This post has been prompted by a couple of questions I’ve had recently from readers and people I know asking “Simon, it’s all very well showing us how to install VMware ESXi onto a USB memory stick though why would I really want to do this in the real world?”

As you probably know VMware ESXi can be run from either disk, USB memory stick, SD Card or from SAN with the latter still deemed ‘experimental’ at this stage.

The following are a couple of basic reasons why I’d choose to install and run VMware ESXi from a USB key or SD memory card as opposed to local disk.  I’m not saying that memory stick or SD card based ESXi installs are better than those on local disk because as with most things it all comes down to ‘what is the best fit’ on a case by case basis.

– No local disks on the ESX(i) host: Enterprise level servers such as the HP Proliant BL490c (Intel) or BL495c (AMD) are geared towards virtualization and so as to maximize physical memory space in the servers case it doesn’t come with internal disks. For these servers a hypervisor such as ESX(i) can either be booted from SAN (though this is only experimental at this stage for ESX(i)) or booted from a USB memory stick or SHDC memory card. That said, the only servers that tend to be diskless are blade servers. So if using rack mount or floor standing servers why bother you may ask…

- More space on local disk: By installing and running ESXi from a USB memory stick you have 100% of any local disk for ISO storage, or if not using shared disk space via a SAN or NAS appliance then you can use all or part of this local disk space to run your VMs from.  The actual footprint of an ESXi installation is actually quite small (ie: just under 1GB for ESX 4.0) leaving plenty of local disk space available so with the capacity of modern disks (eg: 74GB+ minimum) the space it consumes is something of a non-issue. This particular point of running ESXi from USB memory stick or SD card as opposed to local disk is a little hard to argue though for me personally I like the flexibility in my lab environment of keeping my ESXi install and any local disk storage used for ISO’s or VMs separate. This means I can easily pull out one USB memory stick containing a version of ESXi and insert another containing a different version within seconds without impacting any ISOs files or VMs. To do this with a disk based ESXi install is much more hassle.

- Remote Site Deployment: If you are sending a server to a remote site direct from a supplier or manufacturer then it is easy to post/courier out a pre-configured USB memory stick containing ESXi complete with the ESXi configuration all set up and have someone with little or no IT skills plug it into the server to get things up and running. This combined with sending out pre-installed and configured VMs on a portable USB hard disk to the remote site, to be copied onto and run from the local disk of the ESXi host or shared storage, makes an administrators life much easier than trying to perform an install and configuration using virtual media over a limited network connection using an ILO, ILOM or DRAC.

There have been some interesting discussions going on regarding memory stick and SD based hypervisor based installations which can be found on these good posts here – well worth a read:

VMware ESXi 4: SD Flash in BL460c G6 – VCritical (Eric Gray) Note: Check out the photo of the new SD Slot located on the side of the BL460c – a nice feature in my opinion.

Blade Servers with SD Slots for Virtualization – Blades Made Simple (Kevin Houston)

A significant point of interest as mentioned in Kevin’s post is around HP’s u-turn in running ESXi from their own 4 GB USB Flash Media Key (Part Number 580385-B21) on the following popular servers in their Proliant range:

• ProLiant DL380 G6 server
• ProLiant DL385 G5p server
• ProLiant DL385 G6 server
• ProLiant BL460c G6 server
• ProLiant BL465c G5 and G6 server

The reason given in this customer advisory is due to a “potential for erratic system” with the USB memory stick/key being in “close proximity to other components”.

When visiting the HP Proliant campus over in Houston in 2008 an engineer who was part of the Proliant DL380 G6’s design team informed that they had a number of instances of factory installed DL3xx’s with the ESXi memory stick where the memory stick would fall out of its internal USB port during transit from the factory to the client site.  This being part of the reason why they moved to an SD card slot located on the main system board.

So these are my reasons for installing ESXi onto a USB memory stick or SD card.  Why not let us know of any other reasons you can think of for installing ESXi on a USB memory stick or SD card as opposed to local disk – it’d be good to hear your thoughts and/or experiences.

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