Quick Filesystem Reference Matrix

[ross-spencer]

Happened to be referencing this table again today. It's a nice matrix showing which file systems have support for XATTRS, it can be sorted, and shows ~30?!

• https://en.wikipedia.org/wiki/Comparison_of_file_systems#Metadata

I think the main ones looked at for AHAlodeck have been:

• ZFS
• EXT
• BTRFS
• NTFS (partially)

Could be something to do down the line to crib this table for the AHAlodeck docs, maybe including dates that also help folks to discover the most recent implementations. (Also compatibilities)

[pjotrek-b]

Thanks for putting this here.
Indeed, I'm quite happy to see that so many filesystems support the idea of "key/value" information in the filesystem.

I'd add "HPFS" and "APFS" - which I add in theory, because all I know about their xattr/resource-fork behavior is from reading and what people told me who use MacOS.

And "F2FS" as possible candidate to support xattrs on Android.

[pjotrek-b]

Found this, as I was looking for "where I wrote down the byte limits of xattrs per filesystem".
Here we go (again):

Related discussion #14, contain tech details about xattrs in certain filesystems:
The Quest of Finding Out: "How to find out the actual byte-limit of xattrs on /that/ filesystem?"
#14

filesystem	xattr y/n	bit-proof	size limits	remark
ZFS	✔️	✔️	up to ca. 64 kB per key/value pair; unlimited keys	main test+production candidate. "just works"
EXT4	✔️	✔️	up to almost 4096 Byte for all key/value metadata	tight, but works for most "vitally necessary or popular" audio,video,image,document metadata, commonly "embedded"
HFS, APFS	✔️ ❓	✔️ ❓	unlimited (according to docs)	not tested personally /yet/
FAT32 (vfat)	🚫	--	--	Rumor has it, that metadata "can somehow be added", but it's not lib-code compatible with POSIX-style xattrs
NTFS	✅	?	?	NTFS calls xattr-like metadata capabilities "Alternate Data Streams"
F2FS	✔️	❓	~4096 Byte	seems similar to ext4, but haven't tested it /yet/
exFAT	🚫	--	--	Although being a "young" filesystem, they didn't consider xattrs "worth it".
BTRFS	✔️	✔️	~64 kB?, but unclear if limit in number of keys?	Tested a little bit, but ran into "out of diskspace (for xattrs) errors with xattrs working on ZFS