guest resources wise.

But there should be a file for emergencies.

Ok this is something I don't understand then Windows still has a default paging file... are you saying that in typical use it's rarely actually touched? When I've looked at task manager I frequently see that the system is writing to the page file but the RAM itself is only half used or so..

scottalanmiller

@Dashrender said in HyperV Server - Raid Best Practices:

@scottalanmiller said in HyperV Server - Raid Best Practices:

@PhlipElder said in HyperV Server - Raid Best Practices:

@black3dynamite said in HyperV Server - Raid Best Practices:

Wouldn't it best to use the SSD for things like caching, page file?

Neither the host nor the guests should be paging. If they are, then there is a problem with the way things are set up host wise or in-guest resources wise.

But there should be a file for emergencies.

Ok this is something I don't understand then Windows still has a default paging file... are you saying that in typical use it's rarely actually touched? When I've looked at task manager I frequently see that the system is writing to the page file but the RAM itself is only half used or so..

You should also rarely use Windows