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74    
75     <body>
76     <div id="header">
77     <H2>Clonezilla-SysRescCD</H2>
78 sng 52 <H3>Offline Documentation: Data Recovery</H3>
79 sng 49 <div style="margin:0; padding: 3px; width: 980; position relative;">
80     <div style="position: absolute; left: 0px;"><H4>26/03/2010 - v 3.1.0</H4></div>
81     <div style="position: absolute; right: 0px;"><H4>Last update: 18/05/2010</H4></div>
82     </div>
83     </div>
84     <div id="linkline">
85    
86    
87     <!-- <a href="features.html">Features</a>-->
88 sng 52 <a class="here" href="../README.html">Offline Documentation</a>
89 sng 49
90    
91    
92    
93    
94     <!-- docline-top-->
95     <div id="docline-top"> <a href="partitions.html">&lt; PREV</a> <a href="../README.html">UP</a> <a href="own-scripts.html">NEXT &gt;</a> </div>
96     </div>
97     <div id="contarea">
98     <div id="content">
99     <a name="recover-top"></a>
100    
101     <!-- On the CD -->
102    
103     <H2 style="margin-top: 0;"><a name="recover-intro"></a>Intro <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H2>
104    
105     <p>Deleted or "lost" files can be recovered from failed or formatted drives and partitions, cdroms and memory cards using the software available in <b>SystemRescueCD</b>.
106    
107     Unless you can rule out hardware failure, you must not write to the failed device. The following software will passively try to recover your data from failed or failing hardware. If your data is not replaceable, do not attempt to write to the failed device if the following applications do not work but seek professional advice instead.<br>
108     <br>
109     If your device is damaged, it is advisable to image the device and work on the image file for data recovery. If hardware failure is not the problem, you can recover data directly from the device.<br>
110     <br>
111     To recover data from a failed device, you will need another device of equal or greater storage capacity onto which to save your data. If you need to make an image of the failed device, you will need yet another quantity of space.<br>
112     <br>
113     I should state here, that I haven't used any of these tools recently (other than plain and simple <b>dd</b>, a long time ago, which I found to be very slow), so I couldn't recommend any of them. Any comments on a tool's usability found in this page, is just what I found on the Net.</p>
114    
115    
116     <!-- Partition recovery -->
117     <H2><a name="recover-dr"></a>Partition recovery <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H2>
118    
119     <p>If you made a mistake while partitioning and the partition no longer appears in the partition table, so long as you have not written data in that space, all your data is still there and can be restored.</p>
120    
121     <p>When changing the partition table on your hard drive, you must ensure that no partition on the disk is mounted. This includes swap space. In order to restore your partition, execute:</p>
122    
123     <p class="newcode">swapoff -a<br>
124     parted /dev/old_disk</p>
125    
126     <p>Then, use the rescue option:</p>
127    
128     <p class="newcode">rescue START END</p>
129    
130     <p>where <b>START</b> is the area of the disk where you believe the partition began and <b>END</b> is it's end. If parted finds a potential partition, it will ask you if you want to add it to the partition table.</p>
131    
132     <p><b>Note:</b> <a href="#recover-testdisk">TestDisk</a> can also be used to recover a "lost" partition.</p>
133    
134     <!-- Disk recovery -->
135     <H2><a name="recover-dr"></a>Disk / files recovery <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H2>
136    
137     <!-- dd -->
138     <H3><a name="recover-dd"></a>Using dd <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H3>
139    
140     <p>In order to duplicate a disk to another disk, execute</p>
141    
142     <p class="newcode">dd if=/dev/old_disk of=/dev/new_disk conv=noerror,sync</p>
143    
144     <p>or to create an image file</p>
145    
146     <p class="newcode">dd if=/dev/old_disk of=image_file conv=noerror</p>
147    
