:~# rbd info RBD_HDD/2ef34a96-27e0-4ae7-9888-fd33c38f657a
rbd image '2ef34a96-27e0-4ae7-9888-fd33c38f657a':
size 51200 MB in 12800 objects
order 22 (4096 kB objects)
block_name_prefix: rbd_data.37c8974b0dc51
format: 2
features: layering, exclusive-lock, object-map, fast-diff, deep-flatten
flags:
create_timestamp: Sat May 5 11:39:07 2018
:~# rbd journal info --pool RBD_HDD --image 2ef34a96-27e0-4ae7-9888-fd33c38f657a
rbd: journaling is not enabled for image 2ef34a96-27e0-4ae7-9888-fd33c38f657a
:~# rbd feature enable RBD_HDD/2ef34a96-27e0-4ae7-9888-fd33c38f657a journaling --journal-pool RBD_SSD
:~# rbd journal info --pool RBD_HDD --image 2ef34a96-27e0-4ae7-9888-fd33c38f657a
rbd journal '37c8974b0dc51':
header_oid: journal.37c8974b0dc51
object_oid_prefix: journal_data.1.37c8974b0dc51.
order: 24 (16384 kB objects)
splay_width: 4
***************<NOTE NO object_pool> ****************
:~# rbd info RBD_HDD/2ef34a96-27e0-4ae7-9888-fd33c38f657a
rbd image '2ef34a96-27e0-4ae7-9888-fd33c38f657a':
size 51200 MB in 12800 objects
order 22 (4096 kB objects)
block_name_prefix: rbd_data.37c8974b0dc51
format: 2
features: layering, exclusive-lock, object-map, fast-diff, deep-flatten, journaling
flags:
create_timestamp: Sat May 5 11:39:07 2018
journal: 37c8974b0dc51
mirroring state: disabled
Kind regards,
Glen Baars
From: Jason Dillaman <jdillama@xxxxxxxxxx>
Sent: Tuesday, 14 August 2018 12:04 AM
To: Glen Baars <glen@xxxxxxxxxxxxxxxxxxxxxx>
Cc: dillaman <dillaman@xxxxxxxxxx>; ceph-users <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: [ceph-users] RBD journal feature
Hello Jason,
Interesting, I used ‘rados ls’ to view the SSDPOOL and can’t see any objects. Is this the correct way to view the journal objects?
You won't see any journal objects in the SSDPOOL until you issue a write:
$ rbd create --size 1G --image-feature exclusive-lock rbd_hdd/test
$ rbd bench --io-type=write --io-pattern=rand --io-size=4K --io-total=16M rbd_hdd/test --rbd-cache=false
bench type write io_size 4096 io_threads 16 bytes 16777216 pattern random
SEC OPS OPS/SEC BYTES/SEC
10 3520 356.04 1458356.70
11 3920 361.34 1480050.97
elapsed: 11 ops: 4096 ops/sec: 353.61 bytes/sec: 1448392.06
$ rbd feature enable rbd_hdd/test journaling --journal-pool rbd_ssd
$ rbd journal info --pool rbd_hdd --image test
rbd journal '10746b8b4567':
header_oid: journal.10746b8b4567
object_oid_prefix: journal_data.2.10746b8b4567.
order: 24 (16 MiB objects)
$ rbd bench --io-type=write --io-pattern=rand --io-size=4K --io-total=16M rbd_hdd/test --rbd-cache=false
bench type write io_size 4096 io_threads 16 bytes 16777216 pattern random
SEC OPS OPS/SEC BYTES/SEC
elapsed: 16 ops: 4096 ops/sec: 245.04 bytes/sec: 1003692.81
$ rados -p rbd_ssd ls | grep journal_data.2.10746b8b4567.
journal_data.2.10746b8b4567.3
journal_data.2.10746b8b4567.0
journal_data.2.10746b8b4567.2
journal_data.2.10746b8b4567.1
rbd feature enable SLOWPOOL/RBDImage journaling --journal-pool SSDPOOL
The symptoms that we are experiencing is a huge decrease in write speed ( 1QD 128K writes from 160MB/s down to 14MB/s ). We see no improvement when moving the
journal to SSDPOOL ( but we don’t think it is really moving )
If you are trying to optimize for 128KiB writes, you might need to tweak the "rbd_journal_max_payload_bytes" setting since it currently is defaulted to split journal write events
into a maximum of 16KiB payload [1] in order to optimize the worst-case memory usage of the rbd-mirror daemon for environments w/ hundreds or thousands of replicated images.
Kind regards,
Glen Baars
From: Jason Dillaman <jdillama@xxxxxxxxxx>
Sent: Saturday, 11 August 2018 11:28 PM
To: Glen Baars <glen@xxxxxxxxxxxxxxxxxxxxxx>
Cc: ceph-users <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: [ceph-users] RBD journal feature
Hello Ceph Users,
I am trying to implement image journals for our RBD images ( required for mirroring )
rbd feature enable SLOWPOOL/RBDImage journaling --journal-pool SSDPOOL
When we run the above command we still find the journal on the SLOWPOOL and not on the SSDPOOL. We are running 12.2.7 and all bluestore. We have also tried the
ceph.conf option (rbd journal pool = SSDPOOL )
Has anyone else gotten this working?
The journal header was on SLOWPOOL or the journal data objects? I would expect that the journal metadata header is located on SLOWPOOL but all data objects should be created on
SSDPOOL as needed.
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