Zpool size explained - help

[heimos]

Hi guys,

I am looking for help in understanding the meaning behind the size of the pool that I created for my FreeNAS box. When I run the command zpool list, I see that the size of the pool is 14.5TB of which 11.7 TB have been allocated and 2.81 TB is free

[root@nas2 ~]# zpool list
NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
boot 59.5G 644M 58.9G - - 1% 1.00x ONLINE -
vol1 14.5T 11.7T 2.81T - 45% 80% 1.00x ONLINE /mnt

However when I go to the Volume manager I see a different picture. (see attached image).

My volume is set up in RAIDZ (4 x 4TB ) disks, so one disk is removed for parity so that leaves 12 TB but why am I seeing a difference in free volume. Zpool list show 2.81 TB and Volume manager only shows 3.2 and 2.0 TB.

 

[CraigD]

Have you read this?

https://forums.freenas.org/index.php?threads/zfs-raid-size-and-reliability-calculator.28191/

Have Fun

 

[saikee]

I am new to FreeNAS too but I note FreeNAS in "View disk" reports the storgae in TB which is the "unused" or new disk capacity of the hard disk. Once put into operation the hard disk needs to provide room for the GPT partition table, boot sector regardless if it is used or not plus a substantial area for the filing index which could be anything around 5% even for the Windows' NTFS filing system.

The unit given in Volume Manager is TiB which is in unit of 1024 and not 1000 so even if a unsed raw 16TB hard disk storage could have only 16/1.024 or 15.625Tib.

Thus if your 16TB hard disk system has a total of usable 14.5Tib then the overhead, from GPT partition table boot, sector plus the filing indexing system, takes up about 7% of the available space. This is not unusual if you are using the ZFS filing system which is considerably more sophisticated than Windows NTFS system.

My own FreeNAS has 21.8TiB from 3x8TB hard disks. The overhead is also 7%.