148     <p>Be careful, if you are copying a disk, the destination must also be a disk, not a partition. If you are copying a partition, the destination partition must be large enough. Copying the whole disk is recommended.<br>
149     <br>
150     To speed up the copy process, you can append <b>bs=8k</b>, it will read/write the disk by 16 sectors at a time.</p>
151    
152    
153     <!-- dd_rescue -->
154     <H3><a name="recover-dd-rescue"></a>Using dd_rescue <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H3>
155    
156     <p>Like dd, <a href="http://www.garloff.de/kurt/linux/ddrescue/" target="_blank">dd_rescue</a> does copy data from one file or block device to another. You can specify file positions (called seek and skip in dd). There are several differences:</p>
157    
158     <ul>
159     <li>dd_rescue does not provide character conversions.</li>
160     <li>The command syntax is different. Call <b>dd_rescue -h</b>.</li>
161     <li>dd_rescue does not abort on errors on the input file, unless you specify a maximum error number. Then dd_rescue will abort when this number is reached.</li>
162     <li>dd_rescue does not truncate the output file, unless asked to.</li>
163     <li>You can tell dd_rescue to start from the end of a file and move backwards.</li>
164     <li>It uses two block sizes, a large (soft) block size and a small (hard) block size. In case of errors, the size falls back to the small one and is promoted again after a while without errors.</li>
165     <li>It does not (yet) support non-seekable in- or output.</li>
166     </ul>
167    
168     <p>In order to duplicate a disk to another disk, execute</p>
169    
170     <p class="newcode">dd_rescue -A -v /dev/old_disk /dev/new_disk</b></p>
171    
172     <p>or to create an image file</p>
173    
174     <p class="newcode">dd_rescue -A -v /dev/old_disk image_file</b></p>
175    
176     <p>The copying should go very quickly until it hits a bad sector and then it will slow down to take smaller chunks of data. People have reported very good results with this technique.</p>
177    
178    
179     <!-- GNU ddrescue -->
180     <H3><a name="recover-gnu-ddrescue"></a>Using GNU ddrescue <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H3>
181    
182     <p>The GNU site describes GNU ddrescue as a data recovery tool, and lists these features:</p>
183    
184     <ul>
185     <li>It copies data from one file or block device (hard disc, CD-ROM, etc) to another, trying hard to rescue data in case of read errors.</li>
186     <li>It does not truncate the output file if not asked to, so every time you run it on the same output file, it tries to fill in the gaps.</li>
187     <li>It is designed to be fully automatic.</li>
188     <li>If you use the log file feature of GNU ddrescue, the data is rescued very efficiently (only the needed blocks are read). Also you can interrupt the rescue at any time and resume it later at the same point.</li>
189     <li>The log file is periodically saved to disc. So in case of a crash you can resume the rescue with little recopying.</li>
190     <li>If you have two or more damaged copies of a file, CD-ROM, etc, and run GNU ddrescue on all of them, one at a time, with the same output file, you will probably obtain a complete and error-free file. The probability of having damaged areas at the same places on different input files is very low. Using the log file, only the needed blocks are read from the second and successive copies.</li>
191     <li>The same log file can be used for multiple commands that copy different areas of the file, and for multiple recovery attempts over different subsets.</li>
192     </ul>
193    
194     <p>The algorithm of GNU ddrescue is as follows:</p>
195    
196     <ol>
197     <li>Optionally read a log file describing the status of a multi-part or previously interrupted rescue.</li>
198     <li>Read the non-damaged parts of the input file, skipping the damaged areas, until the requested size is reached, or until interrupted by the user.</li>
199     <li>Try to read the damaged areas, splitting them into smaller pieces and reading the non-damaged pieces, until the hardware block size is reached, or until interrupted by the user.</li>
200     <li>Try to read the damaged hardware blocks until the specified number of retries is reached, or until interrupted by the user.</li>
