Recommended free space on EVA4400

[noodles]

Hi,

we have a EVA4400 with one Diskgroup and two vDisks.

When creating a new vDisk the system shows me how much capacity is free.

Is there a statement how much free space there should be left on a EVA or can I can consume every single byte?

Thanks in advance.

regards

[Víctor Cespón · Accepted solution]

Minimum to allow leveling and rebuild is 5 GB, but you should leave more than that.

In the disk group properties there's a parameter called Disk failure protection. Single reserves the space equivalent to 2 x (biggest disk on disk group), and that space is reserved to be able to rebuild in case a disk fail.

Having too little disk space free means that when a disk fails, the rebuilding process will not be possible until you physically replace the failed disk.

With 450 GB FC disks and 1 TB FATA disks, you need a lot of space to rebuild.

[Amar_Joshi]

Best practice recommendations are to keep the utilization below 90% in the diskgroup.

Simple to understand is that per 8 disks you should spare one disk equal space. E.g. if you have 24 disks (450GB each) then you should atleast leave ~1.5TB space unused in that diskgroup.

As mentioned, this space is breathing space for the diskgroup that will serve the disk group in the events of releveling, disk-failure and rebuildings.

Hope that helps.