|
|
Sponsored Content
Operating Systems
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:
|
|
3 More Discussions You Might Find Interesting
1. Solaris
I have 2 hard disks ,one hard disk(40gb) completely for windows Os,and the other(120gb) for solaris Os.
In the second hard disk.I have utilised around 10gb for the solaris installation and also partitioned with the available 10gb space for the solaris x86 OS.
Now i need to utilise the... (8 Replies)
Discussion started by: jayaprakash
8 Replies
2. Solaris
I have a question regarding installing recommended patch clusters via ZFS snapshots. Someone wrote a pretty good blog about it here:
Initial Program Load: Live Upgrade to install the recommended patch cluster on a ZFS snapshot
The person's article is similar to what I've done in the past. ... (0 Replies)
Discussion started by: christr
0 Replies
3. Solaris
Hi,
I work as an Oracle Technical consultant (mainly DBA related), and I have used ZFS snapshots on previous projects which has helped me a great deal. I often take snapshots before doing some dev work, and then I can roll it back if I want to start again, or if it goes pear shaped!!
I have... (4 Replies)
Discussion started by: AndyG
4 Replies
LEARN ABOUT FREEBSD
zfsloader
ZFSLOADER(8) BSD System Manager's Manual ZFSLOADER(8) NAME
zfsloader -- kernel bootstrapping final stage DESCRIPTION
zfsloader is an extended variant of loader(8) with added support for booting from ZFS. This document describes only differences from loader(8). ZFS FEATURES
zfsloader supports the following format for specifying ZFS filesystems which can be used wherever loader(8) refers to a device specification: zfs:pool/filesystem: where pool/filesystem is a ZFS filesystem name as described in zfs(8). If /etc/fstab does not have an entry for the root filesystem and vfs.root.mountfrom is not set, but currdev refers to a ZFS filesystem, then zfsloader will instruct kernel to use that filesystem as the root filesystem. ZFS COMMAND EXTENSIONS
lsdev [-v] Lists ZFS pools in addition to disks and partitions. Adding -v shows more ZFS pool details in a format that resembles zpool status output. lszfs filesystem A ZFS extended command that can be used to explore the ZFS filesystem hierarchy in a pool. Lists the immediate children of the filesystem. The filesystem hierarchy is rooted at a filesystem with the same name as the pool. FILES
/boot/zfsloader zfsloader itself. EXAMPLES
Set the default device used for loading a kernel from a ZFS filesystem: set currdev=zfs:tank/ROOT/knowngood: SEE ALSO
gptzfsboot(8), loader(8), zfs(8), zfsboot(8), zfsloader(8), zpool(8) HISTORY
The zfsloader first appeared in FreeBSD 7.3. AUTHORS
This manual page was written by Andriy Gapon <avg@FreeBSD.org>. BSD
September 15, 2014 BSD