56 lines
1.7 KiB
Markdown
56 lines
1.7 KiB
Markdown
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title = "disks backup"
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date = 2020-09-16
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tags = ["admin"]
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Backing up a whole disk is always quite sensible ; you rarely have the occasion
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to test if your backup really works. Besides, the logical architecture of a disk
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and its partitions can be quite sophisticated, with numerous different options,
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that vary much between operating systems. Here we will describe how to backup
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and restore a disk with some primary partitions. We will assume it is a bootable
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disk with a Master Boot Record at the very beginning of it (MBR is limited to
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446 bytes by conception). Note that most recent machines boot in UEFI mode,
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which is not covered here.
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## Backup a bootable disk
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Let's say your disk is called sdX.
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### Backup Master Boot Record
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The MBR is a portion of bootable binary code. Do not try to read it with any
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text editor ! They may slightly modify it, rendering it unbootable.
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$ dd if=/dev/sdX of=path/to/disk_backup.mbr bs=446 count=1
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### Backup partition table
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$ sfdisk -d /dev/sdX > path/to/disk_backup.partition_table.txt
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### Backup useful partitions
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For each partition (numbered Y) :
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$ dd if=/dev/sdXY of=path/to/partition_backup.dd status=progress
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Compressed variant :
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$ dd if=/dev/sdXY status=progress | gzip > path/to/partition_backup.dd.gz
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## Restore a backed up disk into sdX
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Edit `path/to/disk_backup.partition_table.txt` to reflect the partitions you
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will actually restore. Then :
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$ dd if=path/to/disk_backup.mbr of=/dev/sdX
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$ sfdisk /dev/sdX < path/to/disk_backup.partition_table.txt
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You might have to eject and re-plug the disk to see the added
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partitions. Then for each of those :
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$ zcat if=arch_zero_pY.dd.gz | dd of=/dev/sdXY
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And finally restore MBR :
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$ dd if=path/to/disk_backup.mbr of=/dev/sdX bs=446 count=1
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