Re: [zfs-discuss] question about COW and snapshots

2011-06-18 Thread Toby Thain
On 18/06/11 12:44 AM, Michael Sullivan wrote: ... Way off-topic, but Smalltalk and its variants do this by maintaining the state of everything in an operating environment image. ...Which is in memory, so things are rather different from the world of filesystems. --Toby But then again, I

Re: [zfs-discuss] question about COW and snapshots

2011-06-17 Thread Ross Walker
On Jun 16, 2011, at 7:23 PM, Erik Trimble erik.trim...@oracle.com wrote: On 6/16/2011 1:32 PM, Paul Kraus wrote: On Thu, Jun 16, 2011 at 4:20 PM, Richard Elling richard.ell...@gmail.com wrote: You can run OpenVMS :-) Since *you* brought it up (I was not going to :-), how does VMS'

Re: [zfs-discuss] question about COW and snapshots

2011-06-17 Thread Michael Sullivan
On 17 Jun 11, at 21:02 , Ross Walker wrote: On Jun 16, 2011, at 7:23 PM, Erik Trimble erik.trim...@oracle.com wrote: On 6/16/2011 1:32 PM, Paul Kraus wrote: On Thu, Jun 16, 2011 at 4:20 PM, Richard Elling richard.ell...@gmail.com wrote: You can run OpenVMS :-) Since *you* brought it up

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Simon Walter
On 06/16/2011 09:09 AM, Erik Trimble wrote: We had a similar discussion a couple of years ago here, under the title A Versioning FS. Look through the archives for the full discussion. The jist is that application-level versioning (and consistency) is completely orthogonal to filesystem-level

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Erik Trimble
On 6/16/2011 12:09 AM, Simon Walter wrote: On 06/16/2011 09:09 AM, Erik Trimble wrote: We had a similar discussion a couple of years ago here, under the title A Versioning FS. Look through the archives for the full discussion. The jist is that application-level versioning (and consistency)

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Toby Thain
On 16/06/11 3:09 AM, Simon Walter wrote: On 06/16/2011 09:09 AM, Erik Trimble wrote: We had a similar discussion a couple of years ago here, under the title A Versioning FS. Look through the archives for the full discussion. The jist is that application-level versioning (and consistency) is

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Frank Van Damme
Op 15-06-11 05:56, Richard Elling schreef: You can even have applications like databases make snapshots when they want. Makes me think of a backup utility called mylvmbackup, which is written with Linux in mind - basically it locks mysql tables, takes an LVM snapshot and releases the lock (and

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Frank Van Damme
Op 15-06-11 14:30, Simon Walter schreef: Anyone know how Google Docs does it? Anyone from Google on the list? :-) Seriously, this is the kind of feature to be found in Serious CMS applications, like, as already mentioned, Alfresco. -- No part of this copyright message may be reproduced, read

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Casper . Dik
Op 15-06-11 05:56, Richard Elling schreef: You can even have applications like databases make snapshots when they want. Makes me think of a backup utility called mylvmbackup, which is written with Linux in mind - basically it locks mysql tables, takes an LVM snapshot and releases the lock (and

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Nico Williams
On Thu, Jun 16, 2011 at 8:51 AM, casper@oracle.com wrote: If a database engine or another application keeps both the data and the log in the same filesystem, a snapshot wouldn't create inconsistent data (I think this would be true with vim and a large number of database engines; vim will

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Nico Williams
That said, losing committed transactions when you needed and thought you had ACID semantics... is bad. But that's implied in any restore-from-backups situation. So you replicate/distribute transactions so that restore from backups (or snapshots) is an absolutely last resort matter, and if you

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Richard Elling
On Jun 16, 2011, at 12:09 AM, Simon Walter wrote: On 06/16/2011 09:09 AM, Erik Trimble wrote: We had a similar discussion a couple of years ago here, under the title A Versioning FS. Look through the archives for the full discussion. The jist is that application-level versioning (and

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Paul Kraus
On Thu, Jun 16, 2011 at 4:20 PM, Richard Elling richard.ell...@gmail.com wrote: You can run OpenVMS :-) Since *you* brought it up (I was not going to :-), how does VMS' versioning FS handle those issues ? I know that SAM-FS has rules for _when_ copies of a file are made, so that intermediate

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Freddie Cash
The OpenVMS filesystem is what you are looking for. On Thu, Jun 16, 2011 at 12:09 AM, Simon Walter si...@gikaku.com wrote: On 06/16/2011 09:09 AM, Erik Trimble wrote: We had a similar discussion a couple of years ago here, under the title A Versioning FS. Look through the archives for the

