Ceph Reef(18.2.X)之压缩算法和压缩模式

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正杰

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目录

• 一.ceph压缩概述
  • 1.ceph压缩概述
  • 2.启用压缩相关命令
• 二.ceph压缩案例
  • 1.查默认的压缩算法
  • 2.更改压缩算法
  • 3.更改算法模式
  • 4.还原算法和模式

一.ceph压缩概述

1.ceph压缩概述

ceph支持高效传输，支持对数据进行压缩，BluStrore存储引擎默认提供了即时数据压缩，以节省磁盘空间。

ceph支持none，zlib(不推荐)，lz4(和snappy性能接近)，zstd(压缩比高但耗费CPU)和snappy等常用的压缩方式，默认为snappy压缩算法。
	
ceph支持压缩模式有none，passive，aggressive，force，默认值为none。
	- none:
	    表示不压缩。
	- passive:
			若提示COMPRESSIBLE，则压缩。
	- aggressive:
  		除非提示INCOMPRESSIBLE，否则就压缩。
  - force:
  		表示始终压缩。

2.启用压缩相关命令

启用压缩的相关命令: (如果需要全局压缩，最好在配置文件中指定)
ceph osd pool set <pool_name> compression_algorithm snappy  # 指定压缩算法
ceph osd pool set <pool_name> compression_mode aggressive  # 指定压缩模式


其他可用的压缩参数:
    compression_required ratio:
    	指定压缩比，取值格式为双精度浮点型。
    	其值为"SIZE_COMPRESSED/SIZE_ORIGINAL"，即压缩后的大小与原始内容大小的比例，默认值为"0.875000"。
    
    compression_max_blob_size:
    	压缩对象的最大体积，无符号整数型数值，默认为0。
    	
    compression_min_blob_size:
    	压缩对象的最小体积，无符号整数型数值，默认值为0。
    

全局压缩选项:
	可在ceph配置文件中设置压缩属性，它将对所有的存储池生效，可设置相关参数如下:
		bluestore_compression_algorithm
		bluestore_compression_mode
		bluestore_compression_required_ratio
		bluestore_compression_min_blob_size
		bluestore_compression_max_blob_size
		bluestore_compression_min_blob_size_ssd
		bluestore_compression_max_blob_size_ssd
		bluestore_compression_min_blob_size_hdd
		bluestore_compression_max_blob_size_hdd

二.ceph压缩案例

1.查默认的压缩算法

[root@ceph141 ~]# ceph --admin-daemon /var/run/ceph/c0ed6ca0-5fbc-11ef-9ff6-cf3a9f02b0d4/ceph-osd.0.asok config show | grep compression
    "bluestore_compression_algorithm": "snappy",
    "bluestore_compression_max_blob_size": "0",
    "bluestore_compression_max_blob_size_hdd": "65536",
    "bluestore_compression_max_blob_size_ssd": "65536",
    "bluestore_compression_min_blob_size": "0",
    "bluestore_compression_min_blob_size_hdd": "8192",
    "bluestore_compression_min_blob_size_ssd": "65536",
    "bluestore_compression_mode": "none",
    "bluestore_compression_required_ratio": "0.875000",
    "bluestore_rocksdb_options": "compression=kLZ4Compression,max_write_buffer_number=64,min_write_buffer_number_to_merge=6,compaction_style=kCompactionStyleLevel,write_buffer_size=16777216,max_background_jobs=4,level0_file_num_compaction_trigger=8,max_bytes_for_level_base=1073741824,max_bytes_for_level_multiplier=8,compaction_readahead_size=2MB,max_total_wal_size=1073741824,writable_file_max_buffer_size=0",
    "filestore_rocksdb_options": "max_background_jobs=10,compaction_readahead_size=2097152,compression=kNoCompression",
    "kstore_rocksdb_options": "compression=kNoCompression",
    "leveldb_compression": "true",
    "mon_rocksdb_options": "write_buffer_size=33554432,compression=kNoCompression,level_compaction_dynamic_level_bytes=true",
    "ms_osd_compression_algorithm": "snappy",
    "rbd_compression_hint": "none",
[root@ceph141 ~]# 

