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Amiga computer related discussion => Amiga Software Issues and Discussion => Topic started by: BinoX on July 26, 2007, 05:18:21 PM
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Looking through a bunch of stuff I got off a friend the other day and I noticed a disk with PFS3 on it...
I was wondering what features PFS3 has... And how does it compare to SFS? (or how doesn't it I suppose)
Thanks,
Luke
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If you got a disk, was it a CD? If so, it will have a manual on it ;)
I don't know the features of SFS, but PFS3 includes the following:
The ability to retrieve up to the last 900 files deleted on the partition.
The ability to have long filenames (I have mine set to 85 characters, but it can go longer, but I can't remember how much).
Supposedly safe writing to disk (it doesn't write the file to disk until the whole file is ready to go, or something, so that if you get a power cut, you don't lose the original file).
A MUCH faster disk drive reading/writing/deleting capability. This alone, is worth the price I paid originally.
I'm sure there is more, I just can't remember :pint: :pint:
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it doesn't write the file to disk until the whole file is ready to go, or something, so that if you get a power cut, you don't lose the original file
It's called soft updates (http://en.wikipedia.org/wiki/Soft_updates), which is based on concept of atomic commit (http://en.wikipedia.org/wiki/Atomic_commit).
Basically it does write to disk right away, but it does it in a way that the filesystem logical structure cannot get corrupted even if power is lost. The final single write replaces the previous "snapshot" of the state of the filesystem with a new one. If power is lost before the final write can be made, the filesystem automagically rolls back to previous state.
Simple (and simplified) way to visualise this is think about filesystem metadata as a tree: Trunk is the root directory. Branches are the subdirectories, leaves are the files. When changes occur to this tree, PFS3 updates clone of the tree structure in memory. When PFS3 does the "commit" it writes the file structure to disk in reverse order (from top down) [actually it only writes the changed parts, but it uses free blocks, it doesn't modify the original tree at all]. The final write "plants" the new tree, replacing the old one. If the write was successful, the storage held by the now obsoleted old tree parts are released for future use.
This is different from filesystem journaling (http://en.wikipedia.org/wiki/Journaling_file_system) SFS has.
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Ah, I see... That kinda makes sense..
Which one would you recommend running on a standard user desktop/3d games/whdload machine? (PFS or SFS?)
(btw.. just for the info.. My PFS3 is actually a PFS2 CD with a PFS3 upgrade disk)
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BinoX wrote:
Ah, I see... That kinda makes sense..
Which one would you recommend running on a standard user desktop/3d games/whdload machine? (PFS or SFS?)
(btw.. just for the info.. My PFS3 is actually a PFS2 CD with a PFS3 upgrade disk)
PFS of course cause is lot faster than SFS
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I haven't made good enough tests, but for "real life use" SFS feels faster IMHO. And I think PFS only supports 512 blocksize, so if you handle lots of big files, you might want bigger blocksizes with SFS. But anyway, choosing between SFS and PFS3 is pretty much in your feelings :) They're both quite similar with features. Most notable differences are that PFS3 has better repairing tools, but SFS is free.
I have both PFS3 and SFS partitions on Amiga(s) and on Pegasos. Both have worked fine. Usually I prefer SFS with 1024 bytes blocksize.
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I haven't made good enough tests, but for "real life use" SFS feels faster IMHO.
SFS is slower in real life use I have to say. SFS can get unbearably slow quite easily, say for example two applications writing to large files at the same time (they get blocks allocated in 1-2-1-2-1-2 fashion, resulting in massive worst-case-scenario fragmentation). That's quite stupid oversight from supposedly "smart" filesystem.
Last time I tested SFS it commited suicide after copying 20GB of data. Though I do admit that this is no indication of anything... ;-)
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Yeah, well.. fragmentation is a problem if you don't pay attention to it :) Better not to download several movies at once etc.. or at least download them to separate temp partition and copy them one at once to final destination. When you're aware it, it's pretty easy to keep partitions non fragmented. But booting, scanning and using non fragmented partition feels faster (IMHO).
I haven't had problems with big amounts of data. I've copied several times over 100G batches without problems over the years and systems.
Filesystem errors I've got similar amount on PFS3 and SFS.. not too often on either. Couple times over the 10 years... with PFS3 it usually can be fixed with pfsdoctor/diskvalid, but SFS needs reformatting. On Pegasos I haven't got any.. so it might have been because of kludgy & patched up a1200 too ;)
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I used to be a big fan of PFS (and before when it was called AFS), but eventually ditched it (last year) for SFS because PFS's support for long file names is terminally broken - using long file names can corrupt the current folder or even the whole disk. I haven't looked back since :-)
Oh, and yes, I did have PFS set-up correctly. There was a lot of discussion about how to do it correctly, from when it was still called AFS, and it worked fantastically well apart from the long file name problem.
