.\" $Header: /cvsroot/myrescue/doc/myrescue.1,v 1.5 2004/02/11 16:14:40 kristofk Exp $.TH MYRESCUE "1" "December 2002" "myrescue 0.9.0" "User Commands".SH NAMEmyrescue \- Harddisc Rescue.SH SYNOPSIS.B myrescue .RB [ -b.IR block-size ].RB [ -B.IR bitmap-file ].RB [ -S ].RB [ -r.IR retry-count ].RB [ -s.IR start-block ].RB [ -e.IR end-block ].I input-file.I output-file.SH DESCRIPTIONmyrescue is a program to rescue the still-readable data from adamaged harddisk. It is similiar in purpose to dd_rescue, but ittries to quickly get out of damaged areas to first handle the notyet damaged part of the disk and return later..PPThe program tries to copy the device blockwise to a file andkeeps a table ("block bitmap") noting whether a block has beensuccessfully copied, not yet handled or has had errors. This blockbitmap can be used in successive runs to concentrate on the not yetrescued blocks..PPThe program has a special skip mode to handle read errors. Usuallyharddisk surface defects cover more than just one block and continuousreading in defect areas can damage the surface, the heads and (bypermanent recalibration) the drive mechanics. If this happens, thechances of rescuing the remaining undamaged data drop dramatically. Soin skip mode, myrescue tries to get out of damaged areas quickly byexponentially increasing the stepsize. The skipped blocks are markedas unhandled in the block bitmap and can be retried later..PPFinally, the program has an option to multiply try to read ablock before considering it damaged..SH NOTE.B This tools is no replacement for a professional data recovery service!If you do have the latter option, don't even think of using .BR myrescue ,as it may further damage your disk. This tool isprovided only for the case that you are absolutely desperate anddefinitely cannot afford a professional data recovery. Or in caseyou know what you are doing, e.g. if you know that it is the agingof the magnetisation layer that is causing your problem..PPIn any case do not expect too much. While complete restores have beenwitnessed, you should not take them for granted. A better attitude isto consider your data lost and be glad for any survivors that turn up..PPThe usual GPL disclaimer applies. Especially the NON-WARRANTY OFFITNESS FOR A PARTICULAR PURPOSE. Don't blame (or sue) me if itfails to recover or further damages your data..PPAnd a final word you probably don't want to hear in this situation:For the future consider a routinely backup to avoid a "next time"..SH OPTIONS.TP.BI -b " block-size"The size of the blocks (in bytes). Set this to yourharddiscs error detection/correction unit size. Usuallythis is 4096, which happens to be the default..TP.BI -B " bitmap-file"The file containing the status table of all blocks. Nice (orfrightening...) to view with hexdump. 01 means OK; 00 means not yetdone; negative values mean the number of failed read attempts. If notgiven, defaults to.IB output-file .bitmap.TP.B -SActivate skip mode: When encountering errors increase the stepsizeexponentially until a readable block is found..TP.BI -r " retry-count"The number of times to read a block before it is declaredbad for this run. (You can still retry it on the next run.) Default: 1.TP.BI -s " start-block"The number of the block to start with. Default: 0.TP.BI -e " end-block"The number of the block, where reading stops (not included!).Default: size of .I input-filedivided by .IR block-size . .TP.BR -h ", " -?Display usage information..SH RECOMMENDED PROCEDURE.IP \(buMake sure you have sufficient disk space to copy the wholepartition (not just the used ammount of data) to plus somespace for the block bitmap (1 byte per block)..IP \(buDetermine the hardware block size (CRC/ECC unit) of yourharddisk. This may be found out from hdparm, some entries in/proc/ide/hd? or on the web. I have not yet checked whetherthis is possible with an ioctl. If you have, please let meknow..IP \(buStart a skip mode run with one retry per block to first copythe undamaged area..IP \(buStart a normal run with one retry per block to copy theremaining skipped blocks..IP \(buRepeat until the number of errors seems to have converged.Try waiting a couple of hours between the retries..IP \(buRepeat this with higher retry counts and wait for convergence..IP \(buMake a copy of the rescued data and run fsck on it..IP \(buMount the filesystem (if copied to a file: via loopback) and checkyour data. If directory information has been destroyed, fsck movesunidentifiable file fragments to lost+found, so you should also checkthis location..PPIt may help to try reading non-defect areas in between to allow thedrive to recalibrate..PPThe developers are glad to hear about your experiences. Please postthem to the.B Experiencesforum on the Sourceforge Project page. Thank you!.SH KNOWN BUGSThe handling of the .I bitmap-file currently relies on the filesystem semantics, that when.BR lseek (2)ing beyond the end of file and then writing, the space in between isfilled with zero-bytes..SH AUTHORSKristof Koehler <kristofk@users.sourceforge.net>,Peter Schlaile <schlaile@users.sourceforge.net>.SH SEE ALSO.BR dd (1),.BR dd_rescue "(no manpage?)".PPhttp://www.google.de/search?q=data+recovery.PPhttp://myrescue.sourceforge.net/