Timeline for Ext4 superblock overwritten
Current License: CC BY-SA 3.0
9 events
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| Dec 7, 2016 at 14:30 | comment | added | user3447279 | Sounds feasible that it has something to do with wear leveling, but I have no clue how I ever can reproduce such. We only had problems with the same SD-Card type till now. I will post it to this lists, thanks for the hint! | |
| Dec 7, 2016 at 13:37 | comment | added | kostix |
Would you consider posting a message to the debian-users mailing list -- also maybe Cc'ing tytso at mit.edu who maintains extfs tools in Debian and is the maintaier of extN in Linux? Maybe filing a bug request would do as well?
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| Dec 7, 2016 at 13:34 | comment | added | kostix | Are all your cards of the same make/model? | |
| Dec 7, 2016 at 13:33 | comment | added | kostix | re (2): I doubt so: "filesystem full" is a "soft" event which has nothing to do with the underlying medium which simply has no idea what the data stored on it even means. But WL, to my knowledge, is free to dynamically "remap" data: that is, it can grab data off one of its internal blocks, physically write it on another and move that original one into a "free list". The idea is to prevent constant re-writing of only a small amount of physical blocks for a typical case of a filesystem which usually keeps quite a bit of "static" data which hardly ever changes. | |
| Dec 7, 2016 at 10:10 | comment | added | user3447279 | 1.) we had this behaviour repeateadly and with multiple cards. Also I checked for badblocks which didnt show errors. 2.) I don´t know whether none/static/dynamic WL is used by SD-card controller (I am investigating) What would happen if the file system was full? Could that lead to bad mapping from wear leveling or so? | |
| Dec 6, 2016 at 15:25 | comment | added | kostix |
Say, your card could do wear leveling while having a bad internal block, and you were unfortunate to get that block mapped under the filesystem's superblock. Just an idea. If that's the case I'd advise to back up the whole card, swap it for another and run some diagnostics on the original (say, with badblocks in destructive mode).
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| Dec 6, 2016 at 15:22 | comment | added | kostix |
It's easily possible sinse "everything is a file"; for instance: dd if=/dev/random of=/dev/sda1 bs=1024 count=1 will overwrite the superblock on /dev/sda1 with random data. As to the second -- I have no idea. Obviously, such things don't happen under "normal" system activity. Isn't it possible that your SDHC card simply gone kaputt?
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| Dec 6, 2016 at 15:01 | review | First posts | |||
| Dec 7, 2016 at 10:31 | |||||
| Dec 6, 2016 at 14:54 | history | asked | user3447279 | CC BY-SA 3.0 |