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ext3cow FS?
by Scott R. Ehrlich
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I just found an article comparing Ubuntu Linux (7.04) to Vista, and one of the
areas they compare is backups. In that section they mention ext3cow, which was the first time I'd heard of it. What are people's insights of ext3cow? I haven't had to recompile a kernel in ages - it seems the default ones, for the most part, for Ubuntu and CentOS, anyway, are fully robust to handle whatever I throw at them. So how does something like ext3cow for some kind of backup/restore fair? What other similar tools do people use? How about for systems that are actively in use that I may opt to insert this functionality, ideally without rebooting, but if needed, I would. Thanks. Scott -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Tom Metro-12
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Scott R. Ehrlich wrote:
> I just found an article comparing Ubuntu Linux (7.04) to Vista... Link? > In that section they mention ext3cow... Link? Oh, here it is: http://www.ext3cow.com/ (Thanks Bill) Also : http://en.wikipedia.org/wiki/Ext3cow > ...which was the first time I'd heard of it. Me too. Thanks for mentioning it. > I haven't had to recompile a kernel in ages - it seems the default > ones, for the most part, for Ubuntu and CentOS, anyway, are fully > robust to handle whatever I throw at them. And your point is? Are you implying use of ext3cow requires compiling a custom kernel? The blog posting Bill linked to: http://cmynhier.blogspot.com/2007/05/ext3cow-snapshots-for-ext3.html says: One of the design features of ext3cow is that changes to support snapshotting were localized to the ext3 code itself... This certainly makes life easy, as it can be used with otherwise stock kernels. It doesn't say explicitly, but I assume the author is implying that it can be built as a module. > What are people's insights of ext3cow? Per this from the blog posting: Multiple versions of a file can share data blocks, as long as those data blocks haven't changed. I'd say it fairs better than most other snapshotting technologies available on Linux. The other options generally operate at the file level, rather than at the block level. This sounds comparable to what is done in NetApp's WAFL[1] or Sun's ZFS[2], both file systems designed with snapshotting in mind. You can do snapshots with LVM, but I'm pretty sure it isn't as efficient. To quote Wikipedia, "Block-level snapshotting is almost always less space-efficient than direct file system support for snapshots."[3] 1. http://en.wikipedia.org/wiki/Write_Anywhere_File_Layout 2. http://en.wikipedia.org/wiki/Zfs 3. http://en.wikipedia.org/wiki/Snapshot_%28computer_storage%29 What I don't see in either the ext3cow site or the blog posting is an indication of the maturity or stability of the software, aside from the 0.2 version number. I'd have to assume it is still in an experimental state. > So how does something like ext3cow for some kind of backup/restore fair? I'd assume it supplements a backup strategy just as any other snapshotting[3] technology does. It permits you to more quickly access past versions of a file, and to efficiently store more versions. Of course that's contingent upon the file system being accessible, and thus you still need to pair it with traditional backup techniques. > What other similar tools do people use? rsnapshot[4] and other similar tools built around rsync have traditionally been the approach to attaining snapshot functionality on Linux. I see mention of LVM snapshots some too. 4. http://www.rsnapshot.org/ -Tom -- Tom Metro Venture Logic, Newton, MA, USA "Enterprise solutions through open source." Professional Profile: http://tmetro.venturelogic.com/ -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Kristian Erik Hermansen
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On Sun, May 4, 2008 at 8:10 AM, Scott R. Ehrlich <scott@...> wrote:
> I just found an article comparing Ubuntu Linux (7.04) to Vista, and one of > the areas they compare is backups. In that section they mention ext3cow, > which was the first time I'd heard of it. > > What are people's insights of ext3cow? I haven't had to recompile a > kernel in ages - it seems the default ones, for the most part, for Ubuntu > and CentOS, anyway, are fully robust to handle whatever I throw at them. > > So how does something like ext3cow for some kind of backup/restore fair? > What other similar tools do people use? How about for systems that are > actively in use that I may opt to insert this functionality, ideally without > rebooting, but if needed, I would. I'll just wait for ZFS on Linux, but it's nice to know ext3cow is an option too :-) -- Kristian Erik Hermansen -- "Clever ones don't want the future told. They make it." -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Scott R. Ehrlich
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On Sun, 4 May 2008, Tom Metro wrote:
> Scott R. Ehrlich wrote: >> I just found an article comparing Ubuntu Linux (7.04) to Vista...> > Link? > Sorry - http://www.informationweek.com/news/software/linux/showArticle.jhtml?articleID=199201179&pgno=7&queryText=&isPrev= or http://tinyurl.com/5wepbp Scott -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Jerry Feldman-2
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On Sun, 4 May 2008 14:35:29 -0400 (EDT)
