T L wrote:> Hi list,
>
> Does Samba support large extended attributes? By this I'm referring to
> attributes that are alternate streams attached to a file.
>
> http://msdn.microsoft.com/en-us/library/aa364404%28v=vs.85%29.aspx
>
> Seeing a problem when the referenced stream points to large files
(sometimes
> 3M+).
>
> Thanks for the help,
> - T
---
I'm guessing it depends on what file system you are using and how big
the extended attributes are that it supports. XFS, I think is limited
to something like 64k/attr (but don't quote me on that!) of extended
attributes; I've no idea if there is a combined limit.
Maybe another file system supports larger.
There's also a samba option to store extended attributes in a file
'somewhere' ...
it's a vfs module...
IT says 'experimental''...but the vfs_streams_depot, might work
There are also modules 'vss_streams_xattr, to store them in extended
attributes,
and there's a vfs_xattr_tdb, which can store EA's in a TDB,
I don't know if the modules 'stack'...but if the vfs_streams_depot
doesn't
work, then if you used the vfs_xattr_tdb, and stored all your attr's in
a TDB (a database
file), then the vfs_streams_xattr to store streams in xattrs ***might***
store
the streams in the tdb...
But 3M for an alternate data stream is pretty 'huge'....compared to
normal purposes -- generally to hold things like the file's source
(internet or not, so it can give you a message about it possibly being
'unsafe' to open)....little bits and pieces.
It's not 'normally', AFAIK, used for general purpose data
storage...i.e.
3M of data should
probably be stored in a normal file, not a 'resource-fork/data stream,
as those are more for
metadata.
Here's what the manpage for xfs-attr says about 'extended attrs':
Extended attributes implement the ability for a user to attach
name:value pairs to objects within the XFS filesystem.
This document describes the attr command, which is mostly
compatible
with the IRIX command of the same name. It is thus aimed
specifically
at users of the XFS filesystem - for filesystem independent
extended
attribute manipulation, consult the getfattr(1) and
setfattr(1) docu?
mentation.
Extended attributes can be used to store meta-information
about the
file. For example "character-set=kanji" could tell a
document
browser
to use the Kanji character set when displaying that
document and
"thumbnail=..." could provide a reduced resolution overview
of
a high
resolution graphic image.
In the XFS filesystem, the names can be up to 256 bytes in
length, ter?
minated by the first 0 byte. The intent is that they be
printable
ASCII (or other character set) names for the attribute. The
values can
be up to 64KB of arbitrary binary data.
(of course you 'could' have 3M of metadata, but it would be unusual...)
Do you really have 3M of name=attribute strings?
Good luck!...