Replacing traditional server HDs with SSD for gaining in DB performance?


I've got two virtual Windows Server 2008 32bit running on VMWare ESXi 4.0 on the RAID1 partition of a HP ProLiant DL360 G5. One of the virtual servers is used as a PostgreSQL database server. A colleague of mine is now trying to boost the read-performance of the DB and suggested to use (consumer) solid state disks ... but I'm a bit skeptical. So what is your advice?

Does this make sense? And what exactly would I have to do?
- backup my virtual machines
- replace the two disks
- create a new RAID1
- reinstall VMWare ESXi
- restore the virtual machines
- start and everything will be fine?


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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
RAID1 for a datastore will give you poor performance, because you do not have many IOPS.

You also do not mention what type of disks you have? SAS or SATA.

I would leave the RAID1 disks in place, I would then install ESXi onto a USB flash drive. 2GB USB flash drive is supported internally on the G5.

Here is the VMware KB on installing 4.1 on USB/SD:

Here is the VMware KB on installing 5.0 on USB/SD:

Install Consumer SSDs, Boot ESXi 4.1, and move the existing Virtual Machines from old datastore (RAID 1) to newer SSD datastore.

At this time you may want to consider ESXi 5.0, because it's SSD aware, and you can also use some space on the SSD for Host Cache Configuration to help Machine Swapping, under extreme memory pressure.

Copy your VMs from one datastore to the new datastore as per my article

HOW TO: Clone or Copy a virtual machine in VMware vSphere Hypervisor ESX/ESXi 4.x or ESXi 5.0

As for Consumer SSDs, we use them in ESXi, we use OCZ, Corsair and Kingston.

IOPS, Latency is far better, and your performance will be better as well.

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XeronimoAuthor Commented:

Ok, thanks so far! I'll check those out.

And so I can install ESXi on a simple USB stick, plug it into the USB port and then boot the server from it? Didn't know that was possible (and recommended) with servers?

On a side note: what RAID would you use on datastores then? I've got RAID5 on my other data stores. But in the case of the ProLiant, the datastore is the two internal SAS drives.

As for ESXi 5, I've got to check with our budget ...
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
RAID 10.

As for RAID with SSDs, personally I would not bother, just make sure you have good backups.

SSDs die!
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
We've been deploying ESXi on USB since 2004, yes it's supported, and that's why the G5 has an internal USB port for this purpose of Embedded ESXi!
andyalderSaggar maker's framemakerCommented:
So long as you get a USB stick that it atually boots from :(

As far as consumer grade SSDs are concerned you can use them but the fans may go on full speed if they do not have thermal sensors. For read speed RAID 5 or RAID 10 are both good, RAID 5 isn't good for write speed but I take it that that is not important here.
XeronimoAuthor Commented:
Little update/correction here: the current configuration is 4 SAS 10k disks as RAID5 in the ProLiant.

@hanccocka: Sorry for being a bit slow here but so you would do it like this:
- install ESXi on a USB stick for the internal USB port of the ProLiant
- replace the 4 internal SAS disks with 4 SSDs (do I need a new controller or something for this?)
- leave the SSDs as RAID0 and define them as datastore
- restore the virtual machines back on that datastore

- so which USB sticks will boot and which won't?
- the fans going full speed would not be ideal ... which SSDs would you recommend then?
- and you would, unlike hanc, use RAID on the SSDs?

Thank you
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
use 2GB SanDisks sticks

your method is correct.

do you really need 4 SSDs?
XeronimoAuthor Commented:
Another update: I just noticed that we recently got new a vSphere5 licence, good! :)
XeronimoAuthor Commented:

Ok, I will get such sticks then!

Uh, you're right ... maybe I don't need 4 disks if I won't use them as RAID in the first place ... But so can I simply use them inside of the ProLiant instead of the SAS disks? I guess I need special cases to connect them? Which ones would that be ... I'm obviously not really a hardware guy ;)

But so in that case I would then:
- backup the virtual machines
- power the server down, take out all the SAS disks, insert one or two SSDs
- install vSphere5 on a USB stick, stick it in the ProLiant and boot from it
- define a new datastore based on the SSDs
- restore the VMs, start them.

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
no real need to remove SAS disks.

you will be able to use as long as you get the mechanics correct.
XeronimoAuthor Commented:

But if I don't remove them SAS disks where will I connect the SSDs ... ?
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
in the chassis, you have eight slots?
XeronimoAuthor Commented:

No, only 4 slots! It's a ProLiant 360 G5. Although the HP website indicates 6 for the G5 (our server is in a different building) ... have to check that again. But in that case I could indeed simply add two SSDs ... yet I'm quite sure there are only 4 slots ...

But in that case I could simply replace them, right?
XeronimoAuthor Commented:
@andy: thanks, and those also work with SSDs? I only see SCSI or SATA disks mentioned on that site ...
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
XeronimoAuthor Commented:
Uh, ok ... stupid question then ;)

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