Local Storage for ESXi - USB SD or Traditional Hard Drive

[etieseler]

We are going to be replacing our ESX hosts soon with new hardware and I am on the fence about using a 4Gb USB SD drive or traditional hard drives in a RAID. Obviously the SD drive has its benifits, namely its speed and reliability, but is it reliable enough to forego using redundant hard drives?

As someone mentioned before, we spend so much of our time concerned with making our hard drives redundant fully expecting them to fail. Many times the failure is related to the moving parts in the drive also. SD drives have the enjoyment of having no moving parts to wear out or fail. But how reliable are they?

The reseller I spoke with has been selling them for 3 years and never heard of a failure. Its $62 for 4 Gb, so its not a bottom of the line edition. It is designed to be in an HP DL380G7, so again, I doubt its a lower end model.

I am leaning towards the SD drive rather than the traditional drives, but I wanted to get input from others that may have used this setup before. I am looking for success stories and failures (and the reason behind the failure).

4Gb is enough for the install (ESXi 4.1) and I do not need any further local storage as VM's are on shared storage, and the helper VM's such as AppSpeed and esXpress I can also install on the shared storage (Where in our current datacenter these are installed on local storage). Or should I be concerned about this size in regards to logging or anything else?

Thanks in advance, please discuss.

Eduard Tieseler

[petedr]

I have not tried it myself that but I found this article comparing using USB drives for installing ESXi or stardand scsi drives.

http://searchvmware.techtarget.com/tip/Loading-ESXi-Installable-on-a-USB-drive-The-requirements

[idle-jam]

we did alot of USB and it's all good. after all the heavy part would be where the VM is seated and there is why much of the IOs are needed.

[AureusStone]

I prefer USB/SD.

When the host boots it copies the Hypervisor to memory.  As a result if your SD card has issues, your host will keep running until you reboot.  And then you can just put a new SD card in and reconfigure.

The amount of writes to the SD card isn't a problem, as wear leveling will distribute the wear across the entire 4GB.

[WiscBrad2011101]

You raised a concern about logs. You can configure logs from your host to be send to an external location like a network share. 

[Dave_Mishchenko]

Some newer servers are starting to offer mirrored flash devices.  Dell has a couple such models.  I'm not sure what IBM / HP offer at this point.  

A local RAID array is pretty much wasted if you just use it for an ESXi install as the I/O needs are minimal.  If you do go with a flash device remember to set a scratch partition and to configure syslog to dump a copy of the vmkernel log file to a datastore.

[bulletprooffool · Accepted solution]

I've had a bout 100 ESX hosts running from USB - the only issues I ever had were with the original green USB keys that HP provided in the early days of ESXi on USB.

I like the USB approach for multiple reasons -

1. No local physical disk required, fewer moving parts = fewer hardware issues

2. If you do have local physical disks, you can use these as dumping grounds for ISOs etc.

3. If I rebuild a server, I can remove the old USB key and build on a new one - and recover simply by replacing the OLD USB key

4. I can pre-build a USB key an duplicate it as a method of building servers in bulk (not tested on 4.1u1 though)

5. I have had many many hard disk failures . . USB (other than the green HP ones) have never failed on me.

also, your syslog issue is not treally an issue 0- best practice is to get servers to log to a centralised syslog box anyway (I'd do this even if I was not using USB/SD)

Good luck - let us know what you decide.

[petedr]

Thanks for the helpful

[etieseler]

Thanks to everyone for the input, it looks like overwhelming support for a flash style driver vs traditional hard drives.

That is what I was leaning towards from the beginning but wanted to get others experiences and do some research on my own about the reliability of these flash drives.

To answer what we decide to use, we will be using the Flash USB drive. If I remember to post a follow up after we are live on our new servers I will post an update as to how it went and if we run into any caveats or things to be concerned about.

Again, thank you to everyone for your input!

Regards,

Eduard Tieseler