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| author | Adam T. Carpenter <atc@53hor.net> | 2021-04-21 22:57:39 -0400 |
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| committer | Adam T. Carpenter <atc@53hor.net> | 2021-04-21 22:57:39 -0400 |
| commit | 890b34bcc1a6b4073d1e512b1386634f7bc5ea52 (patch) | |
| tree | 17efbec82a5bc118c2ae0b3ec56acbf159e4edda /posts/unix/2019-09-28-my-preferred-method-for-data-recovery.html | |
| parent | e87bdb082057c4eddd1af159374b667c7fe234d4 (diff) | |
| download | 53hor-890b34bcc1a6b4073d1e512b1386634f7bc5ea52.tar.xz 53hor-890b34bcc1a6b4073d1e512b1386634f7bc5ea52.zip | |
unified posts dir, until I can figure out makefile sub-subdirs. makefile auto-generates index
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| -rw-r--r-- | posts/unix/2019-09-28-my-preferred-method-for-data-recovery.html | 276 |
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diff --git a/posts/unix/2019-09-28-my-preferred-method-for-data-recovery.html b/posts/unix/2019-09-28-my-preferred-method-for-data-recovery.html deleted file mode 100644 index 9751eda..0000000 --- a/posts/unix/2019-09-28-my-preferred-method-for-data-recovery.html +++ /dev/null @@ -1,276 +0,0 @@ -<!DOCTYPE html> -<html> - <head> - <link rel="stylesheet" href="/includes/stylesheet.css" /> - <meta charset="utf-8" /> - <meta name="viewport" content="width=device-width, initial-scale=1" /> - <meta - property="og:description" - content="The World Wide Web pages of Adam Carpenter" - /> - <meta property="og:image" content="https://nextcloud.53hor.net/index.php/s/Nx9e7iHbw4t99wo/preview" /> - <meta property="og:site_name" content="53hor.net" /> - <meta property="og:title" content="How I Do Data Recovery" /> - <meta property="og:type" content="website" /> - <meta property="og:url" content="https://www.53hor.net" /> - <title>53hornet ➙ How I Do Data Recovery</title> - </head> - - <body> - <nav> - <ul> - <li> - <a href="/"> - <img src="/includes/icons/home-roof.svg" /> - Home - </a> - </li> - <li> - <a href="/info.html"> - <img src="/includes/icons/information-variant.svg" /> - Info - </a> - </li> - <li> - <a href="https://git.53hor.net"> - <img src="/includes/icons/git.svg" /> - Repos - </a> - </li> - <li> - <a href="/hosted.html"> - <img src="/includes/icons/desktop-tower.svg" /> - Hosted - </a> - </li> - <li> - <a type="application/rss+xml" href="/rss.xml"> - <img src="/includes/icons/rss.svg" /> - RSS - </a> - </li> - </ul> - </nav> - - <article> - <h1>How I Do Data Recovery</h1> - - <p> - This week Amy plugged in her flash drive to discover that there were no - files on it. Weeks before there had been dozens of large cuts of footage - that she needed to edit down for work. Hours of recordings were - seemingly gone. And the most annoying part was the drive had worked - perfectly on several other occasions. Just not now that the footage was - actually needed of course. Initially it looked like everything had been - wiped clean, however both Amy's Mac and her PC thought the drive was - half full. It's overall capacity was 64GB but it showed only about 36GB - free. So there still had to be data on there if we could find the right - tool to salvage it. - </p> - - <p> - Luckily this wasn't the first time I had to recover accidentally (or - magically) deleted files. I had previously done so with some success at - my tech support job, for some college friends, and for my in-laws' - retired laptops. So I had a pretty clear idea of what to expect. The - only trick was finding a tool that knew what files it was looking for. - The camera that took the video clips was a Sony and apparently they - record into <code>m2ts</code> files, which are kind of a unique format - in that they only show up on Blu-Ray discs and Sony camcorders. Enter my - favorite two tools for dealing with potentially-destroyed data: - <code>ddrescue</code> and <code>photorec</code>. - </p> - - <h2>DDRescue</h2> - - <p> - <code>ddrescue</code> is a godsend of a tool. If you've ever used - <code>dd</code> before, forget about it. Use <code>ddrescue</code>. You - might as well <code>alias dd=ddrescue</code> because it's that great. By - default it has a plethora of additional options, displays the progress - as it works, recovers and retries in the event of I/O errors, and does - everything that good old <code>dd</code> can do. It's particularly good - at protecting partitions or disks that have been corrupted or damaged by - rescuing undamaged portions first. Oh, and have you ever had to cancel a - <code>dd</code> operation? Did I mention that <code>ddrescue</code> can - pause and resume operations? It's that good. - </p> - - <h2>PhotoRec</h2> - - <p> - <code>photorec</code> is probably the best missing file recovery tool - I've ever used in my entire life. And I've used quite a few. I've never - had as good results as I've had with <code>photorec</code> with other - tools like Recuva et. al. And <code>photorec</code> isn't just for - photos, it can recover documents (a la Office suite), music, images, - config files, and videos (including the very odd - <code>m2ts</code> format!). The other nice thing is - <code>photorec</code> will work on just about any source. It's also free - software which makes me wonder why there are like $50 recovery tools for - Windows that look super sketchy. - </p> - - <h2>In Practice</h2> - - <p> - So here's what I did to get Amy's files back. Luckily she didn't write - anything out to the drive afterward so the chances (I