Howdy,
Cross-posted to: zfs-discuss@opensolaris.org
I am playing around with the latest Read-Write ZFS on Leopard and am
confused about why the available size of my admittedly tiny test pool
(100 MB) is showing at ~2/3 (63 MB) of the expected capacity. I used
mkfile to create test "disks". Is this due to normal ZFS overhead? If
so, how can I list / view / examine these properties? I don't think
it's compression related (BTW, is compression ON or OFF by default in
OS X's current implementation of ZFS?).
tcpb:jpool avatar$ uname -a
Darwin tcpb.local 9.1.0 Darwin Kernel Version 9.1.0: Wed Oct 31
17:48:21 PDT 2007; root:xnu-1228.0.2~1/RELEASE_PPC Power Macintosh
tcpb:jpool avatar$ sw_vers
ProductName: Mac OS X
ProductVersion: 10.5.1
BuildVersion: 9B18
tcpb:aguas avatar$ kextstat | grep zfs
125 0 0x3203a000 0xcf000 0xce000 com.apple.filesystems.zfs
(6.0) <7 6 5 2>
I created a test pool in the "aguas" directory on an external firewire
HDD:
cd to my zfs test directory: "aguas" on an external HDD..
cd /Volumes/jDrive/aguas/
Create 5 100MB files to act as "Disks" in my Pool...
sudo mkfile 100M disk1
sudo mkfile 100M disk2
sudo mkfile 100M disk3
sudo mkfile 100M disk4
sudo mkfile 100M disk5
Create MIRROR'd Pool, "jpool" using 1st two Disks...
sudo zpool create jpool mirror /Volumes/jDrive/aguas/disk1 /Volumes/
jDrive/aguas/disk2
zpool list =====>
NAME SIZE USED AVAIL CAP HEALTH
ALTROOT
jpool 95.5M 151K 95.4M 0% ONLINE
-
zpool status =====>
pool: jpool
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
jpool ONLINE 0 0 0
mirror ONLINE 0 0 0
/Volumes/jDrive/aguas/disk1 ONLINE 0 0 0
/Volumes/jDrive/aguas/disk2 ONLINE 0 0 0
errors: No known data errors
=====
Added a spare:
sudo zpool add jpool spare /Volumes/jDrive/aguas/disk5
zpool status =====>
pool: jpool
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
jpool ONLINE 0 0 0
mirror ONLINE 0 0 0
/Volumes/jDrive/aguas/disk1 ONLINE 0 0 0
/Volumes/jDrive/aguas/disk2 ONLINE 0 0 0
spares
/Volumes/jDrive/aguas/disk5 AVAIL
errors: No known data errors
=====
"jpool" NOW SHOWS UP ON THE FINDER...
tcpb:aguas avatar$ df -h
Filesystem Size Used Avail Capacity Mounted on
/dev/disk0s3 112Gi 103Gi 8.7Gi 93% /
devfs 114Ki 114Ki 0Bi 100% /dev
fdesc 1.0Ki 1.0Ki 0Bi 100% /dev
map -hosts 0Bi 0Bi 0Bi 100% /net
map auto_home 0Bi 0Bi 0Bi 100% /home
/dev/disk1s14 56Gi 50Gi 5.4Gi 91% /Volumes/jDrive ONE
/dev/disk1s10 75Gi 68Gi 7.3Gi 91% /Volumes/jDrive
/dev/disk1s12 55Gi 52Gi 2.5Gi 96% /Volumes/Free 55
jpool 63Mi 59Ki 63Mi 1% /Volumes/jpool
=====
OK, GIVEN:
zpool list =====>
NAME SIZE USED AVAIL CAP HEALTH
ALTROOT
jpool 95.5M 151K 95.4M 0% ONLINE
-
*WHY* ONLY 63MB?!?:
jpool 63Mi 59Ki 63Mi 1% /Volumes/jpool
More info (I turned COMPRESSION on after I noticed the
discrepancy.) ...
tcpb:jpool avatar$ sudo zfs get all jpool =====>
NAME PROPERTY VALUE SOURCE
jpool type filesystem -
jpool creation Tue Nov 20 14:48 2007 -
jpool used 392K -
jpool available 63.1M -
jpool referenced 59K -
jpool compressratio 1.00x -
jpool mounted yes -
jpool quota none default
jpool reservation none default
jpool recordsize 128K default
jpool mountpoint /Volumes/jpool default
jpool sharenfs off default
jpool checksum on default
jpool compression on local
jpool atime on default
jpool devices on default
jpool exec on default
jpool setuid on default
jpool readonly off default
jpool zoned off default
jpool snapdir hidden default
jpool aclmode groupmask default
jpool aclinherit secure default
jpool canmount on default
jpool shareiscsi off default
jpool xattr on default
jpool copies 1 default
=====
So, zpool list =
NAME SIZE USED AVAIL CAP HEALTH
ALTROOT
jpool 95.5M 479K 95.0M 0% ONLINE -
While zfs list =
NAME USED AVAIL REFER MOUNTPOINT
jpool 392K 63.1M 59K /Volumes/jpool
-and-
tcpb:aguas avatar$ df -h
jpool 63Mi 59Ki 63Mi 1% /Volumes/jpool
OK, so the pool (as referenced by zpool) shows the expected SIZE but
the filesystem part (as reference by zfs and df) shows ~2/3 the
expected SIZE.
Hmmm...this leads to something about ZFS that I was confused about: I
thought that I had to use the zfs command to create a filesystem on my
pool before it was useable. I was surprised when "jpool" popped up on
my Desktop as a removable drive as soon as I created it with zpool.
Is there a default filesystem created automatically when the pool is
created? If so, does it cover the whole pool?
Again, the pool = 100MB but the fs = 64MB.
Maybe this is just fs overhead (if so, what/when/how to examine?) and
maybe my pool is too small. If the test pool was a more reasonable
10GB and the 40MB is normal fs overhead than we are talking 0.4% as
opposed to 33%(40MB) on a test pool of 100MB. If my test pool was
10GB, then I probably wouldn't even have noticed.
OK! Thanks for reading this if you got all the way down here!
SUMMARY:
1) Why the difference between pool size and fs capacity?
2) If this is normal overhead, then how to you examine these aspects
of the fs (commands to use, background links to read, etc. (If you say
RTFM then please supply a page number for "817-2271.pdf"))?
3) What's the relationship between pools (zpool) and filesystems (zfs
command)? / Is there a default fs created hwne the pool is created?
4) BONUS QUESTION: Is Sun currently using / promoting / shipping
hardware that *boots* ZFS? (e.g. last I checked even stuff like
"Thumper" did not use ZFS for the 2 mirror'd boot drives (UFS?) but
used ZFS for the 10,000 other drives (OK, maybe there aren't 10,000
drive but there sure are a lot)).
5) BONUS QUESTION #2: How does a frustrated yet extremely seasoned Mac/
OS X technician with a terrific Solaris background find happiness by
landing a job at his other favorite company, Sun? (My "friend" wants
to know.)
6) FINAL QUESTION (2 parts): (a) When will we see default booting to
ZFS? & (b) [When] will we see ZFS as the default fs on OS X?
Thanks!
-Anonymous Mac Tech
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