Hello Magnus,   Presuming that the units have identical type drives AND that the other array is reset, yes you could swap out the drives.   If the other array is configured, the RAID information on the drive will confuse the production array into thinking there's a LUN that's faulted.  So it won't work as a spare.  Regards, 
Hello We have a EqualLogic PS4000 SAN for our Veeam backups and the warranty has ended. My problem is that a disk has faild and needs to be replaced. The thing is, we have a "spare" PS4000 that we dont use. The question is if it is possible to use the disks in the spare SAN in the one we use for backups? Has anyone tried this?  Thanks Magnus 
EqualLogic PS4000 disks