Date: Thu, 14 Mar 2002 13:23:38 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Christoph Hellwig <hch@caldera.de> Cc: AQUAMAN <yoatl@yahoo.com>, freebsd-fs@FreeBSD.ORG Subject: Re: filesystems compatibility Message-ID: <3C9114DA.5A2D0591@mindspring.com> References: <20020312185747.98993.qmail@web13305.mail.yahoo.com> <3C8E72A3.6E9CBC6F@mindspring.com> <20020314183219.A28415@caldera.de>
next in thread | previous in thread | raw e-mail | index | archive | help
Christoph Hellwig wrote: > On Tue, Mar 12, 2002 at 01:26:59PM -0800, Terry Lambert wrote: > > It's really hard to answer these kinds of questions exhaustively, > > since Linux has the bad habit of changing things about the on > > disk layout of FS data, and not changing the name of the FS; > > there are at least six incompatible hacks on EXT2FS since the > > first EXT2FS, and knowing which one you have is an exercise in > > detective work. > > [snip] > > Terry, > > could you _please_ check the facts before you are going to tell the > world fs myth over and over? > > Unlike FFS/UFS which has at least a dozen incompatible derivates ext2 > was designed with extensibility in mind. If you would care to actually > look at the ext2 superblock definition you would notice two things: > > 1) a revision level (s_rev_level) > 2) 3 feature flags (s_feature_compat, s_feature_incompat, > s_feature_ro_compat) I am aware of this. Perhaps, since you are knowledgeable in the Linux EXT2FS area, you can answer the rest of the original question, now that I've narrowed the answer to "some version of EXT2FS"? -- What is the highest revision level, and what are the maximum feature flags that one can use interoperably between versions of RedHat, FreeBSD, Debian, and Mandrake? > Sparse superblocks is a feature introduced in Linux 2.2 and thus > supported by all Linux distributions having 2.2 or newer kernels > (including Debian potatoe/woody!), which was also backported to 2.0 > and included in 2.0.39. Sorry; he did not specify the version of Debian he was using, or the version of RedHat or Mandrake, or even FreeBSD for that matter). I'm guessing it will have to be "lowest revision" and "no feature flags". PS: Different versions of FFS have different magic numbers; the original number was Kirk's birthday. PPS: I'm more of an FFS maven than an EXT2FS maven; so I would be more likely to be able to tell you about FFS interoperability between systems. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3C9114DA.5A2D0591>