Discussion:
Explanation appreciated: Space usage differences
(too old to reply)
UbuntuNewbie
2015-02-25 14:09:05 UTC
Permalink
After zfs sending ALL of my MAIN pool into BACKUP, i noticed a difference
(4 GB more space usage in MAIN):

NAME PROPERTY VALUE
------------------------------------------
BACKUP size 10,9T
BACKUP allocated 7,99T
BACKUP free 2,89T
BACKUP/20percent refreservation 1,45T
BACKUP available 366G
------------------------------------------
MAIN size 10,9T
MAIN allocated 7,99T
MAIN free 2,88T
MAIN/20percent refreservation 1,45T
MAIN available 362G

Both pools have the same geometry (4+2 RAIDZ2 on 2TB drives)
no changes occurred to compression attribute after filesystems had been
created, so no difference in compression.
So i went on to drill don into the differences and found none, apart from
directories themselves. 1 Example:

for i in "{BACKUP,MAIN}"; do echo $i;bash -c "ls -ls
$i/usr/share/texmf/tex/texinfo;du $i/usr/share/texmf/tex/texinfo";done
{BACKUP,MAIN}
BACKUP/usr/share/texmf/tex/texinfo:
insgesamt 288
169 -rw-r--r-- 1 root root 285382 Apr 17 2012 texinfo.tex
9 -rw-r--r-- 1 root root 2339 Apr 17 2012 txi-cs.tex
9 -rw-r--r-- 1 root root 2505 Apr 17 2012 txi-de.tex
9 -rw-r--r-- 1 root root 2328 Apr 17 2012 txi-en.tex
9 -rw-r--r-- 1 root root 1944 Apr 17 2012 txi-es.tex
9 -rw-r--r-- 1 root root 2460 Apr 17 2012 txi-fr.tex
9 -rw-r--r-- 1 root root 2348 Apr 17 2012 txi-it.tex
9 -rw-r--r-- 1 root root 2243 Apr 17 2012 txi-nb.tex
9 -rw-r--r-- 1 root root 2218 Apr 17 2012 txi-nl.tex
9 -rw-r--r-- 1 root root 2334 Apr 17 2012 txi-pl.tex
9 -rw-r--r-- 1 root root 2142 Apr 17 2012 txi-pt.tex
9 -rw-r--r-- 1 root root 2299 Apr 17 2012 txi-ru.tex
9 -rw-r--r-- 1 root root 2147 Apr 17 2012 txi-sr.tex
9 -rw-r--r-- 1 root root 2574 Apr 17 2012 txi-tr.tex
9 -rw-r--r-- 1 root root 2160 Apr 17 2012 txi-uk.tex

MAIN/usr/share/texmf/tex/texinfo:
insgesamt 519
400 -rw-r--r-- 1 root root 285382 Apr 17 2012 texinfo.tex
9 -rw-r--r-- 1 root root 2339 Apr 17 2012 txi-cs.tex
9 -rw-r--r-- 1 root root 2505 Apr 17 2012 txi-de.tex
9 -rw-r--r-- 1 root root 2328 Apr 17 2012 txi-en.tex
9 -rw-r--r-- 1 root root 1944 Apr 17 2012 txi-es.tex
9 -rw-r--r-- 1 root root 2460 Apr 17 2012 txi-fr.tex
9 -rw-r--r-- 1 root root 2348 Apr 17 2012 txi-it.tex
9 -rw-r--r-- 1 root root 2243 Apr 17 2012 txi-nb.tex
9 -rw-r--r-- 1 root root 2218 Apr 17 2012 txi-nl.tex
9 -rw-r--r-- 1 root root 2334 Apr 17 2012 txi-pl.tex
9 -rw-r--r-- 1 root root 2142 Apr 17 2012 txi-pt.tex
9 -rw-r--r-- 1 root root 2299 Apr 17 2012 txi-ru.tex
9 -rw-r--r-- 1 root root 2147 Apr 17 2012 txi-sr.tex
9 -rw-r--r-- 1 root root 2574 Apr 17 2012 txi-tr.tex
9 -rw-r--r-- 1 root root 2160 Apr 17 2012 txi-uk.tex
304 BACKUP/usr/share/texmf/tex/texinfo
536 MAIN/usr/share/texmf/tex/texinfo

This looks to me like all is well, apart from du reporting a difference i
cannot explain.
Both pools are ashift=12, well aligned. I have no idea, what might have
caused this (and many other) difference(s alike)

Anyone understands, what might be going on here?

