Advice on Server for hosting test VMs

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Atlanta55

65 posts

Master Geek

#150518 25-Jul-2014 11:50

Hey there,
Looking for some advice regarding virtualization please. Not something I've had to think about before :)

Need to build a new server to host some VMs for use by our testers.

Currently using Hyper-V on a fairly standard i7 workstation and its performance sucks. Its running 8 Windows 7/8.1/2008/7em VMs, with usually only 3 or 4 of them in use at any one time. Its got 32Gb of RAM and a decent i7 but I can see the choke point is disk response time, its terrible and causing all the VMs to crawl along.

Thinking about replacing it with a HP Proliant DL 320 or DL380, but wondering about what specs it really needs.

For say 8 VMs running at once, giving them 4Gb of RAM each and at least two CPU cores, what kind of CPU or CPUs should I be buying? Xeons any better then i7s?

I obviously want a decent RAID controller, any recommendations here on a real fast one to help reduce any disk access issues?

Is it worth going for one that can support RAID5 instead of RAID1?

and finally, in my own experience I've never seen anyone use Hyper-V outside of Microsoft training courses, VMware seems to be the industry standard. Are we wasting our time with Hyper-V as its reported to be slower then VMware? Should we bite the bullet and switch to VMware for better performance?

Cheers!

Zeon

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#1095526 25-Jul-2014 11:58

Your BIGGEST issue is disk access with virtualisation. RAM is just a bit of planning and CPU can almost be an entire afterthought altogether. You could probably just add a high performance RAID card to your current config. Choose something with a battery or flash write back (as big as possible) as this will make a major improvement.

I'm quite a fan of LSI gear and in fact IBM etc. actually license their chips for their own cards. This is probably a model to aim for:
http://www.lsi.com/products/raid-controllers/pages/megaraid-sas-9361-4i.aspx#tab/tab2

Make sure to get the optional cache vault module which will give you write back. You will also need 2x ENTERPRISE storage drives. Make sure the drives you choose are on the list of supported drives for that card. I can't stress that enough.

It's going to be expensive. Perhaps you could look at just a large SSD instead...? Still probably won't be as fast without write back cache but could be a more pragmatic price?

Speedtest 2019-10-14

Dynamic

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#1095556 25-Jul-2014 12:41

Consider just throwing one or two large SSDs at it just using AHCI.

Unless you need real-world performance in which case throw at it one of the RAID cards you will be using in the production servers. You can then potentially use cheap 3rd party disks and/or SSDs in the test environment behind that RAID card to approximate the performance of the production servers.

VMware used to be notably quicker but I think HyperV has caught up. I believe VMware's management tools are more mature.

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toyonut

1508 posts

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#1095559 25-Jul-2014 12:49

What OS is the workstation running?
We run a couple of DL380's at work with dual CPU's and 96GB of RAM in each. They have the primary disk bay full of disks in a couple of RAID's. Never had any performance issues and run much larger loads than you are looking at.
If you want to spend the money they are a great way to go. You can pull all the disks out of a raid group, put them back in in a different order and the server will pick them all back up again.

I would ring up an HP dealer and talk it through with them, but I would probably look at a DL380 with two entry level xeon CPU's, 40GB of RAM and a bunch of disks. If you go with the 380, there will also be a lot of room to grow where the 320 is pretty much the same as your current system just with better disk access and would be tapped out running that load.
Spread the disks out into a couple of good RAID's, set up the network with one NIC port for host management and another for the VM virtual switch, don't share network access if you don't have to.

If you don't want to spend up for a big server, add more disks and a raid card to your current pc and add a second good quality PCI-e gigabit NIC. Use the onboard NIC for management and the second PCI-e NIC for the VM switch. Don't share it with management. We have used Intel PCI-e server NIC's and RAID cards in other systems at work and I have found them excellent.

*Edit* Second the above, Hyper-V will be just as fast as VM-Ware especially as you are running modern Microsoft OS's.

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mrdrifter

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#1095602 25-Jul-2014 13:43

You may be looking for something similar to what we use for our development and testing. Although we are running mostly Server OS we also have a few client OS machines running, our machines get cycled quite frequently as we trash and re-build regularly.

Xeon E5-2620 v2 (with upgraded cooler)
64GB RAM
Gigabyte Motherboard
Dual Ethernet (quite important with high simultaneous connections)
250GB System SSD
3 x 250 VM SSD
1 x 750GB VM SSD
1 x 1TB Sata 3 Drive

All SSDs are Samsung EVO Series.
(All backed up to a NAS)

I currently have 8 machines running at 90% memory utilization with one dedicated SQL box and six self contained SharePoint Dev boxes using 4-16GB each. We have had no slow downs and its really about ensuring the VM's have memory prioritisation managed correctly and are spread across the SSDs based on load requirements. Reboot of a VM takes about 5 seconds on average.

We built our machine from scratch to meet our specific requirements and I think the total cost came in around $5000. Many would argue that its all consumer gear, but you need to look at your true requirements for a Dev/Test host and the cost/benefits. We work in a very small office and the box runs almost completely silent.

JWR

821 posts

Ultimate Geek

#1095618 25-Jul-2014 13:51

The single biggest difference you could make is using SSDs over hard disks. SSDs support a lot more I/O operations and have much faster access times. Just what you need for VMs.

After that, it might be worth going to fancy RAID controllers etc.

If you are considering RAID 5 then you really do need a decent battery-backed controller. However, in a test environment you probably wouldn't need RAID 5.

Xeons are usually better than i7s- at a cost.

