EVA5000 general performance question

[Lacrosse]

In general terms on a EVA5000 with
104 - 72.8 GB (15K) drives. 10 shelves
2.5TB used in RAID 1 and 450GB in RAID 5
and 7.5TB RAW
Are there any general guidlines to how much free space should be kept for best performance or does it depend purely on the amount of data being pushed

Thanks for the help!

[Mark Poeschl_2 · Accepted solution]

If your capacity requirements are fairly stable, then the amount of free space (at the controller level) isn't going to have much effect on performance. It will however, have an effect on the amount of time it takes to re-level or reallocate space should you add drives or re-allocate drives amongst disk groups. Controller-level free space will also have an effect on snapshot/snapclone performance.

Free space at the OS level on the other hand can affect performance in that more free space will make it easier for the OS to keep fragmentation low and thus file access "easier."

[Ivan Ferreira]

Also remember that free space is used first when a disk fails. If there is no enough disk space to reconstruct the data, the spare space (protection level of the disk group) is used. So, having enough free space won't hurt.