Installing Xen or VMWare on separate storage device

I'm building a server which will be running XenServer or VMWare ESXi, and it will be using local storage in a RAID10 array running off an LSI MegaRAID card for storing the VMs.

In the past, when I've asked for quotes on this sort of thing I've been given Dell servers with 2x 146GB 15K SAS disks, or 2x SSDs in a RAID1 for the actual installation of Xen or VMWare, and then 4x 10K SAS disks for the storage of the VMs.

Is there a specific reason why the installation of the hypervisor should be installed on separate local storage than the VMs datastore?
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Usually it's to give the flexibility of adding/removing datastore storage as required, which is not an option when the OS is stored on the datastore you want to remove.

These days it's recommended to install the hyper-visor on either an SD card or USB flash drive. A lot of servers now come built in with an internal SD reader or USB port for this purpose. Not only is it a lot cheaper to do so, but it's quite easy to clone the SD card or USB flash drive to have redundant copies.

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Paul SolovyovskySenior IT AdvisorCommented:
With ESXi hosts we prefer to use the 4GB SD cards and the slots are available in most servers.  This keeps the datastore separate from the install, and keep in mind that when ESXi installs is essentially memory resident where you could even remove the hard drive it's running on and it will run properly until reboot
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
If using VMware, install ESXi onto a good quality USB flash drive or SD card, e.g. HP, SanDisk, Kingston. We've been installing ESXi onto USB flash drives since 2004, with no issues.

Some Dell servers have internal USB slots already, or you can purchase an SD card reader seperately.

ESXi only requires a 1GB footprint for the installation, however, Xen does require a larger footprint to install.

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

You can then also easily backup the entire SD card/USB flash card if required. See my EE Article

How to Backup an ESXi installation on an USB Flash Drive or SD card, for security or redundancy.
Frosty555Author Commented:
What is your opinion of installing Xen or VMWare onto a single SSD, instead of a USB stick?

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
for Xen, probably okay to install on SSD, Xen based USB Flash drive boots take a while to boot, because of it's large footprint.

for VMware ESXi, which has a small 1GB footprint, a total waste of money.
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