tkoppel@isis.UUCP (06/08/87)
Earlier this evening, when running a "chkdsk b:*.*", I got the
wonderful and mysterious message:
1 lost cluster found in 1 chain --
Convert lost chains to files?
What does this mean? The chkdsk went on to say that the disk itself
had all sorts of file system errors .. Can one recover from this
"lost cluster condition" without reformatting the disk?
Many thanks..
--
Ted Koppel == CARL - Colorado Alliance of Research Libraries ==
303-750-9142 !hao!isis!tkoppel CompuServe: 71460,1572darrylo@hpsrlc.UUCP (06/10/87)
In comp.sys.ibm.pc, tkoppel@isis.UUCP (Ted Koppel) writes: > Earlier this evening, when running a "chkdsk b:*.*", I got the > wonderful and mysterious message: > 1 lost cluster found in 1 chain -- > Convert lost chains to files? > > What does this mean? The chkdsk went on to say that the disk itself > had all sorts of file system errors .. Can one recover from this > "lost cluster condition" without reformatting the disk? > > Many thanks.. > > -- > Ted Koppel == CARL - Colorado Alliance of Research Libraries == > 303-750-9142 !hao!isis!tkoppel CompuServe: 71460,1572 > ---------- The answer is a "qualified yes". The default action for chkdsk is to report but not fix errors (I'm not sure if this is true for *ALL* errors -- very severe ones *may* get fixed). To get chkdsk to "fix" these errors, you need to specify the "/f" switch: "chkdsk B:*.* /f". This time, answer "y" to the question, "Convert lost chains to files?", and chkdsk will convert any lost chains that it finds into files (why it asks this question when the "/f" switch is not specified is beyond me). ***** WARNING! WARNING! WARNING! ***** NOTE: IF THE DISK (FLOPPY OR HARD DISK) IS *REALLY* CORRUPTED, RUNNING CHKDSK WILL NOT DO ANY GOOD AND MAY EVEN TURN THE FILE SYSTEM INTO EVEN MORE GARBAGE. Chkdsk tries to fix the disk as best as it can. However, something trashed your disk (like a crashing program, a program that terminated without cleaning up its files, a TSR conflict, etc.), and this something may have also trashed some or all of the files on the disk. This can range from a file whose contents is complete garbage to a file where only ONE byte has changed. After chkdsk has "fixed" the disk, examine the files which were created from the lost chain(s). These are placed in the root directory of the disk, and are of the form "FILExxxx.CHK", where "xxxx" is a number. -- Darryl Okahata hplabs!hpcea!hpsrla!darrylo CompuServe: 75206,3074 Disclaimer: the above is the author's personal opinion and is not the opinion or policy of his employer or of the little green men that have been following him all day.
neuhaus@hplabsb.UUCP (06/10/87)
Do a chkdsk b: /f. This will convert the lost clusters to *.chk files which you just delete. Lost clusters are parts of files who forgot who them belong to. They are typically created by programs that don't close files before terminating (or got hung and you rebooted the system.)
cramer@kontron.UUCP (Clayton Cramer) (06/10/87)
> Earlier this evening, when running a "chkdsk b:*.*", I got the > wonderful and mysterious message: > 1 lost cluster found in 1 chain -- > Convert lost chains to files? > > What does this mean? The chkdsk went on to say that the disk itself > had all sorts of file system errors .. Can one recover from this > "lost cluster condition" without reformatting the disk? > > Many thanks.. > > Ted Koppel == CARL - Colorado Alliance of Research Libraries == "Lost cluster" means that a cluster of sectors were allocated in the FAT (file allocation table), but not attached to any file in the directory. This is frequently the result of a program writing a file, then the system crashes before the file was closed. The directory is therefore out of date, but the FAT shows the cluster as allocated. Use the /F option on CHKDSK. This will ask you if you want to free the lost clusters, or turn them into files. If you turn them into files, they go in the root directory with names like "FILExxxx.CHK", and contain the contents of these clusters. I've never had any real use for trying to reconstruct files from these lost clusters. Before anyone flames PC-DOS for not keeping the directory up to date, remember that there is a trade-off between perfectly up to date file system, and performance. I wrote a file system for a telephone switch several years ago where the old file system trade-off had been on the side of performance -- the wrong choice for a system that had to come up automatically and lose no data. For a system like PC-DOS, Microsoft chose performance, and I can't claim that this was automatically a mistake. (Sure would be nice to have a flag you could set to make the trade-off at run-time...) Clayton E. Cramer
timothym@tekigm2.UUCP (06/10/87)
In short, yes.
You can recover lost chains and clusters by the following method:
CHKDSK X: /f
Then if you want to save the chains as files, answer yes to the prompt you're
given. Otherwise CHKDSK will erase the chain, and free up the disk space.
--
Tim Margeson (206)253-5240
PO Box 3500 d/s C1-937 @@ 'Who said that?'