You can get more cores, more CPU cache and easier to find multi-CPU systems/motherboards. Also, Xeons may have extra CPU instructions/features to support visualization (depends on the model/generation).

I think VMware and Hyper-V are pretty similar in performance these days. They both support ridiculous amounts of RAM, disk space and CPU cores.

Hyper-V works pretty well in a Windows only environment.

Dynamic

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#1095622 25-Jul-2014 13:58

We now stick with the Intel S3500 series SSDs for servers for this reason: http://beta.slashdot.org/story/196131 .

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JWR

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Ultimate Geek

#1095647 25-Jul-2014 14:31

Dynamic: We now stick with the Intel S3500 series SSDs for servers for this reason: http://beta.slashdot.org/story/196131 .

If you look below the text there is a link to SSD failure vs hard disk... http://hardware-beta.slashdot.org/story/13/09/12/2228217/ssd-annual-failure-rates-around-15-hdds-about-5

(SSD Annual Failure Rates Around 1.5%, HDDs About 5%)

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Atlanta55

65 posts

Master Geek

#1095649 25-Jul-2014 14:31

Excellent replies everyone, thanks very much!

To be honest the testing time we are wasting by waiting for VMs to build is costing us money so I don't mind throwing a few grand at the solution. I think I want a long term server solution that will last us a good few years, rather then updating the current workstation with SSDs, so I think I'l get HP to spec us a DL380 with 2x enterprise drives raided.

The host machine is running Server 2012 and Hyper-V. Is this a bad choice too for a host OS?

The test guys often snapshot a clean build then restore that when they've trashed it too much, is snapshotting like this also decreasing performance perhaps?

timmmay

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#1095653 25-Jul-2014 14:38

RAID'd spinning disks, even high end ones, will still be significantly slower than a single SSD. I think SSD is really important. Samsung 840 pro are very reliable, though there may be an 850 out now or soon. RAID is really for reliability and uptime, not performance. If you need both performance and reliability get a couple of Samsung 840 SSDs. They're basically $1/GB, the same price standard disks were 5 years ago (or 10, I forget). Link to PB Tech.

Xeon are more reliable and maybe a touch faster, but not much. RAM is important too, sounds like you're not doing too bad for that.

JWR

821 posts

Ultimate Geek

#1095656 25-Jul-2014 14:45

Atlanta55: Excellent replies everyone, thanks very much!

To be honest the testing time we are wasting by waiting for VMs to build is costing us money so I don't mind throwing a few grand at the solution. I think I want a long term server solution that will last us a good few years, rather then updating the current workstation with SSDs, so I think I'l get HP to spec us a DL380 with 2x enterprise drives raided.

The host machine is running Server 2012 and Hyper-V. Is this a bad choice too for a host OS?

The test guys often snapshot a clean build then restore that when they've trashed it too much, is snapshotting like this also decreasing performance perhaps?

Server 2012 is fine. It has a few Hyper-V improvements over 2008R2. Server 2012R2 has a few more improvements.

Snapshots do decrease performance. But, of course snapshots are a feature that is intended to be mainly used in a test environment.

Atlanta55

65 posts

Master Geek

#1095673 25-Jul-2014 15:09

timmmay: RAID'd spinning disks, even high end ones, will still be significantly slower than a single SSD. I think SSD is really important. Samsung 840 pro are very reliable, though there may be an 850 out now or soon. RAID is really for reliability and uptime, not performance. If you need both performance and reliability get a couple of Samsung 840 SSDs. They're basically $1/GB, the same price standard disks were 5 years ago (or 10, I forget). Link to PB Tech.

Xeon are more reliable and maybe a touch faster, but not much. RAM is important too, sounds like you're not doing too bad for that.

OK thanks I'll take your advice on that. I did Compaq server training over 10 years ago so always had RAID stuck in my head as the fastest solution, but those days are over. Reliability isnt too important for the test team, our critical office data is on a differnet server that does have lots of RAID redundancy and cloud backup.

Cheers

timmmay

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#1095680 25-Jul-2014 15:23

Ok, then one fast SSD in your current PC is probably going to make a pretty big difference and meet your needs. A server in a rack is probably better than a PC on a desk, but performance wise pretty similar I guess.

JWR

821 posts

Ultimate Geek

#1095805 25-Jul-2014 18:38

JWR:
Atlanta55: .......

The host machine is running Server 2012 and Hyper-V. Is this a bad choice too for a host OS?

The test guys often snapshot a clean build then restore that when they've trashed it too much, is snapshotting like this also decreasing performance perhaps?

Server 2012 is fine. It has a few Hyper-V improvements over 2008R2. Server 2012R2 has a few more improvements.

Snapshots do decrease performance. But, of course snapshots are a feature that is intended to be mainly used in a test environment.

I was in a bit of a hurry earlier... so forgot to add..

By default Hyper-V stores all it's snapshots in the same directory. Its even in the same directory tree as your default machine definitions and .VHDs.

However, you can change the snapshot directory for each VM. Its under settings, near the bottom of the list.

It might speed things up a bit if you move some of the snapshots to less busy disks.

Benoire

2799 posts

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#1095821 25-Jul-2014 19:22

I use Xenserver 6.2 on an AMD whitebox. I have 3 Server 2012 R2 vms, a windows 8.1vm and a windows 7 vm. My main bottlenecks are RAM and HDDs. The CPU is an AMD fx-6100 and is hardly above 5-10% load at all times doing what I do with it... Ram I'm always running out of and HDDs are slow.

I'd invest in SSDs or raid arrays as appropriate and more ram... The i7 should be fast enough.