Free space on physical disk with VHD drive – best practice.

PiotrIr

Just wander if somebody could help me to find answer for question about free space on physical drive (in production environment) which I need to have.

Scenario is as follow:

* One phisical server (no cluster)
* SQL Server on Hyper-V Windows 2012 Virtual Machine
* Fixed System VHD on 7.2 K SAS RAID 10 shared with other virtual servers physical Volume
* Fixed Database VHD on dedicated RAID 1 600 GB SAS 10K Volume
* Fixed Logs VHD on dedicated 300 GB RAID 1 SAS 10K Volume
* Hyper-V remote replication to DR site
* Altaro backup of Hyper Machines

Questions:

Can I use whole available space on dedicated volumes for Database and Logs? (600GB and 300GB) or do I need leave some space free? If so, could you advise how much?
Any advice about possible problems with following configuration?
Tank you

phatrik

My answer is more in the general sense than about your specific situation:

- A volume containing an OS should *always* have some free space. There's no hard rules, I like to have >10% of free disk space
- A data volume (i.e.: one used to store logs or DB tables) which doesn't also contain the OS could be filled to 100%, but why would you? What if the volume is filled at 100% and your application needs to write additional data to it? The application would crash and you'd have downtime. So to conclude, generally speaking, you never want a volume to have 100% of all its space used. Anything that has 75% utilization usually gets my attention and 90% is what I would consider a critical point (i.e.: I don't want my systems to have any less than 10% of free disk space).



HTH