Hyper-V Core + SBS 2011 Hardware Best Practices

StephRu
StephRu used Ask the Experts™
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Hi all,

I know this is the kind of topic that pops out several times a day, but what can I say, I need experts' advice :).

I would really appreciate your advice on the following setup and feel free to criticize any points. No budget has been yet set, but I would like to stay in the mid-range price of a server.

This is for a little network of 15 users. No Sharepoint, no database applications except what SBS and the anti-virus use. The data is going to be on a Raid-5 NAS, connected through iSCSI.

I was thinking of taking a HP ML350 G8 Tower with 24 GB of memory. It has a E5-2620 6-Core 2.0Ghz processor and a P420i raid controller with 512MB.

Here is my idea for the storage (remember, it's a hyper-v environment and I'm definitively not an expert) :

- 2 x 10K 146 GB SAS drives in mirror for Hyper-V Core (maybe for the price, why not 2 x Intel 520 SSD ?)
- 2 x 10K 146 GB SAS drives in mirror for SBS2011.VHD and maybe the 2008R2.VHD if I take the SBS2011 Premium licence (I would then add more RAM)
- 2 x 10K 146 GB SAS drives in mirror for Exchange database,
- 1 x 10K 146 SAS drive for the System Files (pagefile.sys) on a VHD drive (just read about this and I'm not to sure).

- 1 x 10K spare drive, not connected. Just in case.

I could use the integrated 420I Raid card, or maybe an Adaptec 6xxx Serie with SSD caching?

What do you think ? Do I really need the 2 x 10K sas drives for the Hyper-V Core ? A good Intel SSD would be sufficient for it ?

I'm really looking forward for your feedback !

Thank you
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Author

Commented:
Wow, many comments :D !

After checking around some prices, I have modified my configuration  :

- ML350 G6 (Xeon E5620 2.4 GHz, 30 Go DDR3)
- 2 x 60GB Raid 1 Intel 520 SSD for the Hyper V
- 2 x 180GB Raid 1 Intel 520 SSD for SBS2011
- 2 x 60GB Raid 1 Intel 520 SSD for Exchange
- 1 x 60GB Intel 520 SSD for Swap

After seeing the prices and that the MTBF of Intel SSD is 1.2MH when SAS 10K drives is 1.6MH, why not doing full SSD ?

Still looking forward for any comments :).
This looks fine, except I would use a Raid 5 for the SBS VM. The SBS itself will eat up 100 GB pretty quickly. A large RAID 5 partition or an additional partition for data will do you some good.
kevinhsiehNetwork Engineer

Commented:
I don't understand what you mean the data is going to be on NAS via iSCSI, and then talk about all of these internal hard drives.

I feel like you are taking an approach that is trying to work around limitations of traditional hard drive architecture, and then apply that to SSD which has different limitations. Why would you have all sorts of different RAID sets, instead of just 1 large RAID grouping? It makes little sense with spinning platters, because you don't allow all drives to contribute to the required IOPS (only 2 out of 7 drives in your original proposal would be able to support the IOPS needed for Exchange), and in the SSD configuration IOPS are not an issue, but you limit flexibility in capacity. My recommendation is to do a single large RAID 5 or 6 array on SSD. I would probably just have a single C partition on the host, so you don't tie up a huge amount of capacity for the host. Use dynamically expanding VHDs for your VMs.
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Author

Commented:
Thank you for your feedback, made me thinking :).

I don't like the time that is needed to rebuild a Raid 5. The point of doing an Hyper-V is that even in worst case scenarios, building a server back up would take less than an hour... If Exchange data and Swap is not on the SBS.VHD, 180GB is for sure enough. Why would I need more place ? I do agree that 60GB for Exchange DB is maybe a bit short.

The data, meaning our Office documents, pictures, user's profile, etc... will not be on the Server, but on a separate NAS.

Why all these different raids sets ? Well, I thought that responsiveness would be better, because the SSD would be all working in parallel. I used to do something like this with classic SAS disks, but maybe I'm all wrong, reason I'm looking for help :). The Hyper-V, once installed and configured, will not do anything, so putting it on the smallest SSD seemed to me logical, especially that is obviously not a vhd file. But for SBS, Exchange and the SWAP, are you two saying that it would really be better to have 3 x 180 GB = 360GB available on it, having 3 vhds : sbs2011, exchange and swap ? What about putting them all in one VHD ?

Finally, I read almost everywhere that is was preferred to use fixed VHD in SBS environment. No ?

