Windows Server 8 Hyper-V and Storage Experiments

It’s been a while since my last post! I guess I was waiting to have something interesting to write about and share with my fellow techies. The guys in my team at Global Excel Management are aware that I’ve been having a lot of fun (not!)  getting my storage project going. Let’s just sum it up that 3rd time was the charm when it came to the LSI 9265-8i controller that is part of my experimental server. I’ve encountered stability problems with 2 controllers which delayed the experimentation project but it was worth the wait.

Here are the current specs for my test servers:

Main storage server
Supermicro chassis with
2 x Intel Xeon X5650
12GB RAM
LSI 9265-8i RAID Controller
20 x 1TB SAS drives splitted in 2 RAID5 volumes of 9 disks each with 2 global hot spares
4  x 120 Intel 320 SSD with 2 of the drives are currently assigned to LSI CacheCade (SSD read cache)
Windows Server 8 Developer Preview with the following:
Hyper-V Role
File Services Role with Data Deduplication

Replication server
HP BL460C G6
1 X
18GB RAM
1 x 40GB volume on EMC CX3-40 SATA drives as boot volume
1 x 200GB volume on EMC CX3-40 SATA drives as data volume
Windows Server 8 Developer Preview with the following:
Hyper-V Role
File Services Role with Data Deduplication

Storage VM
1 VCPU
2GB RAM
1 IDE controller with the OS drive connected to it (VHDX)
1 SCSI controller with a data drive connected to it (VHDX)
Windows Server 8 Developer Preview with the following:
File Services Role with Data Deduplication and ISCSI Target

Here’s an idea of what the stack looks like:

  1. Storage is hardware agnostic
  2. Hyper-V Replica allows me to replicate the ISCSI volumes to another host for failover capabilities without clustering the physical hosts with a configurable number of snapshots
  3. Storage can be expanded in multiple ways at different levels:
    1. Add more drives in the physical host
    2. Add storage enclosure to the physical host
    3. Mount volume from another host/storage array and assign to the storage VM (could be iSCSI, FC, SMB)
  4. Can use standard tools to backup the storage VM or the physical host
  5. I get IO caching through the LSI controller cache and through the CacheCade feature which uses SSDs for the read cache.

One thing I would like to see changed in upcoming releases of Windows 8 are the following:

  • Currently, you cannot failover a Hyper-V Replica VM without downtime as the VM needs to be turned off before the failover.
  • If I add a new VHDX to the VM, I need to drop the replication and reconfigure it. For large VHDX, that is a bit of a turn off!

Problems encountered:

When I was pushing a lot of write IO to my VM, replication became out of sync. Resynchronizing was an easy task but still. I’ve not enabled automatic synchronization on the VM and after a test I didn’t encounter the issue I experimented initially.

You may wonder what kind of performance I’m getting out of all this. The performance is actually pretty good. I’ll publish some stats in an upcoming post.

One thing I may experiment with in the future is the use of Windows Server 8 Spaces to potentially remove the need for the RAID controller. Unfortunately by doing this, I would lose the controller caching capabilities (SSD and controller cache).

I’ve done some testing with ESXi 5 but I haven’t found yet a good combination to expose the storage. I’m still investigating NexentaStor and other alternatives where I could do the replication from within the appliance. One thing that bugs me is that there’s no way to manage the RAID controller from within ESXi. I’m not sure also how the hardware errors are surfaced in ESXi (i.e. disk failures)

More on my tests with storage to come!

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2 thoughts on “Windows Server 8 Hyper-V and Storage Experiments

  1. NexentaStor doesn’t do Application aware snapshots (agent based) which really limits the ability to replicate Databases and VM’s. They also don’t support SMI-S and have issues with CSV. I want to like Nexenta, they just aren’t quite there.

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