[how-to] Btrfs allocation 100% - What can i do? - Get more space with outsorcing to SD-Card [HIGHRISK-READ-CAREFULLY-BEFORE-TRY]
asked 2016-05-04 11:23:00 +0200
!!! WARNING: READ CAREFULLY AND COMPLETLY BEFORE DOING SOMETHING - HIGHRISK OF BTRFS CORRUPTION AND NEED OF DEVICE BRIK IF DONE WRONG !!!
Btrfs is a cool file system, but with all cool things there are also uncool trace-appearance, too. One of this is that the Btrfs seems to run full of space. This means it have a poor performance like a fraqmented FAT device. So we have to maintain our filesystem fequently.
Note: It´s better that your device is connected to the carger and not in use while doing this. Also do not boot your device while it is not finished. The device may be unresponsible for a long time, because it need a lot of performance, be patient and wait.
Edit: To reduce the risk of breaking your device, go to Airplain-Mode, close all open apps and stop dalvik
!!! WARNING !!! NEVER, NEVER BOOT WHILE BALANCING - IT WILL BREAK YOUR DEVICE !!!
Doing by terminal
Enter Root mode
devel-su
Check the allocation (how many space is free / how unbalanced is your filesystem)
btrfs-balancer allocation
Note: everything over 90% is critical for the performance and the stability of the system
Balance the Btrfs Filesystem
btrfs-balancer balance
Now you can realocate the data chunks
btrfs balance start -dusage=55 /
If no space is left, try a lower number. But retry later with higher numbers up to 90% Edit: more than 90% can sometimes make your device to stay at a unresponsible condition for a long time > 12 h
Sometimes the Metadata also unbalanced, you can also realocate the metadata using this
btrfs balance start -musage=55 /
Note: The option -d stand for data and -m for metadata
Now we create a new loop device on the sd-card to outsorce space for balancing
First we have to check what name our sdcard have
ls /media/sdcard
Now we create a loop device on the sdcard and set it up to btrfs
dd if=/dev/zero of=/media/sdcard/***ID-OF-YOUR-SDCARD***/btrfs bs=100M count=5
losetup -v -f /media/sdcard/***ID-OF-YOUR-SDCARD***/btrfs
btrfs device add /dev/loop0 /
Now we can retry to balance the filesystem.
After balancing is finished, delete the Loop0 device. I´m not sure whats happens if you reboot / disconnect your sdcard while Loop0 is existing.
btrfs device delete /dev/loop0 /
Edit: It seems to be that in some cases the whole btrfs File system will be corrupted if /dev/loop0 will not be deleted before reboot.
If /dev/loop0 can not be deleted, never reboot! Try to balance again and again, delete local data until you can delete it. Write here for help but never reboot it. Hope this will help other solving the btrfs problem
Thanks to: https://together.jolla.com/question/30822/root-and-home-disks-full-and-causing-various-problems/ @juho, https://btrfs.wiki.kernel.org/index.php/Balance_Filters
Edit: Have anyone an other solution for the situation that the Loop0 can not be deleted?
Why creating this duplicate for the question you refer too? Everything you mention is already there, except the
Sthocs ( 2016-05-04 11:58:05 +0200 )edit-musageoption. You can simply suggest @Manatus to add it, instead of splitting the information.2 reduce, silplify and explain what we do at the terminal. Often i see howtos without description what the comand do. Yes, i´m it professional, but what will a unproffesional think.
I do this additional, that other can see the possibility tho outsorce the /dev/zero. Offcorse i found this coincidentally
There was no chance to find it at the search
evo3de ( 2016-05-04 12:35:49 +0200 )editI think this is very helpful since I'm a complete novice when talking about commandline. It is nice to have descriptions and everything in chronological order.
I have used commandline just once since the discussions about the code are usually just gibberish for a guy like me who uses jolla just because I want to support european operating system, not because I want code my own distro or use commandline to make a call.
The first time I used command line was last week because I ran in problems with warehouse and had to change the version to saimaa from "latest" it is sometimes a pain in the ass to find info from TJC if one does hardly know what to look for.
anza ( 2016-05-04 14:20:46 +0200 )editThat article of mine has spawled a bit out of my hands, eg. I don't know where to go from there. I thought of deleting it and doing simple instructions in the style of this how-to, but then it summarizes the problem pretty good currently, so it is more useful in that old form. (Which is also why I haven't wikied it.)
I think that how-to-article is a good way to go with this useful (bit risky) trick. Thanks!
Manatus ( 2016-05-04 14:32:26 +0200 )editLast command "btrfs device delete /dev/loop0 /" didn't worked for me and now my device have btrfs file system corrupted and, as far I tried, can not be repaired. I'll try a full recovery tomorrow. :(
tvicol ( 2016-05-04 19:39:46 +0200 )edit