52 lines
1.8 KiB
Markdown
52 lines
1.8 KiB
Markdown
---
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title: Guide to recover data from damaged HDD
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date: 2018-02-15 12:45:00 +09:00
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---
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This is a complete guide describes how to rescue your data from old and wrecked HDD.
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Suppose you are using macOS and your endangered disk is formatted with HFS+.
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# Beforehand
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## Inspect
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Use `diskutil list` to verify that which drive is damaged.
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This article assumes that `disk2` is the damaged AND a partition `disk2s2` is what you expected to be rescued. You don't want to save `disk2s1` that is usually EFI partition.
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## Damage Control
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To prevent extra load, unmount the damaged disk: `diskutil unmountDisk disk2`.
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# Rescue
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If you never been `ddrescue`, `brew install ddrescue` to install them on your machine.
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```bash
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cd /Volumes/AnotherDriveLargerThanDamagedDrive
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sudo ddrescue -n -v /dev/disk2s2 ./hdimage.dmg ./mapfile
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```
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So this command will start rescuing your data from `/dev/disk2s2` partition to `hdimage.dmg` while writing log to `mapfile`.
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You might want to rescue data as fast as possible. option `-n` is here for. This will skip scraping phase that causes aggressive disk access.
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Option `-v` stand for verbose logging.
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```bash
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sudo ddrescue -r5 -v /dev/rdisk2s2 ./hdimage.dmg ./mapfile
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```
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When the first command completed, do it again with different parameters to aggressively scrape bad area failed to access the first time.
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Option `-r5` means ddrescue will try rescuing damaged area for 5 times.
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And `/dev/disk2s2` become `/dev/rdisk2s2` this time. `r` stand for raw so this will access the disk more direct way.
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> Beware: You MUST use same `hdimage.dmg` and `mapfile` between two commands. `mapfile` remains information of which blocks were rescued.
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# Aftercare
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Mount `hdimage.dmg` and copy files and directories to a new drive. If the image is broken, you can recover it using `testdisk`.
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