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1d
comment Raid 5 not starting
output for third disk is missing? Basically it's a two disk failure, if you have logs, check what happened at sda1's Update Time:. Might be a case for --assemble --force but corruption is possible.
Nov
25
answered losetup /dev/loop0 disappears after some time
Nov
24
answered RAID-1 doesn't Assemble, elements listed as SPARE, how to recover?
Nov
24
comment Converting sparse file to non-sparse in place
@Ivan, also if it's a sparse filesystem image, you could just mount it and zero the free space inside of it, instead of using the complicated dd method above. It's the kind of detail you should have mentioned in the question... ;)
Nov
24
comment Converting sparse file to non-sparse in place
@Ivan, it may be better to just drop the sparse property when you untar then; less likely to produce a file with many fragments, which you usually get if you have a filesystem as a sparse file with holes all over the place. Then again, some virtualization solutions deliberately punch holes in files (TRIM support inside the VM) to save storage space on the host. Personally, I prefer giving real block devices to VMs instead of file containers.
Nov
24
comment Converting sparse file to non-sparse in place
@StéphaneChazelas, yup, but this -z does not keep your data if you happen to get an offset wrong, so I'll stick to dd there...
Nov
24
revised Converting sparse file to non-sparse in place
added 504 characters in body
Nov
24
comment Converting sparse file to non-sparse in place
@StéphaneChazelas, thanks, forgot about fallocate. It has --dig-holes but no --fill-holes. However, it seems to work well enough when you specify the size. I will edit my answer.
Nov
24
revised Converting sparse file to non-sparse in place
deleted 16 characters in body
Nov
24
revised Converting sparse file to non-sparse in place
added 241 characters in body
Nov
24
answered Converting sparse file to non-sparse in place
Nov
23
answered SSD not persistent
Nov
20
comment How can `dd` be used to right-shift data blocks?
What happens if ddrescue discovers a bad block in this scenario? If it jumps to another area of the disk (to avoid bad blocks), and continues copying from there, it would again overwrite not yet copied parts of your data. If it doesn't expect to work with the same device, it has no reason to take any special measures to prevent various possible data corruption cases.
Nov
20
comment How can `dd` be used to right-shift data blocks?
@starfry: sure, a program that just does it will be a nice solution. However I'm not at all sure about ddrescue here. Not if it expects to be working on different devices, and you have to trick it into accepting your arguments. It might not not have the "minimum buffer fill" property internally either (since with different devices it's not needed), so again it could corrupt your data. You'd have to check in the sourcecode whether it's actually designed for your use case.
Nov
16
awarded  Nice Answer
Nov
16
comment Raid 5 not starting
show full output
Nov
14
revised How can `dd` be used to right-shift data blocks?
added 30 characters in body
Nov
14
answered How can `dd` be used to right-shift data blocks?
Nov
11
comment mdadm RAID 5 and parted unrecognized disk label
And what's in dmesg after trying to mount with -t ext3? Also, check that your kernel supports GPT as well as ext3. Partitioning is not required, but recommended.
Nov
5
comment Software RAID10 setup writes small files extremely slowly, is this normal?
raid5/6 don't work with the full chunk either. the chunksize is more about physical distribution; the parity calculation takes smaller units