SSDs have become quite affordable, so I am now running my ESX with an SSD hardware RAID10.
Rocket! Rocket! What a joy!
The SSDs are set up via BIOS at the SAS/SATA controller when the machine boots.
In my case it is an LSI OEM controller available at reasonable prices on eBay: DELL PERC H310.
It supports RAID 0, 1, 5, and 10. I chose RAID 10 with 4 SSDs.
Now we need to tell ESX that these are SSDs. To do this, connect via SSH to the ESX.
Run:
esxcli storage core device list
to display the device list.
My controller shows up like this:
...
naa.6b8ca3a0f291db00237d714d0a6af726
Display Name: Local DELL Disk (naa.6b8ca3a0f291db00237d714d0a6af726)
Has Settable Display Name: true
Size: 1906688
Device Type: Direct-Access
Multipath Plugin: NMP
Devfs Path: /vmfs/devices/disks/naa.6b8ca3a0f291db00237d714d0a6af726
Vendor: DELL
Model: PERC H310
...
Then run:
esxcli storage nmp satp rule add --satp=VMW_SATP_LOCAL --device <device> --option "enable_ssd"
where <device> in my case is naa.6b8ca3a0f291db00237d714d0a6af726.
Now reboot the ESX!
Source: KB2013188