thought) were - pretty good that I would get <em>something</em> back. The first thing I - always do is make a full image of whatever media I'm trying to recover - from. I do this for a couple of reasons. First of all it's a backup. If - something goes wrong during recovery I don't have to worry about the - original, fragile media being damaged or wiped. Furthermore, I can work - with multiple copies at a time. If it's a large image that means - multiple tools or even multiple PCs can work on it at once. It's also - just plain faster working off a disk image than a measly flash drive. So - I used <code>ddrescue</code> to make an image of Amy's drive. - </p> - - <pre><code> -$ sudo ddrescue /dev/sdb1 amy-lexar.dd -GNU ddrescue 1.24 -Press Ctrl-C to interrupt - ipos: 54198 kB, non-trimmed: 0 B, current rate: 7864 kB/s - opos: 54198 kB, non-scraped: 0 B, average rate: 18066 kB/s -non-tried: 63967 MB, bad-sector: 0 B, error rate: 0 B/s - rescued: 54198 kB, bad areas: 0, run time: 2s -pct rescued: 0.08%, read errors: 0, remaining time: 59m - time since last successful read: n/a -Copying non-tried blocks... Pass 1 (forwards) - </code></pre> - - <p> - The result was a very large partition image that I could fearlessly play - around with. - </p> - - <pre> - <code> -$ ll amy-lexar.dd --rw-r--r-- 1 root root 60G Sep 24 02:45 amy-lexar.dd - </code> - </pre> - - <p> - Then I could run <code>photorec</code> on the image. This brings up a - TUI with all of the listed media that I can try and recover from. - </p> - - <pre><code> -$ sudo photorec amy-lexar.dd - -PhotoRec 7.0, Data Recovery Utility, April 2015 -http://www.cgsecurity.org - - PhotoRec is free software, and -comes with ABSOLUTELY NO WARRANTY. - -Select a media (use Arrow keys, then press Enter): ->Disk amy-lexar.dd - 64 GB / 59 GiB (RO) - ->[Proceed ] [ Quit ] - -Note: -Disk capacity must be correctly detected for a successful recovery. -If a disk listed above has incorrect size, check HD jumper settings, BIOS -detection, and install the latest OS patches and disk drivers. - </code></pre> - - <p> - After hitting proceed <code>photorec</code> asks if you want to scan - just a particular partition or the whole disk (if you made a whole disk - image). I can usually get away with just selecting the partition I know - the files are on and starting a search. - </p> - - <pre><code> -PhotoRec 7.0, Data Recovery Utility, April 2015 -http://www.cgsecurity.org - -Disk amy-lexar.dd - 64 GB / 59 GiB (RO) - - Partition Start End Size in sectors - Unknown 0 0 1 7783 139 4 125042656 [Whole disk] -> P FAT32 0 0 1 7783 139 4 125042656 [NO NAME] - ->[ Search ] [Options ] [File Opt] [ Quit ] - Start file recovery - </code></pre> - - <p> - Then <code>photorec</code> asks a couple of questions about the - formatting of the media. It can usually figure them out all by itself so - I just use the default options unless it's way out in left field. - </p> - - <pre><code> -PhotoRec 7.0, Data Recovery Utility, April 2015 -http://www.cgsecurity.org - - P FAT32 0 0 1 7783 139 4 125042656 [NO NAME] - -To recover lost files, PhotoRec need to know the filesystem type where the -file were stored: - [ ext2/ext3 ] ext2/ext3/ext4 filesystem ->[ Other ] FAT/NTFS/HFS+/ReiserFS/... - </code></pre> - - <p> - Now this menu is where I don't just go with the default path. - <code>photorec</code> will offer to search just unallocated space or the - entire partition. I always go for the whole partition here; sometimes - I'll get back files that I didn't really care about but more often than - not I end up rescuing more data this way. In this scenario searching - just unallocated space found no files at all. So I told - <code>photorec</code> to search everything. - </p> - - <pre><code> -PhotoRec 7.0, Data Recovery Utility, April 2015 -http://www.cgsecurity.org - - P FAT32 0 0 1 7783 139 4 125042656 [NO NAME] - - -Please choose if all space need to be analysed: - [ Free ] Scan for file from FAT32 unallocated space only ->[ Whole ] Extract files from whole partition - </code></pre> - - <p> - Now it'll ask where you want to save any files it finds. I threw them - all into a directory under home that I could zip up and send to Amy's - Mac later. - </p> - - <pre><code> -PhotoRec 7.0, Data Recovery Utility, April 2015 - -Please select a destination to save the recovered files. -Do not choose to write the files to the same partition they were stored on. -Keys: Arrow keys to select another directory - C when the destination is correct - Q to quit -Directory /home/adam - drwx------ 1000 1000 4096 28-Sep-2019 12:10 . - drwxr-xr-x 0 0 4096 26-Jan-2019 15:32 .. ->drwxr-xr-x 1000 1000 4096 28-Sep-2019 12:10 amy-lexar-recovery - </code></pre> - - <p> - And then just press <code>C</code>. <code>photrec</code> will start - copying all of the files it finds into that directory. It reports what - kinds of files it found and how many it was able to locate. I was able - to recover all of Amy's lost footage this way, past, along with some - straggler files that had been on the drive at one point. This has worked - for me many times in the past, both on newer devices like flash drives - and on super old, sketchy IDE hard drives. I probably won't ever pay for - data recovery unless a drive has been physically damaged in some way. In - other words, this software works great for me and I don't foresee the - need for anything else out there. It's simple to use and is typically - pretty reliable. - </p> - </article> - </body> -</html> |