On Wed, 10 Sep 2008 13:30:45 +0200, Tobias Oetiker wrote: > What happens if the disk hosting an external journal of a filesytem > running with data=journal goes bust. Probably the same as if the journal was on the same disk, going bust. :-) Or rather :-( as this can indeed get pretty ugly. With ext3 you can always fall back to mounting as ext2 and at least try to recover as much as possible. > Recently we added an SSD to our setup and have moved all the journals to > this ssd. This has dramatically improved performance and especially > reduced the interdependence between performance of different partitions > hosted on the same RAID. That is one of the great SSD uses, yes. > http://insights.oetiker.ch/linux/external-journal-on-ssd.html Very interesting, thanks! I was planning to do the same but waiting for the Intel SSDs to come to market or the large OZCs to come down in price, whatever happened first.. > I realy like the performance of this new setup, but I am not all that sure > about the data security aspects of it. Especially after reading > > http://www.cs.wisc.edu/adsl/Publications/sfa-dsn05.pdf > > which suggests that damaged journals are the worst that can happen to > ext3. True, a borked journal is bad but with the SSD you should actually have *less* chance of corruption (of the type mentioned in the paper), since the wear-leveling should keep the journal blocks alive without the file system/block layer noticing. At least in theory.. :-D You may also find this interesting: http://labs.google.com/papers/disk_failures.html Holger _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