201     <li>Optionally write a log file for later use.</li>
202     </ol>
203    
204     <p><b>Note:</b> GNU ddrescue is considered to be the best recovery tool available.</p>
205    
206     <p>In order to duplicate a disk to another disk, execute</p>
207    
208     <p class="newcode">ddrescue -vr3 /dev/old_disk /dev/new_disk logfile</b></p>
209    
210     <p>or to create an image file</p>
211    
212     <p class="newcode">ddrescue -vr3 /dev/old_disk image_file logfile</b></p>
213    
214     <p>If the disk is failing fast and you want to get the most data out of it on the first try, you should probably use "<b>-n</b>" on the first run. This will avoid splitting error areas. Subsequent runs can use "<b>-r1</b>" or "<b>-r3</b>", without "<b>-n</b>", to retry those error areas.</p>
215    
216     <p>To summarise, we execute:</p>
217    
218     <p class="newcode">ddrescue -vn /dev/old_disk image_file logfile<br>
219     ddrescue -v -r3 -C /dev/old_disk image_file logfile</p>
220    
221     <p><b>Note:</b> When working with CD-ROMs you should probably specific "<b>-b 2048</b>"</p>
222    
223    
224     <!-- Foremost -->
225     <H3><a name="recover-foremost"></a>Using Foremost <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H3>
226    
227     <p><a href="http://foremost.sourceforge.net/" target="_blank">Foremost</a> is a console program to recover files based on their headers, footers, and internal data structures. This process is commonly referred to as data carving. Foremost can work on image files, such as those generated by dd, Safeback, Encase, etc, or directly on a drive. The headers and footers can be specified by a configuration file or you can use command line switches to specify built-in file types. These built-in types look at the data structures of a given file format allowing for a more reliable and faster recovery.</p>
228    
229     <p>It can be run on an image file created with any of the above tools, to extract files:</p>
230    
231     <p class="newcode">foremost -i image -o /recovery/foremost</p>
232    
233     <p>Foremost can be instructed to recover only specific file types, using the <b>-t</b> command line parameter. In the following example Foremost will extract only jpg files:</p>
234    
235     <p class="newcode">foremost -t jpg -i image -o /recovery/foremost</p>
236    
237     <p>Available types are: jpg, gif, png, bmp, avi, exe (Windows binaries and DLLs), wav, riff, wmv (will extract wma also), mov, pdf, ole (will extract any file using the OLE file structure; this includes PowerPoint, Word, Excel, Access, and StarWriter), doc, zip (will extract .jar files and Open Office docs as well; this includes SXW, SXC, SXI, and SX? for undetermined OpenOffice files), rar, html and cpp.</p>
238    
239     <!-- TestDisk -->
240     <H3><a name="recover-testdisk"></a>Using TestDisk <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H3>
241    
242     <p><a href="http://www.cgsecurity.org/wiki/TestDisk" target="_blank">TestDisk</a> was primarily designed to help <b>recover "lost" partitions</b> and/or <b>make non-booting disks bootable again</b> <i>when</i> these symptoms are caused by <i>faulty software</i>, certain types of <i>viruses</i> or <i>human error</i> (such as <i>accidentally</i> deleting a Partition Table). Partition table recovery using TestDisk is really easy.<br>
243     <br>
244     TestDisk can</p>
245    
246     <ul>
247     <li> Fix partition table, recover deleted partition</li>
248     <li> Recover FAT32 boot sector from its backup</li>
249     <li> Rebuild FAT12/FAT16/FAT32 boot sector</li>
250     <li> Fix FAT tables</li>
251     <li> Rebuild NTFS boot sector</li>
252     <li> Recover NTFS boot sector from its backup</li>
253     <li> Fix MFT using MFT mirror</li>
254     <li> Locate ext2/ext3 Backup SuperBlock</li>
255     </ul>
256    
257     <p>Some great tutorials are available at TestDisk's site: "<a href="http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step" target="_blank">TestDisk Step By Step</a>", "<a href="http://www.cgsecurity.org/wiki/Running_TestDisk" target="_blank">Running TestDisk</a>", "<a href="http://www.cgsecurity.org/wiki/Data_Recovery_Examples" target="_blank">Data Recovery Examples</a>" etc.