Just for completeness: BACKUP only lacks zlog & cache devices:
# zpool status
pool: BACKUP
state: ONLINE
scan: none requested
config:

NAME STATE READ
WRITE CKSUM
BACKUP ONLINE
0 0 0
raidz2-0 ONLINE
0 0 0
usb-ST2000VM_003-1ET164_000000000000-0:0-part1 ONLINE
0 0 0
usb-ST2000VM_003-1ET164_000000000000-0:1-part1 ONLINE
0 0 0
usb-ST2000VM_003-1ET164_000000000000-0:2-part1 ONLINE
0 0 0
usb-WDC_WD20_EARX-00PASB0_000000000000-0:3-part1 ONLINE
0 0 0
usb-ST2000DL_003-9VT166_000000000000-0:4-part1 ONLINE
0 0 0
usb-WDC_WD20_EARX-00PASB0_000000000000-0:5-part1 ONLINE
0 0 0

errors: No known data errors

pool: MAIN
state: ONLINE
scan: scrub repaired 0 in 4h31m with 0 errors on Thu Feb 12 19:06:05 2015
config:

NAME STATE READ WRITE
CKSUM
MAIN ONLINE 0 0
0
raidz2-0 ONLINE 0 0
0
ata-ST2000DM001-1ER164_Z4Z0T0F9-part2 ONLINE 0 0
0
ata-ST2000DM001-1ER164_Z4Z12F05-part2 ONLINE 0 0
0
ata-ST2000DM001-1ER164_Z4Z1368B-part2 ONLINE 0 0
0
ata-ST2000DM001-1ER164_Z4Z11PP1-part2 ONLINE 0 0
0
ata-ST2000DM001-1ER164_Z4Z12JAD-part2 ONLINE 0 0
0
ata-ST2000DM001-1ER164_Z4Z1368R-part2 ONLINE 0 0
0
logs
ata-Solidata_SSD_IDLX-YATOP-000000008-part2 ONLINE 0 0
0
cache
ata-Solidata_SSD_IDLX-YATOP-000000008-part3 ONLINE 0 0
0

errors: No known data errors

And this is zol 0.6.3 (stable)

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Gordan Bobic
2015-02-25 14:13:13 UTC
Permalink
Fragmentation.