"Scott R. Ehrlich" <scott@...> wrote: > On Sun, 4 May 2008, Tom Metro wrote: > > > Scott R. Ehrlich wrote: > >> I just found an article comparing Ubuntu Linux (7.04) to Vista...> > > Link? > > > > Sorry - > http://www.informationweek.com/news/software/linux/showArticle.jhtml?articleID=199201179&pgno=7&queryText=&isPrev= > > or > > http://tinyurl.com/5wepbp front end to tar. "One problem is that it doesn't seem possible to filter files to be backed up; it's everything in the source directory or nothing. Also, each backup set is complete; the program doesn't have an explicit option to perform incremental backups. (I also looked at the Keep Backup system, which had a similar set of options but also many of the same limitations.)" He does not mention that tar, rsync, and other command line tools have advanced filtering capabilities. He also fails to mention other backup solutions on Linux. -- -- Jerry Feldman <gaf@...> Boston Linux and Unix PGP key id: 537C5846 PGP Key fingerprint: 3D1B 8377 A3C0 A5F2 ECBB CA3B 4607 4319 537C 5846 _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Dan Ritter-2
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On Sun, May 04, 2008 at 11:10:14AM -0700, Kristian Erik Hermansen wrote:
> I'll just wait for ZFS on Linux, but it's nice to know ext3cow is an > option too :-) It seems likely that you'll be waiting a long time. ZFS is under the CDDL, which is highly non-GPL compatible, and Sun's patents suggest that they don't want anyone reverse-engineering it, either. Nor do I think Sun management has much of a soft spot for Linux these days... -dsr- -- http://tao.merseine.nu/~dsr/eula.html is hereby incorporated by reference. "Someone is wrong on the Internet." - Randall Munroe -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Kristian Erik Hermansen
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On Sun, May 4, 2008 at 3:58 PM, Dan Ritter <dsr@...> wrote:
> It seems likely that you'll be waiting a long time. ZFS is under > the CDDL, which is highly non-GPL compatible, and Sun's patents > suggest that they don't want anyone reverse-engineering it, > either. Nor do I think Sun management has much of a soft spot > for Linux these days... Perhaps ;-/ You can already use ZFS on Linux via FUSE, but I would hope that someone will want it bad enough to reimplement it. You can get around the reversing-to-implementation problem using the Chinese Wall methodology, so I don't see why that would be a problem... -- Kristian Erik Hermansen -- "When you share your joys you double them; when you share your sorrows you halve them." -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Jarod Wilson
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On Sun, 2008-05-04 at 16:08 -0700, Kristian Erik Hermansen wrote:
> On Sun, May 4, 2008 at 3:58 PM, Dan Ritter <dsr@...> wrote: > > It seems likely that you'll be waiting a long time. ZFS is under > > the CDDL, which is highly non-GPL compatible, and Sun's patents > > suggest that they don't want anyone reverse-engineering it, > > either. Nor do I think Sun management has much of a soft spot > > for Linux these days... > > Perhaps ;-/ You can already use ZFS on Linux via FUSE, but I would > hope that someone will want it bad enough to reimplement it. You can > get around the reversing-to-implementation problem using the Chinese > Wall methodology, so I don't see why that would be a problem... btrfs 0.14 released just a bit ago... http://kerneltrap.org/Linux/Btrfs_0.14_Managing_Multiple_Devices -- Jarod Wilson jarod@... -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: ext3cow FS?
by Kristian Erik Hermansen
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On Sun, May 4, 2008 at 5:17 PM, Jarod Wilson <jarod@...> wrote:
> btrfs 0.14 released just a bit ago... > > http://kerneltrap.org/Linux/Btrfs_0.14_Managing_Multiple_Devices I forgot about btrfs! Very nice... -- Kristian Erik Hermansen -- "When you share your joys you double them; when you share your sorrows you halve them." -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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Re: Chinese Wall and software patents
by Tom Metro-12
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Kristian Erik Hermansen wrote:
> Dan Ritter <dsr@...> wrote: >> ...Sun's patents suggest that they don't want anyone reverse-engineering it... > > You can get around the reversing-to-implementation problem using the Chinese > Wall methodology... A "Chinese Wall" - making sure the implementors have never seen the original code - only helps you avoid copyright infringement. Like if you're a PC clone manufacturer and you want to create a BIOS compatible with IBM's. This technique does nothing for avoiding patent infringement. That's why software patents are so dangerous. You can do a completely independent implementation of an algorithm, have no knowledge that the algorithm was even thought of before, and still be in violation. Open source is particularly vulnerable to such claims as the source is readily available for claim holders to inspect looking for violations. To avoid patent infringement you're better off carefully studying the existing implementation and its patents, so you can engineer around the patents. -Tom -- Tom Metro Venture Logic, Newton, MA, USA "Enterprise solutions through open source." Professional Profile: http://tmetro.venturelogic.com/ -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. _______________________________________________ Discuss mailing list Discuss@... http://lists.blu.org/mailman/listinfo/discuss |
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