On Tue, Jan 28, 2020 at 6:55 PM CASS Philip <p.cass(a)epcc.ed.ac.uk> wrote:
Hi Greg,
Thanks – if I understand
https://ceph.io/geen-categorie/get-omap-keyvalue-size/ correctly, “rados
-p cephfs.fs1-replicated.data ls” should show any such objects? It’s also
returning blank (and correctly returns a lot for the EC pool).
That being said – if it’s only written to by the MDS in any case, my
concerns are moot. Do clients need _*read*_ access to the default pool
either?
Regards,
Phil
_________________________________________
*Philip Cass*
*HPC Systems Specialist – Senior Systems Administrator *
*EPCC*
Advanced Computing Facility
Bush Estate
Penicuik
*Tel:* +44 (0)131 4457815
*Email:* p.cass(a)epcc.ed.ac.uk
_________________________________________
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*From:* Gregory Farnum <gfarnum(a)redhat.com>
*Sent:* 28 January 2020 17:13
*To:* CASS Philip <p.cass(a)epcc.ed.ac.uk>
*Cc:* ceph-users(a)ceph.io
*Subject:* Re: [ceph-users] CephFS - objects in default data pool
On Tue, Jan 28, 2020 at 4:26 PM CASS Philip <p.cass(a)epcc.ed.ac.uk> wrote:
I have a query about
https://docs.ceph.com/docs/master/cephfs/createfs/:
“The data pool used to create the file system is the “default” data pool
and the location for storing all inode backtrace information, used for hard
link management and disaster recovery. For this reason, all inodes created
in CephFS have at least one object in the default data pool.”
This does not match my experience (nautilus servers, nautlius FUSE client
or Centos 7 kernel client). I have a cephfs with a replicated top-level
pool and a directory set to use erasure coding with setfattr, though I also
did the same test using the subvolume commands with the same result. "Ceph
df detail" shows no objects used in the top level pool, as shown in
https://gist.github.com/pcass-epcc/af24081cf014a66809e801f33bcb535b (also
displayed in-line below)
Hmm I think this is tripping over the longstanding issue that omap data is
not reflected in the pool stats (although I would expect it to still show
up as objects, but perhaps the "ceph df" view has a different reporting
chain? Or else I'm confused somehow.)
But anyway...
It would be useful if indeed clients didn’t have to write to the top-level
pool, since that would mean we could give different clients permission only
to pool-associated subdirectories without giving everyone write access to a
pool with data structures shared between all users of the filesystem.
*Clients* don't need write permission to the default data pool unless you
want them to write files there. The backtraces are maintained by the MDS. :)
-Greg
[root@hdr-admon01 ec]# ceph df detail; ceph fs ls; ceph fs status
RAW STORAGE:
CLASS SIZE AVAIL USED RAW USED %RAW USED
hdd 3.3 PiB 3.3 PiB 32 TiB 32 TiB 0.95
nvme 2.9 TiB 2.9 TiB 504 MiB 2.5 GiB 0.08
TOTAL 3.3 PiB 3.3 PiB 32 TiB 32 TiB 0.95
POOLS:
POOL ID STORED OBJECTS
USED %USED MAX AVAIL QUOTA OBJECTS QUOTA BYTES
DIRTY USED COMPR UNDER COMPR
cephfs.fs1.metadata 5 162 MiB 63 324
MiB 0.01 1.4 TiB N/A N/A
63 0 B 0 B
cephfs.fs1-replicated.data 6 0 B 0 0
B 0 1.0 PiB N/A N/A
0 0 B 0 B
cephfs.fs1-ec.data 7 8.0 GiB 2.05k 11
GiB 0 2.4 PiB N/A N/A
2.05k 0 B 0 B
name: fs1, metadata pool: cephfs.fs1.metadata, data pools:
[cephfs.fs1-replicated.data cephfs.fs1-ec.data ]
fs1 - 4 clients
===
+------+--------+------------+---------------+-------+-------+
| Rank | State | MDS | Activity | dns | inos |
+------+--------+------------+---------------+-------+-------+
| 0 | active | hdr-meta02 | Reqs: 0 /s | 29 | 16 |
+------+--------+------------+---------------+-------+-------+
+----------------------------+----------+-------+-------+
| Pool | type | used | avail |
+----------------------------+----------+-------+-------+
| cephfs.fs1.metadata | metadata | 324M | 1414G |
| cephfs.fs1-replicated.data | data | 0 | 1063T |
| cephfs.fs1-ec.data | data | 11.4G | 2505T |
+----------------------------+----------+-------+-------+
+-------------+
| Standby MDS |
+-------------+
| hdr-meta01 |
+-------------+
MDS version: ceph version 14.2.5
(ad5bd132e1492173c85fda2cc863152730b16a92) nautilus (stable)
[root@hdr-admon01 ec]# ll /test-fs/ec/
total 12582912
-rw-r--r--. 1 root root 4294967296 Jan 27 22:26 new-file
-rw-r--r--. 2 root root 4294967296 Jan 28 14:06 new-file2
-rw-r--r--. 2 root root 4294967296 Jan 28 14:06
new-file-same-inode-as-newfile2
Regards,
Phil
_________________________________________
*Philip Cass*
*HPC Systems Specialist – Senior Systems Administrator *
*EPCC*
Advanced Computing Facility
Bush Estate
Penicuik
*Tel:* +44 (0)131 4457815
*Email:* p.cass(a)epcc.ed.ac.uk
_________________________________________
The University of Edinburgh is a charitable body, registered in Scotland,
with registration number SC005336.
The information contained in this e-mail (including any attachments) is
confidential and is intended for the use of the addressee only. If you
have received this message in error, please delete it and notify the
originator immediately.
Please consider the environment before printing this email.
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