Vancouver, WA. 98668
{amd..hplabs}cae780!tektronix!tekigm2!timothym (this changes daily)perry@omepd.UUCP (06/10/87)
In article <1855@isis.UUCP> tkoppel@isis.UUCP (Ted Koppel) writes: >Earlier this evening, when running a "chkdsk b:*.*", I got the >wonderful and mysterious message: > 1 lost cluster found in 1 chain -- > Convert lost chains to files? > >What does this mean? The chkdsk went on to say that the disk itself >had all sorts of file system errors .. Can one recover from this >"lost cluster condition" without reformatting the disk? A *cluster* is the logical storage unit on a disk; it is one or more disk blocks (512bytes each). A *lost cluster* is a cluster that is marked *used* (i.e., is not free space) but that does NOT belong to any file (or directory) on the disk. That shouldn't happen but sometimes it does, especially when your machine crashes during a write operation. Clusters are *chained* on your disk (in the FAT, to be exact), with a directory entry pointing to the first block. Thus, if the directory entry gets trashed all clusters in that *chain* become lost. CHKDSK gives you the option to recover these *lost clusters*. Call CHKDSK /F (for FIX it) and answer YES to the question above. CHKDSK will create files FILEnnnn.CHK in the root directory of the disk that contain the lost clusters, one for each chain. You can then examine these files with an editor or dumper or whatever, and use them as usual (or delete them to free the space). This does NOT destroy anything on your disk (the damage has already been done :-) and doesn't touch files that have no problems. See your DOS manual (CHKDSK command) for details. Oh, one thing that probably confused you: if you call CHKDSK *without* the "/F" argument, it still asks you the conversion question, just to tell you then that it didn't do anything. Can't make it too clear here now, can we? ------------------------------------------------------------------------ << Perry The Cynic >> =>> perry@inteloa.intel.com <<= ...!tektronix!ogcvax!omepd!inteloa!perry (Peter Kiehtreiber) ...!verdix!omepd!inteloa!perry
stevev@uoregon.UUCP (06/11/87)
In article <1855@isis.UUCP> tkoppel@isis.UUCP (Ted Koppel) writes: >Earlier this evening, when running a "chkdsk b:*.*", I got the >wonderful and mysterious message: > 1 lost cluster found in 1 chain -- > Convert lost chains to files? > >What does this mean? The chkdsk went on to say that the disk itself >had all sorts of file system errors .. Can one recover from this >"lost cluster condition" without reformatting the disk? A file on a disk is essentially a chain of clusters, and a cluster is the smallest unit of disk space that can be allocated to a file. Sometimes a chain of clusters will get unhooked from a directory entry (often if a file is opened, written to, but not closed properly, i. e. the machine crashes before the file is closed). When that happens the clusters are still marked as allocated but don't correspond to any file on the disk. CHKDSK will find these lost chains and give you the option turning them back into files that you can either delete or possibly recover lost information from the file. Recovered files are placed in the root directory on the disk with names FILEnnnn.CHK where nnnn starts with 0000. You must run CHKDSK with the /F switch to have it recover lost cluster chains. -- Steve VanDevender uoregon!drizzle!stevev stevev@oregon1.BITNET "Bipedalism--an unrecognized disease affecting over 99% of the population. Symptoms include lack of traffic sense, slow rate of travel, and the classic, easily recognized behavior known as walking."
jmc@ptsfa.UUCP (Jerry Carlin) (06/11/87)
In article <58200001@hplabsb.UUCP> neuhaus@hplabsb.UUCP (Peter Neuhaus) writes: >Lost clusters are parts of files who forgot who them belong to. They are >typically created by programs that don't close files before terminating... Is this true of MS-DOS backup? I've had to chkdsk my backup diskettes ever since I found one day that 1/3 of my diskettes were munged (I noticed that the backup took too many diskettes). -- voice: (415) 823-2441 uucp: {ihnp4,lll-crg,ames,qantel,pyramid}!ptsfa!jmc CompuServe: 73075,1133 GEnie: jerrycarlin Where am I? In the village. Whose side are you on? That would be telling.
jpn@teddy.UUCP (John P. Nelson) (06/15/87)
>I hope that this question doesn't sounds dumb, but by doing a CHKDSK /F, >is there any possibility of loosing/deleting/erasing a file? From what >I have heard, if the bad cluster is in one of the files, when you do a >CHKDSK /F, it will erase the file. Is this information incorrect? If so, >then is it possible for ANY file on the drive to be erased? This isn't QUITE true. CHKDSK is simply pointing out a problem that ALREADY exists, which is that there is no file which contains the lost clusters! Also, CHKDSK is giving you a chance to put those lost clusters BACK into files, so that you can examine them! As long as "lost clusters" is the ONLY problem which CHKDSK reports, then there is no way that CHKDSK can do further damage if used with the /F flag. On the other hand, if there is significant filesystem damage (a botched directory, for instance), then CHKDSK may not be able to do much, and can possibly make the situation worse. In this case, always be sure to backup your disk before attempting repair!
davidr@hplsla.UUCP (06/15/87)
My personal experience does not leave me enamored with CHKDSK. About one third of the time I have resorted to using /F because of errors reported by CHKDSK I have lost a lot of files. It seems to be especially if CHKDSK reported clusters held in duplicate (I do not remember the exact wording of the error message, and have no way of intentially creating such, but it was something to the effect of two files claiming use of the same cluster). In saying that I lost files does not mean that they were erased, but that they became garbage as CHKDSK tried to straighten out which clusters belonged to which file in which order. A real nightmare. I only wish I could figure out what causes such a mess-up with the FAT to create this "dual ownership". Otherwise, if CHKDSK reports lost clusters, the /F has simply created a few garbage FILE????.CHK files at the root level from which nothing useful has ever been recovered (in my case), but has restored some usable disc space upon their deletion. ******************************************************************************* -David M. Reed ------ hpLSID ------ hplsla!davidr ------ 335-2460 ------ msUN5- *******************************************************************************