On Sun, May 30, 2010 at 23:37, Sandon Van Ness <san...@van-ness.com> wrote:
> I just wanted to make sure this is normal and is expected. I fully
> expected that as the file-system filled up I would see more disk space
> being used than with other file-systems due to its features but what I
> didn't expect was to lose out on ~500-600GB to be missing from the total
> volume size right at file-system creation.
>
> Comparing two systems, one being JFS and one being ZFS, one being raidz2
> one being raid6. Here is the differences I see:
>
> ZFS:
> r...@opensolaris: 11:22 AM :/data# df -k /data
> Filesystem kbytes used avail capacity Mounted on
> data 17024716800 258872352 16765843815 2% /data
>
> JFS:
> r...@sabayonx86-64: 11:22 AM :~# df -k /data2
> Filesystem 1K-blocks Used Available Use% Mounted on
> /dev/sdd1 17577451416 2147912 17575303504 1% /data2
>
> zpool list shows the raw capacity right?
>
> r...@opensolaris: 11:25 AM :/data# zpool list data
> NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT
> data 18.1T 278G 17.9T 1% 1.00x ONLINE -
>
> Ok, i would expect it to be rounded to 18.2 but that seems about right
> for 20 trillion bytes (what 20x1 TB is):
>
> r...@sabayonx86-64: 11:23 AM :~# echo | awk '{print
> 20000000000000/1024/1024/1024/1024}'
> 18.1899
>
> Now minus two drives for parity:
>
> r...@sabayonx86-64: 11:23 AM :~# echo | awk '{print
> 18000000000000/1024/1024/1024/1024}'
> 16.3709
>
> Yet when running zfs list it also lists the amount of storage
> significantly smaller:
>
> r...@opensolaris: 11:23 AM :~# zfs list data
> NAME USED AVAIL REFER MOUNTPOINT
> data 164K 15.9T 56.0K /data
>
> I would expect this to be 16.4T.
>
> Taking the df -k values JFS gives me a total volume size of:
>
> r...@sabayonx86-64: 11:31 AM :~# echo | awk '{print
> 17577451416/1024/1024/1024}'
> 16.3703
>
> and zfs is:
>
> r...@sabayonx86-64: 11:31 AM :~# echo | awk '{print
> 17024716800/1024/1024/1024}'
> 15.8555
>
> So basically with JFS I see no decrease in total volume size but a huge
> difference on ZFS. Is this normal/expected? Can anything be disabled to
> not lose 500-600 GB of space?
This may be the answer:
http://www.cuddletech.com/blog/pivot/entry.php?id=1013
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