258     </p>
259    
260     <!-- PhotoRec -->
261     <H3><a name="recover-photorec"></a>Using PhotoRec <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H3>
262    
263     <p><a href="http://www.cgsecurity.org/wiki/PhotoRec" target ="_blank">PhotoRec</a> is file data recovery software designed to recover "lost" files including video, documents and archives from Hard Disks and CDRom and "lost" pictures (thus, its 'Photo Recovery' name) from digital camera memory. PhotoRec ignores the filesystem and goes after the underlying data, so it will still work even if your media's filesystem has been severely damaged or re-formatted.<br>
264     <br>
265     For more safety, PhotoRec uses read-only access to handle the drive or memory support you are about to recover "lost" data from.<br>
266     <br>
267     <b>Important</b>: As soon as a pic or file is accidentally deleted, or you discover any missing, do NOT save any more pics or files to that memory device or hard disk drive; otherwise you may overwrite your "lost" data. This means that even using PhotoRec, you must not choose to write the recovered files to the same partition they were stored on.<br>
268     <br>
269     A great tutorial titled "<a href="http://www.cgsecurity.org/wiki/PhotoRec_Step_By_Step" target="_blank">PhotoRec Step By Step</a>" can be found at PhotoRec's site.</p>
270    
271    
272    
273     <!-- Links -->
274     <H2><a name="recover-links"></a>Links &amp; resources <span class="hideprint">[<a href="#help-top" title="go to top of the page">^</a>]</span></H2>
275    
276     <p>This page is a compilation of the following pages:</p>
277    
278     <p>DataRecovery<br>
279     &nbsp;&nbsp;&nbsp;&nbsp;<a href="https://help.ubuntu.com/community/DataRecovery" target="_blank">https://help.ubuntu.com/community/DataRecovery</a></p>
280    
281     <p>Hard Drive Recovery, Ubuntu-Style<br>
282     &nbsp;&nbsp;&nbsp;&nbsp;<a href="http://blogs.sun.com/superpat/tags/ddrescue" target="_blank">http://blogs.sun.com/superpat/tags/ddrescue</a></p>
283    
284     <p>Recover Data and (deleted) Partition with Linux from Hard Drives, CD-ROMs or DVDs<br>
285     &nbsp;&nbsp;&nbsp;&nbsp;<a href="http://sysblogd.wordpress.com/2008/01/05/data-recovery-with-linux-from-hard-drives-cd-roms-or-dvds/" target="_blank">http://sysblogd.wordpress.com/2008/01/05/data-recovery-with-linux-from-hard-drives-cd-roms-or-dvds/</a></p>
286    
287     <p>dd_rescue<br>
288     &nbsp;&nbsp;&nbsp;&nbsp;<a href="http://www.garloff.de/kurt/linux/ddrescue/" target="_blank">http://www.garloff.de/kurt/linux/ddrescue/</a></p>
289    
290     <p>gddrescue: a tool for recovering data from damaged media<br>
291     &nbsp;&nbsp;&nbsp;&nbsp;<a href="http://debaday.debian.net/2007/12/12/gddrescue-a-tool-for-recovering-data-from-damaged-media/" target="_blank">http://debaday.debian.net/2007/12/12/gddrescue-a-tool-for-recovering-data-from-damaged-media/</a></p>
292    
293     <p>Foremost<br>
294     &nbsp;&nbsp;&nbsp;&nbsp;<a href="http://foremost.sourceforge.net/" target="_blank">http://foremost.sourceforge.net/</a></p>
295    
296     <p>TestDisk<br>
297     &nbsp;&nbsp;&nbsp;&nbsp;<a href="http://www.cgsecurity.org/wiki/TestDisk" target="_blank">http://www.cgsecurity.org/wiki/TestDisk</a></p>
298    
299     <p>PhotoRec<br>
300     &nbsp;&nbsp;&nbsp;&nbsp;<a href="http://www.cgsecurity.org/wiki/PhotoRec" target="_blank">http://www.cgsecurity.org/wiki/PhotoRec</a></p>
301    
302    
303     </div>
304    
305    
306    
307     <!--<a name="template-top"></a>-->
308    
309     <div id="footer">
310     <div id="docline-bottom"> <a href="partitions.html">&lt; PREV</a> <a href="../README.html">UP</a> <a href="own-scripts.html">NEXT &gt;</a> </div>
311     <p>Copyright: &#169; <a href="mailto:&#115;&#110;&#103;&#064;&#104;&#101;&#108;&#108;&#117;&#103;&#046;&#103;&#114;?subject=About Clonezilla-SysRescCD v 3.1.0">Spiros Georgaras</a>, 2007-2010<br /><br/>
312     Hosted by <a href="http://www.hellug.gr" target="_blank" title="Hellenic Linux User Group">HEL.L.U.G.</a></p>
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