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Solaris
Understanding ZFS Snapshots - why will it utilize space ?
Post 303013453 by Peasant on Wednesday 21st of February 2018 02:08:33 PM
02-21-2018
Moderator
In a nutshell yes.
It is confusing a bit from user perspective,zfs used/usedsnap etc.
I would recommend reading about snapshots and COW in general.
Any tech that uses those, basically works on same principle.
Range is from filesystems (zfs,brtfs etc.) to enterprise storage systems with proprietary HW/SW.
Everything works the same way more or less.
Lets say blocks need to be modified due to write request.
Instead of overwriting blocks, zfs will write a change a new blocks, while old blocks will still contain old data, and that data will remain on disk until needed and is considered free.
This is what enables snapshots,clones, rollback etc. which is fundamental design of zfs filesystem/volume manager.
If there is a snapshot (pointers to old blocks at the time snapshot is taken), those will not be considered free but will remain unchanged (read the blog i posted, it is extremely good).
This is what enables snapshots,clones, rollback etc.
ZFS is a great and fairly complex product code wise with a lot of time and effort put into it.
One can only put a hat down to those SUN engineers behind it.
Those guys were ahead of their time.
Also, i must apologize upfront for information given in this post due to minor alcohol intoxication
This happens you know, when you are in automation business.
As a folks say here
'An idle mind is a devils workshop'
Regards
Peasant.
It is confusing a bit from user perspective,zfs used/usedsnap etc.
I would recommend reading about snapshots and COW in general.
Any tech that uses those, basically works on same principle.
Range is from filesystems (zfs,brtfs etc.) to enterprise storage systems with proprietary HW/SW.
Everything works the same way more or less.
Lets say blocks need to be modified due to write request.
Instead of overwriting blocks, zfs will write a change a new blocks, while old blocks will still contain old data, and that data will remain on disk until needed and is considered free.
This is what enables snapshots,clones, rollback etc. which is fundamental design of zfs filesystem/volume manager.
If there is a snapshot (pointers to old blocks at the time snapshot is taken), those will not be considered free but will remain unchanged (read the blog i posted, it is extremely good).
This is what enables snapshots,clones, rollback etc.
ZFS is a great and fairly complex product code wise with a lot of time and effort put into it.
One can only put a hat down to those SUN engineers behind it.
Those guys were ahead of their time.
Also, i must apologize upfront for information given in this post due to minor alcohol intoxication
This happens you know, when you are in automation business.
As a folks say here
'An idle mind is a devils workshop'
Regards
Peasant.
This User Gave Thanks to Peasant For This Post:
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LEARN ABOUT DEBIAN
backintime-gnome
backintime-gnome(1) USER COMMANDS backintime-gnome(1) NAME
backintime-gnome - a simple backup tool for Gnome. SYNOPSIS
backintime-gnome [ [--snapshots] path | --backup | --backup-job | --snapshots-path | --snapshots-list | --snapshots-list-path | --last-snapshot | --last-snapshot-path | --help | --version | --license ] DESCRIPTION
Back In Time is a simple backup tool for Linux. This is the Gnome version. For more information about Back In Time see backintime man page. If you want to run it as root you need to use 'gksu'. OPTIONS
path go directly to the specified file/folder -s, --snapshots show snapshots dialog for the specified path (only if there is no other dialog displayed) -b, --backup take a snapshot now (if needed) --backup-job take a snapshot (if needed) depending on schedule rules (used for cron jobs) --snapshots-path display path where is saves the snapshots (if configured) --snapshots-list display the list of snapshot IDs (if any) --snapshots-list-path display the paths to snapshots (if any) --last-snapshot display last snapshot ID (if any) --last-snapshot-path display the path to the last snapshot (if any) -h, --help display a short help -v, --version show version --license show license SEE ALSO
backintime, backintime-kde4. Back In Time also has a website: http://backintime.le-web.org AUTHOR
This manual page was written by BIT Team(<bit-team@lists.launchpad.net>). version 1.0.10 Mars 2009 backintime-gnome(1)