zfs receive results in data defragmentation which reduces storage overheads.
Post by UbuntuNewbie
After zfs sending ALL of my MAIN pool into BACKUP, i noticed a difference
NAME PROPERTY VALUE
------------------------------------------
BACKUP size 10,9T
BACKUP allocated 7,99T
BACKUP free 2,89T
BACKUP/20percent refreservation 1,45T
BACKUP available 366G
------------------------------------------
MAIN size 10,9T
MAIN allocated 7,99T
MAIN free 2,88T
MAIN/20percent refreservation 1,45T
MAIN available 362G
Both pools have the same geometry (4+2 RAIDZ2 on 2TB drives)
no changes occurred to compression attribute after filesystems had been
created, so no difference in compression.
So i went on to drill don into the differences and found none, apart from
for i in "{BACKUP,MAIN}"; do echo $i;bash -c "ls -ls
$i/usr/share/texmf/tex/texinfo;du $i/usr/share/texmf/tex/texinfo";done
{BACKUP,MAIN}
insgesamt 288
169 -rw-r--r-- 1 root root 285382 Apr 17 2012 texinfo.tex
9 -rw-r--r-- 1 root root 2339 Apr 17 2012 txi-cs.tex
9 -rw-r--r-- 1 root root 2505 Apr 17 2012 txi-de.tex
9 -rw-r--r-- 1 root root 2328 Apr 17 2012 txi-en.tex
9 -rw-r--r-- 1 root root 1944 Apr 17 2012 txi-es.tex
9 -rw-r--r-- 1 root root 2460 Apr 17 2012 txi-fr.tex
9 -rw-r--r-- 1 root root 2348 Apr 17 2012 txi-it.tex
9 -rw-r--r-- 1 root root 2243 Apr 17 2012 txi-nb.tex
9 -rw-r--r-- 1 root root 2218 Apr 17 2012 txi-nl.tex
9 -rw-r--r-- 1 root root 2334 Apr 17 2012 txi-pl.tex
9 -rw-r--r-- 1 root root 2142 Apr 17 2012 txi-pt.tex
9 -rw-r--r-- 1 root root 2299 Apr 17 2012 txi-ru.tex
9 -rw-r--r-- 1 root root 2147 Apr 17 2012 txi-sr.tex
9 -rw-r--r-- 1 root root 2574 Apr 17 2012 txi-tr.tex
9 -rw-r--r-- 1 root root 2160 Apr 17 2012 txi-uk.tex
insgesamt 519
400 -rw-r--r-- 1 root root 285382 Apr 17 2012 texinfo.tex
9 -rw-r--r-- 1 root root 2339 Apr 17 2012 txi-cs.tex
9 -rw-r--r-- 1 root root 2505 Apr 17 2012 txi-de.tex
9 -rw-r--r-- 1 root root 2328 Apr 17 2012 txi-en.tex
9 -rw-r--r-- 1 root root 1944 Apr 17 2012 txi-es.tex
9 -rw-r--r-- 1 root root 2460 Apr 17 2012 txi-fr.tex
9 -rw-r--r-- 1 root root 2348 Apr 17 2012 txi-it.tex
9 -rw-r--r-- 1 root root 2243 Apr 17 2012 txi-nb.tex
9 -rw-r--r-- 1 root root 2218 Apr 17 2012 txi-nl.tex
9 -rw-r--r-- 1 root root 2334 Apr 17 2012 txi-pl.tex
9 -rw-r--r-- 1 root root 2142 Apr 17 2012 txi-pt.tex
9 -rw-r--r-- 1 root root 2299 Apr 17 2012 txi-ru.tex
9 -rw-r--r-- 1 root root 2147 Apr 17 2012 txi-sr.tex
9 -rw-r--r-- 1 root root 2574 Apr 17 2012 txi-tr.tex
9 -rw-r--r-- 1 root root 2160 Apr 17 2012 txi-uk.tex
304 BACKUP/usr/share/texmf/tex/texinfo
536 MAIN/usr/share/texmf/tex/texinfo
This looks to me like all is well, apart from du reporting a difference i
cannot explain.
Both pools are ashift=12, well aligned. I have no idea, what might have
caused this (and many other) difference(s alike)
Anyone understands, what might be going on here?
# zpool status
pool: BACKUP
state: ONLINE
scan: none requested
NAME STATE READ
WRITE CKSUM
BACKUP ONLINE
0 0 0
raidz2-0 ONLINE
0 0 0
usb-ST2000VM_003-1ET164_000000000000-0:0-part1 ONLINE
0 0 0
usb-ST2000VM_003-1ET164_000000000000-0:1-part1 ONLINE
0 0 0
usb-ST2000VM_003-1ET164_000000000000-0:2-part1 ONLINE
0 0 0
usb-WDC_WD20_EARX-00PASB0_000000000000-0:3-part1 ONLINE
0 0 0
usb-ST2000DL_003-9VT166_000000000000-0:4-part1 ONLINE
0 0 0
usb-WDC_WD20_EARX-00PASB0_000000000000-0:5-part1 ONLINE
0 0 0
errors: No known data errors
pool: MAIN
state: ONLINE
scan: scrub repaired 0 in 4h31m with 0 errors on Thu Feb 12 19:06:05 2015
NAME STATE READ WRITE
CKSUM
MAIN ONLINE 0
0 0
raidz2-0 ONLINE 0
0 0
ata-ST2000DM001-1ER164_Z4Z0T0F9-part2 ONLINE 0
0 0
ata-ST2000DM001-1ER164_Z4Z12F05-part2 ONLINE 0
0 0
ata-ST2000DM001-1ER164_Z4Z1368B-part2 ONLINE 0
0 0
ata-ST2000DM001-1ER164_Z4Z11PP1-part2 ONLINE 0
0 0
ata-ST2000DM001-1ER164_Z4Z12JAD-part2 ONLINE 0
0 0
ata-ST2000DM001-1ER164_Z4Z1368R-part2 ONLINE 0
0 0
logs
ata-Solidata_SSD_IDLX-YATOP-000000008-part2 ONLINE 0
0 0
cache
ata-Solidata_SSD_IDLX-YATOP-000000008-part3 ONLINE 0
0 0
errors: No known data errors
And this is zol 0.6.3 (stable)
To unsubscribe from this group and stop receiving emails from it, send an
To unsubscribe from this group and stop receiving emails from it, send an email to zfs-discuss+***@zfsonlinux.org.
UbuntuNewbie
2015-02-25 14:23:44 UTC
Permalink
Ah, ok. makes sense. Thank you.

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