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Should we go no hard drive or with hard drive for a traditional 3-2-1 virtualization?

We will go for a traditional 3-2-1 virtualization project. Our vendor presented a diskless configuration -- no disk, no controller. The VMware ESXi will be embedded with image on two flash media. We have been thinking if "with hard drives" could be better than diskless since with raid hot-swappable hard drives you are able to replace hd once bad. Can you comment and shed some light please?
3 Solutions
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
We have been deploying ESXi embedded, this is what it's called, when using internal SD cards or USB flash drive, since 2004.

With no hard disks at all in the hosts, and all the volumes/datastores are presented from the SAN.

The media or disks are only used to BOOT the OS (ESXi) and then it goes memory resident.

We found, that disks, even in RAID mirrors would fail, just because they are spinning all the time, especially if you purchase the same disks, same batch, the other would fail, on Rebuild.

It's also easier to restore, and rebuild, you can have a spare USB stick, and just restore the configuration.
Carlos IjalbaSenior SysadminCommented:
Basically this is not as important in VMware ESXi environments, as usually you have a few hosts, and the important stuff (the VMs), are really hosted on SAN, so if a ESXi host dies, you can start the VMs in another ESXi host, meanwhile you fix the broken one.

That's why the best configurations on ESXi is with more than 2 hosts, and 1 host configurations are really not very flexible protectionwise.

Many ESXi hosts, have the OS in a 4GB USB pen and boot from there!

Once ESXi starts up, the whole OS is kept and executed in RAM, and the only accesses to disc are to write to the logs (which can be sent over to a remote syslog receiver, so you don't even need disk on the ESXi for the logs).

Others use SD cards for the OS instead of USB pens, so I would rather have a couple of SDs or USBs with the OS image than spend good RAID disks for this.

You can use this disks as JBOD for local datastores to keep OS ISOs, for example.
Sebastian TalmonSystem Engineer Datacenter SolutionsCommented:
+1 for the diskless Version

if esxi detects that it is running on flash media, it does not write logs to it (asks you to configure log directory on datastore or syslog target) - so there is practically no write i/o on the flash media

Also if you go with DELL server hardware, you have the choice for a config with redundant sd-cards
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