Hmm...Not *true* in my setup and in fact this can't be true with Ceph..Ceph's WA should be ~2.3 -2.4 considering journal write, excluding journal write it should be well below 1.
Single OSD , journal (10G) and data on the same SSD but in different partitions..1 rbd image with 200G..
root@emsnode10:~/sjust# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 304G 168G 121G 59% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
udev 32G 12K 32G 1% /dev
tmpfs 6.3G 1.3M 6.3G 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 32G 8.0K 32G 1% /run/shm
none 100M 0 100M 0% /run/user
/dev/sdj2 7.0T 201G 6.8T 3% /var/lib/ceph/osd/ceph-0
root@emsnode10:~/sjust# ceph df
GLOBAL:
SIZE AVAIL RAW USED %RAW USED
7141G 6941G 200G 2.80
POOLS:
NAME ID USED %USED MAX AVAIL OBJECTS
rbd 1 200G 2.80 6941G 51203
Must be something we are missing in your case.
Thanks & Regards
Somnath
-----Original Message-----
From: ceph-devel-owner@xxxxxxxxxxxxxxx [mailto:ceph-devel-owner@xxxxxxxxxxxxxxx] On Behalf Of James (Fei) Liu-SSI
Sent: Friday, February 26, 2016 9:47 AM
To: ceph-devel@xxxxxxxxxxxxxxx
Subject: Ceph space amplification ratio with write is more than 2
Hi Cepher,
We recently have tested the Ceph space amplification with filestore through writing data to ramdisk with rados bench. However, we found only
3584 MB was written from rados bench but totally 8658M(1G of total 9G of ramdisk was used for journal) was used in the ramdisk.
The totally space amplification is 7658/3584 = 2.14. (It is surprising huge factor) 1. Cluster configuration:
. One OSD and one MON are in the same machine with rados bench. Replication factor was set as 1.
. ceph version from ceph master 5979c8e34fa2f3d7efa28c29fb90758b3f9f818 (45979c8e34fa2f3d7efa28c29fb90758b3f9f818)
2. Rados command we have been used :
rados bench -p rbd -b 4096 --max-objects 1048576 300 write --no-cleanup 3. ceph cluster configuration:
Please see appendix 1.
4. Results investigation.
Please see appendix 0.
Could anyone help to explain why the space amplification with filestore is huge? Thanks a lot.
Regards,
James
Appendix 0:
ssd@OptiPlex-9020-1:~/src/bluestore$ ceph df
GLOBAL:
SIZE AVAIL RAW USED %RAW USED
9206M 547M 8658M 94.05
POOLS:
NAME ID USED %USED MAX AVAIL OBJECTS
rbd 0 3584M 38.93 547M 917505 ssd@OptiPlex-9020-1:~/src/bluestore$ ceph -s
cluster a7f64266-0894-4f1e-a635-d0aeaca0e993
health HEALTH_WARN
1 near full osd(s)
monmap e1: 1 mons at {localhost=127.0.0.1:6789/0}
election epoch 3, quorum 0 localhost
osdmap e7: 1 osds: 1 up, 1 in
flags sortbitwise
pgmap v31: 64 pgs, 1 pools, 3584 MB data, 896 kobjects
8658 MB used, 547 MB / 9206 MB avail
64 active+clean
ssd@OptiPlex-9020-1:~/src/bluestore$ df -h Filesystem Size Used Avail Use% Mounted on
/dev/sda2 2.7T 1.4T 1.2T 55% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup udev 5.9G 4.0K 5.9G 1% /dev tmpfs 1.2G 720K 1.2G 1% /run none 5.0M 0 5.0M 0% /run/lock none 5.9G 81M 5.8G 2% /run/shm none 100M 20K 100M 1% /run/user
/dev/ram1 9.0G 8.4G 618M 94% /home/ssd/src/bluestore/ceph-deploy/osd/myosddata
Journal size:
-rw-r--r-- 1 ssd ssd 37 Feb 25 15:53 ceph_fsid drwxr-xr-x 132 ssd ssd 4096 Feb 25 15:53 current
-rw-r--r-- 1 ssd ssd 37 Feb 25 15:53 fsid
-rw-r--r-- 1 ssd ssd 21 Feb 25 15:53 magic
-rw-r--r-- 1 ssd ssd 1073741824 Feb 25 15:53 myosdjournal
-rw-r--r-- 1 ssd ssd 6 Feb 25 15:53 ready
-rw-r--r-- 1 ssd ssd 4 Feb 25 15:53 store_version
-rw-r--r-- 1 ssd ssd 53 Feb 25 15:53 superblock
-rw-r--r-- 1 ssd ssd 10 Feb 25 15:53 type
-rw-r--r-- 1 ssd ssd 2 Feb 25 15:53 whoami
du -sh
It shows current use 8G.
Appendix 1:
[global]
fsid = a7f64266-0894-4f1e-a635-d0aeaca0e993
auth_cluster_required = none
auth_service_required = none
auth_client_required = none
filestore_xattr_use_omap = true
filestore_max_sync_interval=10
filestore_fd_cache_size = 64
filestore_fd_cache_shards = 32
filestore_op_threads = 6
filestore_queue_max_ops=5000
filestore_queue_committing_max_ops=5000
journal_max_write_entries=1000
journal_queue_max_ops=3000
filestore_wbthrottle_enable=false
filestore_queue_max_bytes=1048576000
filestore_queue_committing_max_bytes=1048576000
journal_max_write_bytes=1048576000
journal_queue_max_bytes=1048576000
osd_journal_size = 1024
debug_lockdep = 0/0
debug_context = 0/0
debug_crush = 0/0
debug_buffer = 0/0
debug_timer = 0/0
debug_filer = 0/0
debug_objecter = 0/0
debug_rados = 0/0
debug_rbd = 0/0
debug_journaler = 0/0
debug_objectcatcher = 0/0
debug_client = 0/0
debug_osd = 0/0
debug_optracker = 0/0
debug_objclass = 0/0
debug_filestore = 0/0
debug_journal = 0/0
debug_ms = 0/0
debug_monc = 0/0
debug_tp = 0/0
debug_auth = 0/0
debug_finisher = 0/0
debug_heartbeatmap = 0/0
debug_perfcounter = 0/0
debug_asok = 0/0
debug_throttle = 0/0
debug_mon = 0/0
debug_paxos = 0/0
debug_rgw = 0/0
debug_newstore = 0/0
debug_keyvaluestore = 0/0
osd_tracing = true
osd_objectstore_tracing = true
rados_tracing = true
rbd_tracing = true
osd_mount_options_xfs = rw,noatime,inode64,logbsize=256k,delaylog
osd_mkfs_options_xfs = -f -i size=2048
osd_op_threads = 32
objecter_inflight_ops=102400
ms_dispatch_throttle_bytes=1048576000
objecter_infilght_op_bytes=1048576000
osd_mkfs_type = xfs
osd_client_message_size_cap = 0
osd_client_message_cap = 0
osd_enable_op_tracker = false
mon_initial_members = localhost
mon_host = 127.0.0.1
mon data = '$CEPH_DEPLOY'/mon/mymondata
mon cluster log file = '$CEPH_DEPLOY'/mon/mon.log keyring='$CEPH_DEPLOY'/ceph.client.admin.keyring
run dir = '$CEPH_DEPLOY'/run
[osd.0]
osd data = '$CEPH_DEPLOY'/osd/myosddata
osd journal = '$CEPH_DEPLOY'/osd/myosddata/myosdjournal
#osd journal = '$WORKSPACE'/myosdjournal/myosdjournal
log file = '$CEPH_DEPLOY'/osd/osd.log'
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