Re: another question about zfs compression numbers

[Eugene M. Zheganin]

Hi,

On 04.04.2018 12:35, Patrick M. Hausen wrote:

Hi all,


Am 04.04.2018 um 09:21 schrieb Eugene M. Zheganin :
I'm just trying to understand these numbers:

file size is 232G, it's actual size on the lz4-compressed dataset is 18G, so 
then why is the compressratio only 1.86x ? And why logicalused is 34.2G ? On 
one hand, 34.2G exactlyfits to the 1.86x compresstaio, but still I don't get 
it. dataset is on raidz, 3 spans across 5 disk vdevs, with total of 15 disks if 
it matters:

A sparse file, possibly? The ZFS numbers refer to blocks. "Skipping" zeroes at 
the
VFS layer is not taken into account as fas as I know. Seriously, how should it?
If I'm not mistaken, ZFS will never get to see these empty blocks.

Looks so, thanks. Although it's a mysql tablespace file. But yeah, in 
hex viewer looks like it's filled with zeroes in many places.


Eugene.

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Re: another question about zfs compression numbers

[Patrick M. Hausen]

Hi all,

> Am 04.04.2018 um 09:21 schrieb Eugene M. Zheganin :
> I'm just trying to understand these numbers:
> 
> file size is 232G, it's actual size on the lz4-compressed dataset is 18G, so 
> then why is the compressratio only 1.86x ? And why logicalused is 34.2G ? On 
> one hand, 34.2G exactlyfits to the 1.86x compresstaio, but still I don't get 
> it. dataset is on raidz, 3 spans across 5 disk vdevs, with total of 15 disks 
> if it matters:

A sparse file, possibly? The ZFS numbers refer to blocks. "Skipping" zeroes at 
the
VFS layer is not taken into account as fas as I know. Seriously, how should it?
If I'm not mistaken, ZFS will never get to see these empty blocks.

Patrick
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another question about zfs compression numbers

[Eugene M. Zheganin]

Hello,


I'm just trying to understand these numbers:


file size is 232G, it's actual size on the lz4-compressed dataset is 
18G, so then why is the compressratio only 1.86x ? And why logicalused 
is 34.2G ? On one hand, 34.2G exactlyfits to the 1.86x compresstaio, but 
still I don't get it. dataset is on raidz, 3 spans across 5 disk vdevs, 
with total of 15 disks if it matters:



# du -h
 18G.
# ls -lh
total 19316318
-rw-r-  1 root  wheel   232G  4 апр.  11:29 mp_userCoordsHistory.ibd
# zfs get all data/test
NAME   PROPERTY  VALUE SOURCE
data/test  type  filesystem  -
data/test  creation  ср апр.  4 10:31 2018  -
data/test  used  18,4G   -
data/test  available 9,95T   -
data/test  referenced18,4G   -
data/test  compressratio 1.86x   -
data/test  mounted   yes -
data/test  quota none default
data/test  reservation   none default
data/test  recordsize128K default
data/test  mountpoint/data/test default
data/test  sharenfs  off default
data/test  checksum  on default
data/test  compression   lz4 local
data/test  atime on default
data/test  devices   on default
data/test  exec  on default
data/test  setuidon default
data/test  readonly  off default
data/test  jailedoff default
data/test  snapdir   hidden default
data/test  aclmode   discard default
data/test  aclinheritrestricted default
data/test  canmount  on default
data/test  xattr off temporary
data/test  copies1 default
data/test  version   5   -
data/test  utf8only  off -
data/test  normalization none-
data/test  casesensitivity   sensitive   -
data/test  vscan off default
data/test  nbmandoff default
data/test  sharesmb  off default
data/test  refquota  none default
data/test  refreservationnone default
data/test  primarycache  all default
data/test  secondarycacheall default
data/test  usedbysnapshots   0   -
data/test  usedbydataset 18,4G   -
data/test  usedbychildren0   -
data/test  usedbyrefreservation  0   -
data/test  logbias   latency default
data/test  dedup on inherited from data
data/test  mlslabel  -
data/test  sync  standard default
data/test  refcompressratio  1.86x   -
data/test  written   18,4G   -
data/test  logicalused   34,2G   -
data/test  logicalreferenced 34,2G   -
data/test  volmode   default default
data/test  filesystem_limit  none default
data/test  snapshot_limitnone default
data/test  filesystem_count  none default
data/test  snapshot_countnone default
data/test  redundant_metadataall default

# zpool status
  pool: data
 state: ONLINE
  scan: scrub repaired 0 in 28h24m with 0 errors on Thu Feb 15 13:26:36 
2018

config:

NAMESTATE READ WRITE CKSUM
dataONLINE   0 0 0
  raidz1-0  ONLINE   0 0 0
da2 ONLINE   0 0 0
da3 ONLINE   0 0 0
da4 ONLINE   0 0 0
da5 ONLINE   0 0 0
da6 ONLINE   0 0 0
  raidz1-1  ONLINE   0 0 0
da7 ONLINE   0 0 0
da8 ONLINE   0 0 0
da9 ONLINE   0 0 0
da10ONLINE   0 0 0
da11ONLINE   0 0 0
  raidz1-2  ONLINE   0 0 0
da12ONLINE   0 0 0
da13ONLINE   0 0 0
da14ONLINE   0 0 0
da15ONLINE   0 0 0
da16ONLINE   0 0 0

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