Ceph » CephFS

The "ceph.dir.rbytes" xattr on .snap/<snap_name> directory is getting updated on already taken snapshots.
Check the details below.

On a vstart environment created with "env MDS=3 ../src/vstart.sh -d -b -n --without-dashboard"

1. Create subvolume

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# bin/ceph fs subvolume create a sub_0
*** DEVELOPER MODE: setting PATH, PYTHONPATH and LD_LIBRARY_PATH ***
2020-05-14T15:39:13.132+0530 7f88d9b27700 -1 WARNING: all dangerous and experimental features are enabled.
2020-05-14T15:39:13.156+0530 7f88d9b27700 -1 WARNING: all dangerous and experimental features are enabled.

2. List created subvolume

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# bin/ceph fs subvolume ls a
* DEVELOPER MODE: setting PATH, PYTHONPATH and LD_LIBRARY_PATH *
2020-05-14T15:39:28.432+0530 7f03423b1700 -1 WARNING: all dangerous and experimental features are enabled.
2020-05-14T15:39:28.452+0530 7f03423b1700 -1 WARNING: all dangerous and experimental features are enabled.
[
    {
        "name": "sub_0" 
    }
]

3. Write 1GB file to the subvolume

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# dd if=/dev/zero of=/mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/file1 bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.0127988 s, 81.9 MB/s

4. Create a snapshot

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# bin/ceph fs subvolume snapshot create a sub_0 snap_sub_0
*** DEVELOPER MODE: setting PATH, PYTHONPATH and LD_LIBRARY_PATH ***
2020-05-14T15:41:52.948+0530 7f6f40135700 -1 WARNING: all dangerous and experimental features are enabled.
2020-05-14T15:41:52.972+0530 7f6f40135700 -1 WARNING: all dangerous and experimental features are enabled.

5. List snapshot

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# bin/ceph fs subvolume snapshot ls a sub_0
*** DEVELOPER MODE: setting PATH, PYTHONPATH and LD_LIBRARY_PATH ***
2020-05-14T15:42:04.940+0530 7fe14cb06700 -1 WARNING: all dangerous and experimental features are enabled.
2020-05-14T15:42:04.964+0530 7fe14cb06700 -1 WARNING: all dangerous and experimental features are enabled.
[
    {
        "name": "snap_sub_0" 
    }
]

6. Get rbytes on subvolume directory

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# getfattr -d -m . -e text /mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/
getfattr: Removing leading '/' from absolute path names
file: mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/
ceph.dir.entries="1" 
ceph.dir.files="1" 
ceph.dir.rbytes="1048576"               
ceph.dir.rctime="1589455578.148494821" 
ceph.dir.rentries="2" 
ceph.dir.rfiles="1" 
ceph.dir.rsubdirs="1" 
ceph.dir.subdirs="0" 

7. Get rbytes on snap directory

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# getfattr -d -m . -e text /mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/.snap/snap_sub_0/
getfattr: Removing leading '/' from absolute path names
file: mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/.snap/snap_sub_0/
ceph.dir.entries="1" 
ceph.dir.files="1" 
ceph.dir.rbytes="1048576" 
ceph.dir.rctime="1589455578.148494821" 
ceph.dir.rentries="2" 
ceph.dir.rfiles="1" 
ceph.dir.rsubdirs="1" 
ceph.dir.subdirs="0" 
ceph.snap.btime="1589455578.148494821" 

8. Create another 1G file

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# dd if=/dev/zero of=/mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/file2 bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.00110732 s, 947 MB/s

9. Get rbytes on subvolume. It gets updated to reflect 2GB

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# getfattr -d -m . -e text /mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/
getfattr: Removing leading '/' from absolute path names
file: mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/
ceph.dir.entries="2" 
ceph.dir.files="2" 
ceph.dir.rbytes="2097152" 
ceph.dir.rctime="1589455807.534189066" 
ceph.dir.rentries="3" 
ceph.dir.rfiles="2" 
ceph.dir.rsubdirs="1" 
ceph.dir.subdirs="0" 

10. Get rbytes on snap directory. It also is updated with 2GB.

root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# 
root@kotresh-T490s:~/sandbox/kotresh-ceph/ceph/build# getfattr -d -m . -e text /mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/.snap/snap_sub_0/
getfattr: Removing leading '/' from absolute path names
# file: mnt/volumes/_nogroup/sub_0/af4abd14-41e6-4843-9945-96a0d0b48128/.snap/snap_sub_0/
ceph.dir.entries="1" 
ceph.dir.files="1" 
ceph.dir.rbytes="2097152" 
ceph.dir.rctime="1589455807.534189066" 
ceph.dir.rentries="3" 
ceph.dir.rfiles="2" 
ceph.dir.rsubdirs="1" 
ceph.dir.subdirs="0" 
ceph.snap.btime="1589455578.148494821"