On 2014-12-22 15:04, Richard Sharpe wrote: > On Mon, Dec 22, 2014 at 10:09 AM, Austin S Hemmelgarn > wrote: >> On 2014-12-22 12:27, Richard Sharpe wrote: >>> >>> On Mon, Dec 22, 2014 at 6:28 AM, Austin S Hemmelgarn >>> wrote: >>>> >>>> On 2014-12-19 21:07, Richard Sharpe wrote: >>>>> >>>>> >>>>> Hi folks, >>>>> >>>>> I need a Linux file system that supports XATTRs up to 64K. >>>>> >>>>> Can BTRFS support that or is XFS the only Linux file system with such >>>>> support? >>>>> >>>> At the moment, BTRFS is limited to xattrs that fit inline in the metadata >>>> nodes (so ~3900 bytes for a 4k leafsize). >>>> >>>> XFS, however, isn't the only Linux filesystem that supports xattrs that >>>> size. Assuming that you are using a recent kernel, you can also use such >>>> xattrs on at least: >>>> * XFS >>>> * JFS >>>> * ext4 >>>> * reiserfs (I think, not 100% certain about this one though) >>>> * OCFS2 (even though it is technically a cluster fs, it can be run >>>> single >>>> node without the clustering) >>>> * ZFS (IIRC, ZFS supports unlimited xattr size) >>>> * NTFS (no limit on xattr size, though you should use NTFS-3G instead >>>> of >>>> the in-kernel driver) >>>> * SquashFS (read-only) >>>> * HFS+ (Also no limit on xattr size) >>>> Of these, I'd personally suggest using XFS unless you need to be able to >>>> shrink the filesystem, in which case I'd suggest ext4. >>> >>> >>> Thanks for the info. I hadn't realized that ext4 had lifted the >>> restriction. >>> >> Yeah, it would be nice if there was more clarity in the documentation. >> >> Personally, I'd love to see unlimited length xattr's like NTFS and HFS+ do, >> as that would greatly improve interoperability (both Windows and OS X use >> xattrs, although they call them 'alternative data streams' and 'forks' >> respectively), and provide a higher likelihood that xattrs would start >> getting used more. > > Well, there is a big difference in the semantics of Alternate Data > Streams (ADSs) and XATTRs. > > For example, you can seek on an ADS and read at any offset. You cannot > do that on an XATTR (at least, not with the semantics provided by the > UNIX interface.) > I'm not trying to say the semantics are identical, just that the functionality is pretty similar. A better way to put it would be that xattrs are an extremely limited form of ADS/Forks.