My experience is performance degrades dramatically when dirty objects are flushed.
Best Regards,
Wade
On Fri, Jan 8, 2016 at 11:08 AM hnuzhoulin <hnuzhoulin2@xxxxxxxxx> wrote:
Hi,guyes
Recentlly,I am testing cache-tier using writeback mode.but I found a
strange things.
the performance using rados bench degrade.Is it correct?
If so,how to explain.following some info about my test:
storage node:4 machine,two INTEL SSDSC2BB120G4(one for systaem,the other
one used as OSD),four sata as OSD.
before using cache-tier:
root@ceph1:~# rados bench -p coldstorage 300 write --no-cleanup
----------------------------------------------------------------
Total time run: 301.236355
Total writes made: 6041
Write size: 4194304
Bandwidth (MB/sec): 80.216
Stddev Bandwidth: 10.5358
Max bandwidth (MB/sec): 104
Min bandwidth (MB/sec): 0
Average Latency: 0.797838
Stddev Latency: 0.619098
Max latency: 4.89823
Min latency: 0.158543
root@ceph1:/root/cluster# rados bench -p coldstorage 300 seq
Total time run: 133.563980
Total reads made: 6041
Read size: 4194304
Bandwidth (MB/sec): 180.917
Average Latency: 0.353559
Max latency: 1.83356
Min latency: 0.027878
after configure cache-tier:
root@ubuntu:~/benchmarkcollect/Monitor# ceph osd tier add coldstorage
hotstorage
pool 'hotstorage' is now (or already was) a tier of 'coldstorage'
root@ubuntu:~/benchmarkcollect/Monitor# ceph osd tier cache-mode
hotstorage writeback
set cache-mode for pool 'hotstorage' to writeback
root@ubuntu:~/benchmarkcollect/Monitor# ceph osd tier set-overlay
coldstorage hotstorage
overlay for 'coldstorage' is now (or already was) 'hotstorage'
oot@ubuntu:~# ceph osd dump|grep storage
pool 6 'coldstorage' replicated size 3 min_size 1 crush_ruleset 0
object_hash rjenkins pg_num 512 pgp_num 512 last_change 216 lfor 216 flags
hashpspool tiers 7 read_tier 7 write_tier 7 stripe_width 0
pool 7 'hotstorage' replicated size 3 min_size 1 crush_ruleset 1
object_hash rjenkins pg_num 128 pgp_num 128 last_change 228 flags
hashpspool,incomplete_clones tier_of 6 cache_mode writeback target_bytes
100000000000 hit_set bloom{false_positive_probability: 0.05, target_size:
0, seed: 0} 3600s x6 stripe_width 0
-------------------------------------------------------------
rados bench -p coldstorage 300 write --no-cleanup
Total time run: 302.207573
Total writes made: 4315
Write size: 4194304
Bandwidth (MB/sec): 57.113
Stddev Bandwidth: 23.9375
Max bandwidth (MB/sec): 104
Min bandwidth (MB/sec): 0
Average Latency: 1.1204
Stddev Latency: 0.717092
Max latency: 6.97288
Min latency: 0.158371
root@ubuntu:/# rados bench -p coldstorage 300 seq
Total time run: 153.869741
Total reads made: 4315
Read size: 4194304
Bandwidth (MB/sec): 112.173
Average Latency: 0.570487
Max latency: 1.75137
Min latency: 0.039635
ceph.conf:
--------------------------------------------
[global]
fsid = 4ec1eb64-226c-4d90-8c5c-b6b6644be831
mon_initial_members = ceph2, ceph3, ceph4
mon_host = 10.**.**.241,10.**.**.242,10.**.**.243
auth_cluster_required = cephx
auth_service_required = cephx
auth_client_required = cephx
filestore_xattr_use_omap = true
osd_pool_default_size = 3
osd_pool_default_min_size = 1
auth_supported = cephx
osd_journal_size = 10240
osd_mkfs_type = xfs
osd crush update on start = false
[client]
rbd_cache = true
rbd_cache_writethrough_until_flush = false
rbd_cache_size = 33554432
rbd_cache_max_dirty = 25165824
rbd_cache_target_dirty = 16777216
rbd_cache_max_dirty_age = 1
rbd_cache_block_writes_upfront = false
[osd]
filestore_omap_header_cache_size = 40000
filestore_fd_cache_size = 40000
filestore_fiemap = true
client_readahead_min = 2097152
client_readahead_max_bytes = 0
client_readahead_max_periods = 4
filestore_journal_writeahead = false
filestore_max_sync_interval = 10
filestore_queue_max_ops = 500
filestore_queue_max_bytes = 1048576000
filestore_queue_committing_max_ops = 5000
filestore_queue_committing_max_bytes = 1048576000
keyvaluestore_queue_max_ops = 500
keyvaluestore_queue_max_bytes = 1048576000
journal_queue_max_ops = 30000
journal_queue_max_bytes = 3355443200
osd_op_threads = 20
osd_disk_threads = 8
filestore_op_threads = 4
osd_mount_options_xfs = rw,noatime,nobarrier,inode64,logbsize=256k,delaylog
[mon]
mon_osd_allow_primary_affinity=true
--
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