meta data for this page
This is an old revision of the document!
ZFS
Creating ZFS dataset
zpool create INBOX /dev/loop0 /dev/loop1 /dev/loop2 /dev/loop3
# zpool list NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT INBOX 780M 448K 780M 0% 1.00x ONLINE -
# zpool status
pool: INBOX
state: ONLINE
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
INBOX ONLINE 0 0 0
loop0 ONLINE 0 0 0
loop1 ONLINE 0 0 0
loop2 ONLINE 0 0 0
loop3 ONLINE 0 0 0
errors: No known data errors
Dataset “INBOX” is also automatically created based on zpool name “INBOX”. It is mounted as /INBOX
# zfs list NAME USED AVAIL REFER MOUNTPOINT INBOX 400K 748M 112K /INBOX
Mount dataset
zfs mount INBOX
Create more datasets in pool
zfs create <pool name>/<data set name>
Add new block device (disc) to online pool
zpool add INBOX /dev/loop4
Deduplication and compression
Enable compression and dedupliaction in parent dataset (will be inherited by childs)
zfs set dedup=on INBOX zfs set compression=on INBOX
But new attributed applies only to newly written data.
NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT INBOX 975M 724M 251M 74% 1.00x ONLINE -
The same data copied again to dataset after compression enabled
NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT INBOX 975M 563M 412M 57% 1.00x ONLINE -
zdb -S INBOX
zdb -b INBOX
Tests:
Filesystem was tested with 648MiB of e-mail stored in Maildir format (lots of binary attachment encoded as BASE64).
SquashFS=365MB vs ZFS=563MB
Deduplication:
Deduplication on file level works on ZFS and SquashFS (the same folder copied again).
Deduplication of 2 different 32MB blobs, with file concatenated from | 0 | blob1 | 0 | blob2 | 0 | blob1 | 0 | blob2 |0|
Deduplication on the same attachment inside different email doesn't work in ZFS.