Re: [zfs-discuss] question about COW and snapshots

2011-06-16 Thread Erik Trimble
On 6/16/2011 1:32 PM, Paul Kraus wrote: On Thu, Jun 16, 2011 at 4:20 PM, Richard Elling richard.ell...@gmail.com wrote: You can run OpenVMS :-) Since *you* brought it up (I was not going to :-), how does VMS' versioning FS handle those issues ? It doesn't, per se. VMS's filesystem has a

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Simon Walter
On 06/15/2011 12:56 PM, Richard Elling wrote: So now my (ignorant) question: can ZFS make a snapshot every time it's written to? I hope not, that would suck most heinously. Can all writes be available as snapshots so all previous versions are available? That would suck worse. Why would

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Simon Walter
Thanks for the comments. So ZFS alone cannot do what I'd like. In linux there Gamin. Or there is also a kernel patch which gives you /proc/fschanges. I could monitor this file for changes and take a snapshot when a change occurs or under certain circumstances. However, the Linux COW type FS

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Edward Ned Harvey
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of Richard Elling That would suck worse. Don't mind Richard. He is of the mind that ZFS is perfect for everything just the way it is, and anybody who wants anything different should adjust

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Darren J Moffat
On 06/15/11 12:29, Edward Ned Harvey wrote: From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of Richard Elling That would suck worse. Don't mind Richard. He is of the mind that ZFS is perfect for everything just the way it is, and anybody who

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Simon Walter
On 06/15/2011 07:45 PM, Simon Walter wrote: Thanks for the comments. So ZFS alone cannot do what I'd like. In linux there Gamin. Or there is also a kernel patch which gives you /proc/fschanges. I could monitor this file for changes and take a snapshot when a change occurs or under certain

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Simon Walter
On 06/15/2011 09:01 PM, Toby Thain wrote: I know I've certainly had many situations where people wanted to snapshot or rev individual files everytime they're modified. As I said - perfect example is Google Docs. Yes it is useful. But no, it's not what ZFS does. Exactly versions of a whole

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Michael Schuster
On 15.06.2011 14:30, Simon Walter wrote: Another one is that snapshots are per-filesystem, while the intention here is to capture a document in one user session. Taking a snapshot will of course say nothing about the state of other user sessions. Any document in the process of being saved by

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Jim Klimov
:48 Subject: Re: [zfs-discuss] question about COW and snapshots To: zfs-discuss@opensolaris.org Thanks for the comments. So ZFS alone cannot do what I'd like. In linux there Gamin. Or there is also a kernel patch which gives you /proc/fschanges. I could monitor this file for changes and take

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Jim Klimov
How you interpret on every write depends on where in the stack you are coming from. If you think about an application a write is whey you save the document but at the ZPL layer that is multiple write(2) calls and maybe even some rename(2)/unlink(2)/close(2) calls as well. That's

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Eric D. Mudama
On Wed, Jun 15 at 7:29, Edward Ned Harvey wrote: From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of Richard Elling That would suck worse. Don't mind Richard. He is of the mind that ZFS is perfect for everything just the way it is, and

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Richard Elling
On Jun 15, 2011, at 4:45 AM, Darren J Moffat wrote: On 06/15/11 12:29, Edward Ned Harvey wrote: From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of Richard Elling That would suck worse. Don't mind Richard. He is of the mind that ZFS is

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Toby Thain
On 15/06/11 8:30 AM, Simon Walter wrote: On 06/15/2011 09:01 PM, Toby Thain wrote: I know I've certainly had many situations where people wanted to snapshot or rev individual files everytime they're modified. As I said - perfect example is Google Docs. Yes it is useful. But no, it's not

Re: [zfs-discuss] question about COW and snapshots

2011-06-15 Thread Erik Trimble
We had a similar discussion a couple of years ago here, under the title A Versioning FS. Look through the archives for the full discussion. The jist is that application-level versioning (and consistency) is completely orthogonal to filesystem-level snapshots and consistency. IMHO, they

Re: [zfs-discuss] question about COW and snapshots

2011-06-14 Thread Edward Ned Harvey
From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss- boun...@opensolaris.org] On Behalf Of Simon Walter I'm looking to create a NAS with versioning for non-technical users (Windows and Mac). I want the users to be able to simply save a file, and a revision/snapshot is created. I

Re: [zfs-discuss] question about COW and snapshots

2011-06-14 Thread Richard Elling
On Jun 14, 2011, at 10:25 AM, Simon Walter wrote: I'm looking to create a NAS with versioning for non-technical users (Windows and Mac). I want the users to be able to simply save a file, and a revision/snapshot is created. I could use a revision control software like SVN (it has