Savedir on FAT anyone?

[jamesbond]

There is a thread elsewhere that talks about "savedir" (aka save folder) for puppy. The last few posts discusses about doing that on NTFS; and this genereted quite a bit of heat.

Why not take it further? Why not having savedir on FAT partitions? Well why not!

Next release of Fatdog (whenever it will be) will support savedir on FAT. No, this is not a joke As an added bonus it will also enable Fatdog to use savedir on CIFS (Fatdog already supports savefile on CIFS today). Enjoy savedir on the lowest common denominator of a filesystem with full support for permissions, file modes, device nodes and FIFOs. In fact, just like your regular ole' ext2 filesystem (sans the reliability ).

Ingredients? posixovl.

[unicorn316386]

Nice idea. I have recent slacko on dual-boot with Freedos in FAT32, only option is savefile but works ok and I'm used to it.

[gcmartin]

Since there are various versions that are commonly referred to as "FAT" can it be assumed that the upcoming distro's solution will work on FAT32 and VFAT?

A solution extension of this sort expands the number of manners in which a FATDOG system's persistence can reside. I see this as your intent ... a good one.

[jamesbond]

Since there are various versions that are commonly referred to as "FAT" can it be assumed that the upcoming distro's solution will work on FAT32 and VFAT?

Correct.

A solution extension of this sort expands the number of manners in which a FATDOG system's persistence can reside. I see this as your intent ... a good one.

Actually released versions of Fatdog can already use a savedir on FAT, even today. Well, Fatdog can use a savedir (and savefile) on *any* filesystem that it can read and write, including FAT, NTFS, XFS, F2FS, CIFS, etc. I just don't explicitly advertise it because it's experimental and not well-tested; so if you want to use it you'd better be aware of the possible consequences. For one example, if you try to use savedir on a non-POSIX filesystem, you will find that it works less than satisfactorily.

Today I just added posixovl so that FAT and CIFS behaves a little bit more POSIX-y; but this comes with a very _heavy_ price --> the device cannot be unmounted cleanly at boot. This is less of a problem with CIFS but a *big* problem for FAT, brittle as it already is. I personally would not recommend it for every day use (I said the same thing for savedir on NTFS - this is even truer for FAT); and if you do, make sure you fsck the filesystem at every boot.

But as I said in my blog post - "But if you're happy to play with fire, then - yeah, why not?" Yeah, why not? That's why this post is in the "Cutting Edge" section. Just be careful of not cutting your own finger with the sharp edge while playing

[musher0]

Hi, JamesBond.

Have you ever considered UDF for this? Apparently, it can preserve extN file
properties. Just a thought.

BFN.

[gcmartin]

In past discussions on filesystem for save sessions, I have never suggested to ignore dangers, while many have express concerns.

@JamesBond is helping all in articulating pitfalls and gives excellent advice of step to minimize potential problems in use of non-Posix filesystems.

Heed that advice!

Thanks @JamesBond and @Kirk for FATDOG and what it has done for 64bit processing in Puppyland.

[jamesbond]

@gcmartin - you're welcome.

Hi, JamesBond.

Have you ever considered UDF for this? Apparently, it can preserve extN file
properties. Just a thought.

BFN.

It depends on what the kind of supported you're thinking about.If you're thinking of using UDF on some sort of device (e.g. flash drive) for data sharing between different OS, then it works already, either using savefile or savedir (if you use savedir please use the RAM layer; direct write won't work due to aufs limitation). From the grapevine I heard that (but which I haven't tested myself) UDF is actually the best way to share data between different OSes as it is well supported by Windows (XP and newer), Mac, and of course our favorite OS.

A little annoying details, though: there is no bootloader that can support booting from UDF. If you use r/w UDF on a DVD, then that DVD is not bootable. If you use a single UDF partition on that flash drive, then it is not bootable. For flash drive the solution is simple - just create two partitions, one FAT (or ext3/4 or whatever) that is bootable, and use UDF for the 2nd partition. For DVD the situation is not so simple; you will need to carry two DVDs (one for booting, another for savefile/savedir); or one flash drive (for booting) and one DVD. This has nothing to do with Fatdog, this is purely because nobody bothers to write an open source bootloader for UDF (and there is no specification for that too, which perhaps explain the reluctance).

PS: r/w UDF on a DVD is *reeeeeeeeally slow*.

___________________________

If you want to use your DVD+RW as a floppy disc, just do this:
a) insert blank disc to your optical drive
b) from terminal: mkudffs --vid="MY DISC" --media-type=dvdrw --utf8 /dev/sr0
(change "dvdrw" to "dvd" if you use anything other than DVD+RW)
c) go play skiing or something. Seriously, this takes ages.
d) when it's done, mount it just like any other r/w media
e) dump some files, then unmount it. You may want to boil some coffee or fetch some wines from your cellar.
f) when done, eject; ready for use, repeat step d,e,f ad infinitum.