Creating ZFS pool with slack space

[chandeliho]

My setup has 5 drives that are all the same model - currently I believe when creating the data partition the entire disk is used (aside from the swap). Is there a way to add in some slack space that isn't partitioned at all? My concern is that if one of my drives die, and I have to replace it with a drive from another manufacturer, the size of the replacement might not exactly match the drive that died. If the size of the replacement is even slightly smaller (since drives from different manufacturers may have slightly different byte counts), then repairing the array might have trouble, right?

 

[chandeliho]

Is this not a supported usage model? Is it expected that every drive is identical? Anyone know at all?

 

[cyberjock]

From personal experience different hardware versions of the same hard drive can give different drive sizes. I RMA'd a hard drive that was part of a RAID-6 a few years ago and the replacement drive was 14MB smaller. Ever since that time I have ALWAYS left 10GB of free space on any arrays I build.

Unfortunately, I don't know if that's possible. I'm still experimenting with Linux and run Freenas 8 in a virtual machine just so I can get comfortable with it. Hopefully someone can comment as I'd like to know if it's possible.

 

[peterh]

You may partition the disks and use the partitions as building blocks for a zpool.

 

[ProtoSD]

The swap space at the beginning is also a convenient way to create a buffer. You can recreate the ZFS partition on a disk without the swap and the swap on the other disks will continue to function, so you could just create a bigger swap at the beginning of each disk. The swap size setting is in the GUI under Settings->Advanced.