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Microservers Instead of Virtualization? Page 3

By Jeffrey Layton (Send Email)
Posted February 11, 2013

Microservers Instead of Virtualization?

Microservers sound rather cute, don't they? It's a small server with some limited capability relative to a full server, but a microserver also uses a great deal less power. Given that many servers are only about 15% utilized, this brings up a question.

Could very low-power microservers be used instead of virtualizing a much larger server? Rather than taking under-utilized servers and putting them in a VM along with lots of other VMs on a larger server, couldn't you just put the application(s) from the under-utilized server on its own micro-server?

Let's do a quick comparison between a cluster of micro-servers and a virtualized server. Let's assume that a single core on a larger server is the equivalent to maybe 8 microservers. In the case of a dual-socket Intel Xeon server you can get the equivalent of 128 micro-servers in terms of performance (8 * 16 cores = 128).

If we assume a microserver has 4GB of memory and a single hard drive (300GB, 10K, 2.5" drive) for local space, this means we need to have a virtualized server with 640GB (128 * 4GB = 512GB) and 128 drives (or equivalent). Moreover, we need to have a server with at least 12x 10GigE ports (128 * 1Gbps = 128 Gbps ~= 12x 10GigE ports). In summary we need a virtualized server with the following characteristics:

  • 16 Xeon cores (2x 8-core processors)
  • 512GB memory
  • 128 drives
  • 12x 10GigE ports (128 Gbps)
  • 128 VMs

This is quite a bit of hardware in a single server.

To better flesh out the virtualized server, I used on-line configuration tools for pricing and power usage. In particular, I used Dell for the configuration and the power measurements. The configuration I used is the following:

  • Dell PowerEdge R720with:
    • 2x Intel E5-2650 processors (8 cores each)
    • 24x 32GB 1333 MHz LRDIMMs (total of 768GB of memory)
    • PERC H710P RAID card in RAID-1
    • 2x 300GB, 10K SAS, 2.5" drives (holding OS and hypervisor)
    • Broadcom 57800 2x10Gb DA/SFP+ + 2x1Gb BT Network Daughter card
    • 5x Broadcom 57810 DP DA/SFP+ Adapter
    • PERC H810 external RAID card
  • Five Dell PowerVault MD1220JBOD. Total of 120 drives
    • 24x 300GB, 10K SAS 2.5" drives per chassis

This configuration has a total of 16 cores (128 equivalent microserver cores), 768GB of memory (about 6GB per microserver instead of 4GB), 120 disks (instead of 128), and 12x 10GigE ports total. From the Dell on-line pricing tool the price is $98,000, which I assume is the list price, and takes up about 14U of rack space.

Then I used the Dell Energy Smart Solution Advisor (ESSA) to estimate the power used for the entire configuration when fully loaded (which should be the case since we're virtualizing the server). The configuration used a total of 2,223.5W under load.

On the microserver side of the equation let's use the Dell Copper system for comparison. With Copper there are 48 servers per 3U chassis, and each server is a quad-core ARM processor with up to 8GB of memory (let's assume 4GB), a single 2.5" drive and a single GigE port. A total of three chassis will be needed, but the third one only needs 8 sleds (instead of the maximum of 12). Therefore this takes up 9U of space and uses a total of 2,000W almost exactly.

For pricing, let's use the list pricing for HP's Moonshot configuration, which was about $750/server. For 128 servers this is a total of $96,000.

Table 1 below compares the virtualized large server to the equivalent number of microservers.

MetricVirtualized ServerMicroserver (ARM processor)
Total number of servers 16 (128VMs) 128 equivalent
Memory per server/VM ~4-5GB per VM 4GB per server
Number of Drives per VM/server ~1 (300GB, 10K, 2.5") 1 (300GB, 10K, 2.5")
Network throughput per VM/server ~1 Gbps 1 Gbps
Price per VM/server $765 per VM ($98,000/128) $750 per server
Power per VM/server 17.37W per VM (2,223.5W / 128) 15W per server
Total used rack space 12U ~9U (third chassis is only 67% full)
Total Price $98,000 $96,000
Total power 2,223.5 W 2,000 W

The table is very interesting because the two options are so close in most areas. The microserver is about 10% cheaper and uses abut 10% less power, but this is likely within the margin of error for the comparison. However, the microserver option is more dense than the virtualized server option (about 50% more dense in this specific case).

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