-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 dan wrote: > just some more info, I ran the same directory creation test on a live > zfs filesystem on nexenta install. i got very similar performance > differences between ext3 and zfs as i did in vmware except it went from > 45seconds on ext3 to 15 seconds and from about 3 seconds to what felt > instant on zfs. i tried to make another observation here in reguards to > delayed writes. on ext3, when the directory script finished, the hard > disk light went out immediately(as expected) but the script on the zfs > volume kept the light on for about 4 seconds before it went out. i > repeated the script 3 times and got pretty much the same result each > time. zfs is definitely doing a delayed write and reporting faster > performance than reallity BUT i still wall-clock it at about 6 seconds > verses the 15 seconds for ext3. > > i would expect that this quote from sun's website is the explanation: > > *Blazing performance* > ZFS is based on a transactional object model that removes most of > the traditional constraints on the order of issuing I/Os, which > results in huge performance gains. > > there is the I/O caching. zfs caches checks of I/O and then reorders it > to do a large, more-sequential write. it is also a copy-on-write > filesystem which handles disk writes in a cache then reorder then write > method also. > > also. tale a look > http://www.opensolaris.org/jive/thread.jspa?threadID=11961&tstart=15 > <http://www.opensolaris.org/jive/thread.jspa?threadID=11961&tstart=15>
So basically your comparison is not 'fair' because in one case you are using write caching which will result in more lost data in some cases, compared to no write caching. I don't know what mount options are available for ext3, but I am pretty sure that there is an option to enable similar write caching. I would be really interested in seeing the commands you are executing to get these results (so other people can try and replicate them) and also the results on reiserfs (v3, I wouldn't use v4 on a production server, but perhaps v4 would also be interesting). PS, I've been a major fan of reiserfs for many years now, it seems to work really well for most of my needs, which primarily involve large maildir folders, backuppc, etc... I use it in most places as my preferred choice. Though I'd like to see how it compares in actual tests instead of just my 'gut feeling' that it is faster. Regards, Adam -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHx0OyGyoxogrTyiURAqObAJ0SOyXSwgGsOPOqXWxjkqYAOxJLUACgt50z D8jFpVNa4DOZ2hr08l+/4Jg= =tse8 -----END PGP SIGNATURE----- ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ BackupPC-users mailing list [email protected] List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
