Hello,
I've recently converted my root 32GB ext4 partition to btrfs (using
btrfs-progs 5.2). After that was done, I made a snapshot and tried to
update the system. Unfortunately I didn't have enough free space to
fit the whole update on that small partition, so it failed. I then
realized my mistake and deleted not only that newly made snapshot, but
also ext2_saved and some random files on the filesystem, totaling
about 5GB. For my surprise, the update still failed due to ENOSPC.
At this point, I tried running a balance, but it also failed with
ENOSPC. I tried the balance -dusage X with X increasing from zero, but
to my surprise again, it also failed.
Data, single: total=28.54GiB, used=28.34GiB
System, single: total=32.00MiB, used=16.00KiB
Metadata, single: total=1.00GiB, used=807.45MiB
GlobalReserve, single: total=41.44MiB, used=0.00B
Looking at btrfs filesystem df, it looks like those 5GB of data I
deleted are still occupying space. In fact, ncdu claims all the files
on that drive sum up to only 19GB.
I tried adding a second 2GB drive but that still wasn't enough to run
a full data balance (metadata runs fine).
This is what filesystem usage looks like:
Overall:
Device size: 31.59GiB
Device allocated: 29.57GiB
Device unallocated: 2.03GiB
Device missing: 0.00B
Used: 29.13GiB
Free (estimated): 2.22GiB (min: 2.22GiB)
Data ratio: 1.00
Metadata ratio: 1.00
Global reserve: 41.44MiB (used: 0.00B)
Data,single: Size:28.54GiB, Used:28.34GiB
/dev/sda7 768.00MiB
/dev/sdb1 27.79GiB
Metadata,single: Size:1.00GiB, Used:807.45MiB
/dev/sdb1 1.00GiB
System,single: Size:32.00MiB, Used:16.00KiB
/dev/sdb1 32.00MiB
Unallocated:
/dev/sda7 1.03GiB
/dev/sdb1 1.00GiB
I then made a read-only snapshot of the root filesystem and used btrfs
send/receive to transfer it to another btrfs filesystem, and when it
got there its also only occupying 19GB.
So there seems 10GB got lost somewhere in the process and I can't find
a way to get them back (other thank mkfs'ing and restoring a backup),
which in this case is about 30% of the available disk space.
What may be causing this?
Thanks,
Daniel.
