I feel this is kind of over my head ... to boil it down: does it even make sense to run reiserfs inside a loopback partition?
Thanks, Joh On Wed, 21 Jan 2004 01:34:25 -0400 Peter Cordes <[EMAIL PROTECTED]> wrote: > On Tue, Jan 20, 2004 at 11:58:41PM -0500, Hubert Chan wrote: > > >>>>> "Johannes" == Johannes Graumann <[EMAIL PROTECTED]> writes: > > > > [...] > > > > Johannes> And on another note: in > > Johannes> > > http://www.mirrors.wiretapped.net/security/cryptography/filesystems/loop-aes/loop-AES.README > > Johannes> I read the following: "Don't use a journaling file system > > on Johannes> top of file backed loop device, unless underlying file > > system Johannes> is journaled and guarantees data=ordered or > > data=journal." Johannes> Can anybody comment on whether I can use > > reiserfs on top of my Johannes> loopback? > > > > The comment has nothing to do with whether or not your encrypted > > filesystem is a journaling filesystem with or without data=ordered. > > Actually, it does. > > > It > > has to do with using a file-backed loop device (versus > > partition-backed loop device), where the file is sitting on a > > journaling filesystem. If your loop device is a partition, or is > > file-based, but sits on top of a non-journaled filesystem > > Wait a second; I think this one doesn't belong in the list of things > that > will be correct. > > > or a journaled filesystem with data=ordered or > > journaled, then you can use any filesystem without problems. (Or, > > at least, you won't (shouldn't) run into any problems other than > > what you might run into if it were not on a loopback device.) > > > > Basically, if you don't have data=ordered, or data=journaled, any > > system crash could completely screw up your entire loopback, > > rendering it completely unusable. If you don't plan on having any > > system crashes or hard reboots, I think you can still run a loopback > > on top a non-data=ordered journaled filesystem fairly safely. > > No, the point is that journaling file systems depend on stuff being > written > to disk in the order they want, so if something goes wrong at _any_ > moment, they can pick up the pieces. ext3 with data=writeback, for > example, only bothers to strictly control the order of metadata. A > loopback to a file on such a filesystem will not preserve write > ordering, so a journaling filesystem on top of it will be making false > assumptions. Filesystem metadata (which needs to be ordered) is just > data on the loopback device. However, if the underlying filesystem > preserves data ordering, it can satisfy the requirements of the > journaling filesystem that's on top of it. > > I'm not sure if you need data=journal on the underlying filesystem > for > data=journal on the loopback filesystem to make sense, but I don't > think so. > > -- > #define X(x,y) x##y > Peter Cordes ; e-mail: X([EMAIL PROTECTED] , des.ca) > > "The gods confound the man who first found out how to distinguish the > hours! > Confound him, too, who in this place set up a sundial, to cut and > hack my day so wretchedly into small pieces!" -- Plautus, 200 BC > -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]