# [FreeNAS] Upgraded ZFS from v15 to v28... mysteriously lost 5% of usable volume size



## Evilsgenius (Sep 6, 2013)

I just upgraded a storage box that was running FreeNAS v8.2.0 to FreeNAS v9.1.0.

It was previously running 15x 3 TB Drives (0S03230 Hitachi drives with 512 kB sector sizes) configured in RAID-Z2 with the total usable space on the array created by ZFS v15 being 34.6 TB.

After the upgrade I added 15 more 3 TB drives (WD30EZRX with 4k sectors and wdidle3 manually set to disabled) and created another 15x 3 TB RAID-Z2. This new array created by ZFS v28 is reporting only 32.9 TB of total usable space, which is 5% smaller than the original array.

I read several posts from different forums that said there might be differences when using older disks with 512 kB sectors vs new disks with 4k sectors, therefore I copied the data from the old 34.6 TB array to the new 32.9 TB array and then deleted the old array. After recreating it under 9.1.0 which again uses ZFS v28, this new array made up of the exact same old disks with 512 kB sectors reports the reduced size of 32.9 TB as well.

In both cases this is despite the fact that the volume creation wizard showed an estimated capacity of 35.46 TB after subtracting the capacity of the parity disks during the creation process. I got the same results when I tried creating encrypted volumes as well.

I just want to know if there is a known disk space usage difference between ZFS version 15 and version 28 that no one is actively talking about, or is this a configuration problem with the FreeNAS OS?

A 5% storage capacity penalty just seems like a pretty steep price to pay for upgrading.


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## SirDice (Sep 6, 2013)

Evilsgenius said:
			
		

> I just upgraded a storage box that was running FreeNAS v8.2.0 to FreeNAS v9.1.0.


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## Evilsgenius (Sep 6, 2013)

Yes, I'm aware that FreeNAS is a derivative product, however I already checked in with their official forums yesterday and got zero responses.

http://forums.freenas.org/threads/u...ks-same-zpool-config-5-smaller-volumes.14789/

I just want to confirm that this isn't a known ZFS version 15 vs 28 issue before I go further down that rabbit hole.

Thanks*.*


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## Sylhouette (Sep 7, 2013)

Could this be you answer? http://cuddletech.com/blog/pivot/entry.php?id=1013. Maybe something changed between ZFS version 15 and version 28 regarding the reserved space. There are more features added, and I think they need some extra space.

Regards 
Johan


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