How to Tag/Enable a device as SSD in ESXi.

ESXi 5.0 supports SSD disk. What does it mean?
You  might already rememeber some hints on SSD support prediction in the past on this blog.Yes, ESX now officially support SSD disks.With this support user now can plugin SSD into ESX ( vsphere5.0 onwards), and configure ESX to use the same for caching or storing VM swap files.To utilize the SSD disk for holding caching purpose , you need to create a datastore on the device and then you can select the %-age space to use it for esxi caching from 1-100%. You can observe the ESXi performance better then its predecessor.

That said here is the catch.Some times even though the disk is SSD ESXi can not recognize the disk as SSD. There is a reason for that, if the disk attached to raid controller , few raid controllers donot  give ESX  the access to the mode page ,to determine whether the device behind the RAID is  SSD or not. In such cases where device does not show up as SSD we have a provision  to Tag/Enable the disk as SSD. We can as certain claimrules in ESX for the disk which we are sure to be a SSD. You can also mark a magetic disk as SSD using this method for testing.

This can be done using the PSA claim rules,

#  esxcli nmp satp addrule --satp VMW_SATP_ALUA_CX -t vendor -V DGC -M "RAID 0" --option="enable_ssd"

--satp = SATP which claims the device  
Note: you can get the device satp by 
"esxcli storage nmp device list"
vendor -- vendor of the device
model  -- Model of the device
Instead of using vendor/model there are different options available in esxi 5.x to add SATP Claimrules.
You can use device,transport....etc.

Support for SSD on ESX4.0 and ESX4.1

With lot of enterprise SSDs in the market today, one question in the storage admins mind  is,

what performance benefits do I get, if I connect SSDs to my ESX servers.

Sadly ESX40 and ESX4.1 do not distinguish between a LUN  backed by SATA disks or SSD.Hence when SSD backed LUNs are presented to ESX server, ESX makes no effort to either use the high performace SSD disks or communicate the information to VC that, the LUNs which are presented by array are actually backed by SSDs.

Presence of SSD can essential help servers in many ways.

ESX can use the SSDs to store VM related information like swap files.This will essential improve VM performance. Other uses can be improve the boot time of  ESX.

With SSD support from ESX, usecases in virtualized environment are immense. Its just matter of time before everyone would see what VMware has to offer around SSDs.