I haven't yet really found out how should the Server Core be backed up, if it's necessary or not. That's why I did a mirror raid just for it. Other scenario possible ?
Network Engineer
Commented:
Rebuild times for SSD and spinning rust should be radically different. Having multiple RAID sets reduces parallel operations. If you have a pair of SSD for the host, that is thousands of IOPS unavailable to Exchange or the VMs. If you have all drives in a single RAID group, all drives can help provide IOPS for all operations, as well as add to throughput. In reality, the only reason to use more than 2 SSD drives is for capacity reasons, not IOPS. With spinning rust you need many drives for IOPS and possibly capacity (but with 3 TB drives, you probably can get enough capacity with just a mirrored pair). With SSD, a single pair of drives should give you plenty of IOPS, but probably not enough capacity, which is also why I recommend RAID 5 or 6 because it maximizes capacity and space flexibility, which is at a premium when using SSD.

I wouldn't put my Exchange databases on the C partition of a VM any more than I would on a physical box, for reasons that it is nice to be able to keep the data separate, and it is easier to backup/recover.

Performance differences between fixed and dynamic VHD have been virtually eliminated in Hyper-V 2008 R2.

You don't need to backup the host as much as you need to backup the VM and the contents of that VM, such as Exchange, and have the ability to do granular restore.

Author

Commented:
Thanks Kevinhsieh for your time, highly appreciated !

It does make sense what you are saying :) !

So, new configuration :

- 1 x 60 SSD for Hyper-V Core (once everything is configured, I make a copy of the SSD). Downside : if it crashes, everything is down and nothing can be done until the SSD is replaced with a copy. So for the price of a 2nd SSD, I would still consider 2 x 60GB SSD for the hyper-v

- 3 x 180 SSD for SBS2011, Exchange and Swap, configured in 3 dynamic sized VHD.

It's more or less the same price, but this is going to be much faster :). It is still worth to do a seperate VHD for "Swap" (pagefile.sys, temp folder, ...) ?
kevinhsiehNetwork Engineer
Commented:
You can use 7.2K SATA for Hyper-V host if you wish. If you choose to use SSD, I suggest that you might want to put the SWAP VHP for the VM on the host drives, only for space reasons.

Separate VHD for different functions is for management, not performance.

BTW, users in Outlook cached mode don't normally notice Exchange performance. Would it make sense to put some of the documents on SSD instead? Why not put Exchange in the cloud? Doing anti-spam, anti-malware, and backup/restore of Exchange is pretty expensive.

Author

Commented:
Of course I thought about 7.2K SATA disks ... but i don't have many choice's of HP Server with 3.5'' bays. For now, with my new configuration following your input, I'm spending around 1'150$ for SSDs. Putting 7.2K will indeed be cheaper, but we are talking about a few hundred of $. I have so little to stock this is the reason why I'm interested in SSD.

Very true for separate VHD files, it is really convenient for backups, managements, ...

Some of the documents ? Mmm I believe (for SMEs!) that it is a good reason to separate the documents from the server. I recommend Synology NAS and I think they are excellent. The speed read / write are way faster that gigabit lan and these NAS bring some interesting features (Cloud station, FTP, File station, iSCSI, backup for the server, easy access for Mac users, Time Machine backup, ...). And if the server crashes, we can at least work on our files...

I'm totally against having Exchange Online (you are talking about this no?) : the price is really not interesting, and having your own server, on the long term, is cheaper. A good antivirus / antispam + a backup program with individual pst backup and I'm set. And the licence of SBS is really cheap ...
kevinhsiehNetwork Engineer

Commented:
I agree that SBS is really cheap, but when you add on purchasing AV for Exchange, anti-spam, and backup software and hardware, it isn't so cheap. I help manage 600 users, and I can tell you that buying and keeping everything related to Exchange is really expensive and a PITA. The main reason why we keep it in house is that we have already purchased all of the backup hardware/software, AV software, anti-spam services, Exchange CALs, etc. Otherwise, going cloud would make a lot of sense.

There are also 2.5" SATA drives (laptop drives), but it looks like you would save maybe $100 over SSD.

Author

Commented:
I'm talking of 50-user per domain (SBS2011 is limited to 75), so for this kind of scenario, hosting your own Exchange (of course with the proper IT partner) is the best solution.

I would never put laptop SATA drives in a server.

Thank you Kevinhsieh for the time spent sharing your experience.

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