SMR drive test 3: full 8TB partition, mount problems, fsck error after delete

[Marc Lehmann <schmorp@schmorp.de>]

Third test, using the full device, on linux 4.2.1

   mkfs.f2fs -l COLD1 -o1 -a0 -d1 -s128 /dev/mapper/xmnt-cold1
   mount -tf2fs -onoatime,flush_merge,active_logs=2,no_heap /dev/mapper/xmnt-cold1 /cold1

Unfortunately, mount failed with. The kernel showed that a high order
allocation could not be satisfied:

   mount: page allocation failure: order:7, mode:0x40d0
   ...
   F2FS-fs (dm-18): Failed to initialize F2FS segment manager
   (http://data.plan9.de/f2fs-mount-failure.txt)

I think this memory management is a real problem - the server was booted
about 20 minutes earlier and had 23GB free ram (used for cache). I was able
to mount it by dropping the page cache, but clearly this shouldn't be
neccessary.

After this, df showed 185GB in use, which is more like 3%, not 1% - again
overprovisioning seems to be out of bounds.

I started copying files with tar|tar, after 10GB, I restarted, which started
to overwrite the existing 10GB files.

Unfortunately, this time the GC kicked in every 10-20 seconds, slowing down
writing times. I don't know what triggered it this time, but I am quite sure
at less than 1% utilisation it shouldn't feel the need to gc while the disk
is busy writing.

After 90GB were written, I decided to simulate a disk problem by deleting
the device (to avoid any corruption issues the disk itself might have):

   echo 1 >/sys/block/sde/device/delete

After rescanning the device, I used fsck.f2fs on it, and it failed quickly:

   Info: superblock features = 0 : 
   Info: superblock encrypt level = 0, salt = 00000000000000000000000000000000
   Info: total FS sectors = 15628050432 (7630884 MB)
   Info: CKPT version = 2
   [ASSERT] (restore_node_summary: 688) ret >= 0
   [Exit 255] 

Re-running it with -f failed differently, but also quickly:

   Info: superblock features = 0 : 
   Info: superblock encrypt level = 0, salt = 00000000000000000000000000000000
   Info: total FS sectors = 15628050432 (7630884 MB)
   Info: CKPT version = 2
   [ASSERT] (get_current_sit_page: 803) ret >= 0
   [Exit 255] 

I'll reformat and try without any simulated problems.

-- 
                The choice of a       Deliantra, the free code+content MORPG
      -----==-     _GNU_              http://www.deliantra.net
      ----==-- _       generation
      ---==---(_)__  __ ____  __      Marc Lehmann
      --==---/ / _ \/ // /\ \/ /      schmorp@schmorp.de
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