2.更改压缩算法

[root@ceph141 ~]# ceph osd pool ls detail | grep yinzhengjie-rbd  # 默认不现实压缩算法
pool 2 'yinzhengjie-rbd' replicated size 3 min_size 2 crush_rule 0 object_hash rjenkins pg_num 16 pgp_num 16 autoscale_mode on last_change 63 flags hashpspool,selfmanaged_snaps stripe_width 0 application rbd read_balance_score 1.88
[root@ceph141 ~]# 
[root@ceph141 ~]# ceph osd pool set yinzhengjie-rbd compression_algorithm zstd  # 指定压缩算法
set pool 2 compression_algorithm to zstd
[root@ceph141 ~]# 
[root@ceph141 ~]# ceph osd pool ls detail | grep yinzhengjie-rbd  # 查看压缩算法是否生效
pool 2 'yinzhengjie-rbd' replicated size 3 min_size 2 crush_rule 0 object_hash rjenkins pg_num 16 pgp_num 16 autoscale_mode on last_change 344 flags hashpspool,selfmanaged_snaps stripe_width 0 compression_algorithm zstd application rbd read_balance_score 1.88
[root@ceph141 ~]# 

3.更改算法模式

[root@ceph141 ~]# ceph osd pool ls detail | grep yinzhengjie-rbd
pool 2 'yinzhengjie-rbd' replicated size 3 min_size 2 crush_rule 0 object_hash rjenkins pg_num 16 pgp_num 16 autoscale_mode on last_change 344 flags hashpspool,selfmanaged_snaps stripe_width 0 compression_algorithm zstd application rbd read_balance_score 1.88
[root@ceph141 ~]# 
[root@ceph141 ~]# ceph osd pool set yinzhengjie-rbd compression_mode aggressive
set pool 2 compression_mode to aggressive
[root@ceph141 ~]# 
[root@ceph141 ~]# ceph osd pool ls detail | grep yinzhengjie-rbd
pool 2 'yinzhengjie-rbd' replicated size 3 min_size 2 crush_rule 0 object_hash rjenkins pg_num 16 pgp_num 16 autoscale_mode on last_change 345 flags hashpspool,selfmanaged_snaps stripe_width 0 compression_algorithm zstd compression_mode aggressive application rbd read_balance_score 1.88
[root@ceph141 ~]# 

4.还原算法和模式

[root@ceph141 ~]# ceph osd pool ls detail | grep yinzhengjie-rbd
pool 2 'yinzhengjie-rbd' replicated size 3 min_size 2 crush_rule 0 object_hash rjenkins pg_num 16 pgp_num 16 autoscale_mode on last_change 345 flags hashpspool,selfmanaged_snaps stripe_width 0 compression_algorithm zstd compression_mode aggressive application rbd read_balance_score 1.88
[root@ceph141 ~]# 
[root@ceph141 ~]# 
[root@ceph141 ~]# ceph osd pool set yinzhengjie-rbd compression_mode none
set pool 2 compression_mode to none
[root@ceph141 ~]# 
[root@ceph141 ~]# ceph osd pool set yinzhengjie-rbd compression_algorithm snappy
set pool 2 compression_algorithm to snappy
[root@ceph141 ~]# 
[root@ceph141 ~]# ceph osd pool ls detail | grep yinzhengjie-rbd
pool 2 'yinzhengjie-rbd' replicated size 3 min_size 2 crush_rule 0 object_hash rjenkins pg_num 16 pgp_num 16 autoscale_mode on last_change 347 flags hashpspool,selfmanaged_snaps stripe_width 0 compression_algorithm snappy compression_mode none application rbd read_balance_score 1.88
[root@ceph141 ~]#