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@ChrisH
I've never seen this long file name problem, and I do have tons of files with long names. In fact, this is the very first time I've ever heard of such problem.
Out of interest, how can I reproduce it?
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Hmm, I may have to get a couple of systems set up and try to run them side by side with the same configs and see what result I get.
Thanks for all the info guys :)
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Hmmm... I don't know if one problem on PFS was because of long filenames or what, but resulting corruption of current dir or whole disk sounds familiar.
I had reproduceable problem with wu-ftpd and PFS3 on my A1200. If I tried to write stuff with ftp to place which wasn't allowed to write, the PFS flipped completely and messed up dirs. Same didn't happen on SFS.
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ChrisH wrote:
I used to be a big fan of PFS (and before when it was called AFS), but eventually ditched it (last year) for SFS because PFS's support for long file names is terminally broken - using long file names can corrupt the current folder or even the whole disk. I haven't looked back since :-)
Oh, and yes, I did have PFS set-up correctly. There was a lot of discussion about how to do it correctly, from when it was still called AFS, and it worked fantastically well apart from the long file name problem.
what i "love" about your sentences, is the "absolute" way you post it!
what about to start with "on my system" for example? ;-)
ah... obviously PFS3 doesn't have any problems with long filenames
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pVC wrote:
Hmmm... I don't know if one problem on PFS was because of long filenames or what, but resulting corruption of current dir or whole disk sounds familiar.
I had reproduceable problem with wu-ftpd and PFS3 on my A1200. If I tried to write stuff with ftp to place which wasn't allowed to write, the PFS flipped completely and messed up dirs. Same didn't happen on SFS.
then i suggest to tell to the wu-ftp author, to fix his tool.
The same happened a couple years ago with Amigift also .... fixed then by his author ;-)
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ChrisH wrote:
I used to be a big fan of PFS (and before when it was called AFS), but eventually ditched it (last year) for SFS because PFS's support for long file names is terminally broken - using long file names can corrupt the current folder or even the whole disk. I haven't looked back since :-)
Oh, and yes, I did have PFS set-up correctly. There was a lot of discussion about how to do it correctly, from when it was still called AFS, and it worked fantastically well apart from the long file name problem.
Which version of PFS are you referring to? IFAIK AFS was many, many years ago then became PFS. Then there was PFS2 & the final version, PFS3. I use PFS 3 with filenames 85 characters long (not the maximum) & I haven't had any problems.
The occasions I have had trouble, I can't remember what it was (so long ago) PFSDoctor fixed it. I've been using PFS3 for around 8 years & my miggy is on 24/7 (it's an answerphone/fax!)
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When I still had my Amiga I used PFS3 too on all my partitions. I was messing with my system quite hard (completly custom installation) and was pleasured with the performance and stability the PFS gave me. Great file system.
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@Framiga
Any idea what exactly breaks it? There's wu-ftpd sources available, so anyone could fix it. But in any case, I feel quite suspicious to a filesystem, which can break like that with that many "standard" programs... (two commonly used programs are many for this kind fatal situation).
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unfortunately i'm not a coder. The only thing i can say is that was a Amigift core component (giftd the daemon IIRC) fault.
I could ask to the author as soon as i'll get him on the devel mailing list :-)
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My problem with long file names was definitely present in PFS 3 & PFS 2, and probably before then as well. It definitely occured under OS3.9.2 with Amithlon (with SCSI disks) & WinUAE (with direct access to IDE disks), and probably on my Blizzard PPC A1200 too.
The easiest way to cause the problem was to get AmiNetRadio to make some recordings to disk, which creates MP3s typically with ridiculously long filenames (depending on radio station). Unless I did it to RAM disk there would frequently be problems.
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@ChrisH
The easiest way to cause the problem was to get AmiNetRadio to make some recordings to disk, which creates MP3s typically with ridiculously long filenames (depending on radio station). Unless I did it to RAM disk there would frequently be problems.
I frequently do this, and I've never had a single problem.
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@ChrisH
have you ever set the filenamesize option during the format?
FILENAMESIZE=FNSIZE
FILENAMESIZE=107 here
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I also love PFS3 and use it on all my Amigas. Never a single byte lost due to it. Filenames set at 107. :-)
/me touches wood.
Where is directscsi support in SFS? Would make life a lot easier when trying to help people with +4GB problems.. :-)