Available emergency storage on SAN

[misius]

I have a 6 TB SAN with 14 servers attached, and was wondering if anyone knows of a best practice for how much free space (percentage or quantity) should be left available for emergency use. Any references would be great.

Thanks

 

[comtec17]

What is your definition of emergency use and what would you use it for? I have just installed a 110 TB SAN Disk solution for a customer and they are using every possible byte of the disk. I do not see a need for an emergency space in a SAN environment unless you are not protected.

 

[misius]

To me, the emergency use is an admin comes to me and says they need 100 GB because they just ran out of disk space and the auditors have asked for a second copy of the database.

 

[comtec17]

If an auditor or customer asks for more space, in most worlds this is not an emergency. It sounds like you need more of a capacity planning issue. I would trend your storage back to 2 years ago and up to 3 years in the future so you will be able to see the possible growth that you will endure.

 

[liamfogarty]

It depends,
If your infrastructure is stable (i.e. not growing abnormally or adding new servers all of the time) then you should have minimal spare space (in your example <100GB)
But if your infrastructure is changing/growing then it is nice to have a 5% head room to allow for any 'emergency' work.
But try getting the buyers to buy that extra 5% just for emergencies? . .not much chance...