This quick post will show how to add a disk to your array and convert your Raid0 disk to a Raid1 configuration without bringing your ESXi host offline.
This chap has all the commands listed on his blog which are worth checking.
This has been tested and implemented on a Proliant BL460C Gen9 and went without any issue, you have to check the commands below if you are using a different HP Hardware and/or consult your hardware provider about similar commands if you are using a different hardware build.
Change a directory to /opt/hp/hpssacli/bin
We will start by checking that the status of your Array is healthy by running
./hpssacli ctrl all show status
Check again the status of your Slot using
./hpssacli ctrl slot=0 logicaldrive all show status
This command will show you the drives you have on your controller and the Raid Level used (Fault Tolerance)
./hpssacli ctrl slot=0 logicaldrive all show details
We added a disk to the blade and run the command. /hpssacli ctrl all show config which now shows me that I have an unassigned disk
./hpssacli ctrl slot=0 modify rebuildpriority=high to start the job as a priority
Running ./hpssacli ctrl slot=0 Id 1 add drives=allunassigned will assign the drive to the slot you are about to work with and you need to know that the cache will be disabled during the rebuild
Disk 2 is now added to the Raid0 which will be converted to a Raid1 once the rebuild is done
Running this ./hpssacli ctrl slot=0 id 1 modify raid=1 will modify the Raid0 into 1 which believe me it took around 5 Hours to convert a 1.TB Raid0 to Raid1