ZFS lógico referenciado vs referenciado

Question

Depois de enviar um zvol de um pool para outro, fiquei alarmado ao descobrir que apenas metade dos dados estava "lá" (de acordo com REFER ). Então notei no instantâneo enviado que referenced é 302G e logicalreferenced é 150G . Mas depois de enviá-lo para um novo pool, esses dois valores correspondem. Eu não entendo porque isso é, e se qualquer coisa eu pensei logicalreferenced é suposto ser maior que referenced . O 302G é especialmente confuso porque o zvol foi preenchido enviando uma unidade de 150 GB sobre o iSCSI usando dd .

tank/Win10Root         831G   747G   302G  -
tank/Win10Root@send  referenced            302G                   -
tank/Win10Root@send  logicalreferenced     150G                   -

# zfs send tank/Win10Root@send | zfs recv wd/Win10Root

wd/Win10Root           151G  6.24T   151G  -
wd/Win10Root@send  referenced            151G                   -
wd/Win10Root@send  logicalreferenced     150G                   -

EDIT: Postado logicalused (que é 0) em vez de logicalreferenced no acidente

Estas são todas as propriedades de tank/Win10Root . O zvol foi criado com zfs create -V 512G tank/Win10Root .

@ubuntu1:~$ sudo zfs get all tank/Win10Root | sort
NAME            PROPERTY              VALUE                  SOURCE
tank/Win10Root  available             740G                   -
tank/Win10Root  checksum              on                     default
tank/Win10Root  compression           off                    default
tank/Win10Root  compressratio         1.00x                  -
tank/Win10Root  context               none                   default
tank/Win10Root  copies                1                      default
tank/Win10Root  creation              Sat Nov  4 14:21 2017  -
tank/Win10Root  dedup                 off                    default
tank/Win10Root  defcontext            none                   default
tank/Win10Root  fscontext             none                   default
tank/Win10Root  logbias               latency                default
tank/Win10Root  logicalreferenced     150G                   -
tank/Win10Root  logicalused           150G                   -
tank/Win10Root  mlslabel              none                   default
tank/Win10Root  primarycache          all                    default
tank/Win10Root  readonly              off                    default
tank/Win10Root  redundant_metadata    all                    default
tank/Win10Root  refcompressratio      1.00x                  -
tank/Win10Root  referenced            302G                   -
tank/Win10Root  refreservation        528G                   local
tank/Win10Root  reservation           none                   default
tank/Win10Root  rootcontext           none                   default
tank/Win10Root  secondarycache        all                    default
tank/Win10Root  snapdev               hidden                 default
tank/Win10Root  snapshot_count        none                   default
tank/Win10Root  snapshot_limit        none                   default
tank/Win10Root  sync                  standard               default
tank/Win10Root  type                  volume                 -
tank/Win10Root  used                  831G                   -
tank/Win10Root  usedbychildren        0                      -
tank/Win10Root  usedbydataset         302G                   -
tank/Win10Root  usedbyrefreservation  528G                   -
tank/Win10Root  usedbysnapshots       0                      -
tank/Win10Root  volblocksize          8K                     -
tank/Win10Root  volsize               512G                   local
tank/Win10Root  written               0                      -

    

Answer 1

Este é totalmente um caso para verificar a página man para o ZFS:

referenced

The amount of data that is accessible by this dataset, which may or may not be shared with other datasets in the pool. When a snapshot or clone is created, it initially references the same amount of space as the file system or snapshot it was created from, since its contents are identical.

This property can also be referred to by its shortened column name, refer.

e ...

logicalreferenced

The amount of space that is "logically" accessible by this dataset. See the referenced property. The logical space ignores the effect of the compression and copies properties, giving a quantity closer to the amount of data that applications see. However, it does include space consumed by metadata.

This property can also be referred to by its shortened column name, lrefer.

Coisas a considerar:

• Seus zvols eram escassos?
• Quais eram as propriedades de compactação e desduplicação?
• O que há dentro do zvol?