Bcache是Linux内核块层cache,它使用SSD来作为HDD硬盘的cache,从而起到加速作用。Bcache内核模块仅在Linux 3.10及以上版本支持,因此使用Bcache,需要将内核升级到3.10及以上版本,并在内核配置项中打开Bcache模块。
Bcache具有以下特征:
相关名词:
Bcache支持三种缓存策略:writeback(回写策略)、writethrough(写通策略)、writearound(旁路策略)。默认使用writethrough,缓存策略可动态修改。
要使用bcache,需要安装相关的工具包bcache-tools。
下载链接:https://git.kernel.org/pub/scm/linux/kernel/git/colyli/bcache-tools.git/snapshot/bcache-tools-1.1.tar.gz
将下载的bcache-tools上传到服务器/opt/
目录下
解压缩,切换工作目录
cd /opt/
tar -zxvf bcache-tools-1.1.tar.gz
cd bcache-tools-1.1/
安装依赖
yum install libblkid-devel -y
安装
make
make install
验证
pkg-config: not found
# Ubuntu apt install pkg-config
Package uuid was not found in the pkg-config search path.
Perhaps you should add the directory containing uuid.pc
to the PKG_CONFIG_PATH environment variable
No package ‘uuid’ found# Ubuntu apt install uuid-dev
Package blkid was not found in the pkg-config search path.
Perhaps you should add the directory containing blkid.pc
to the PKG_CONFIG_PATH environment variable
No package ‘blkid’ found# Ubuntu apt install libblkid-dev # CentOS yum install libblkid-devel
Package smartcols was not found in the pkg-config search path.
Perhaps you should add the directory containing `smartcols.pc’
to the PKG_CONFIG_PATH environment variable
No package ‘smartcols’ found# Ubuntu apt install libsmartcols-dev # CentOS yum install liblibsmartcols-devel
/dev/sdl
和/dev/sdx
是SSD设备,我们用/dev/sdl
这块SSD加速/dev/sda
和/dev/sdb
两块HDD。
make-bcache -B /dev/sda /dev/sdb -C /dev/sdl # 自动关联Bcache设备
或者
make-bcache -B /dev/sda /dev/sdb
make-bcache -C /dev/sdl
bcache attach /dev/sdl /dev/sda # 手动关联
bcache attach /dev/sdl /dev/sdb
[root@ceph01 ~]# bcache show -m
Name Uuid Cset_Uuid Type State Bname AttachToDev AttachToCset
/dev/sdb 12dee1f4-05ab-4e13-9262-dcea08dbfda0 354761ed-4f32-4064-8df3-3c74bbaf389b 1 (data)clean(running) bcache1 /dev/sdl 354761ed-4f32-4064-8df3-3c74bbaf389b
/dev/sdl f73a9156-8468-4001-b4ef-1ed508d34a08 354761ed-4f32-4064-8df3-3c74bbaf389b 3 (cacheactive N/A N/A N/A
/dev/sda e022596f-c813-46db-a48e-e7504065be31 354761ed-4f32-4064-8df3-3c74bbaf389b 1 (data)clean(running) bcache0 /dev/sdl 354761ed-4f32-4064-8df3-3c74bbaf389b
直接把/dev/bcache0
和/dev/bcache1
当做磁盘分区格式化挂载使用即可。
每一块低速盘(HDD)在经过make-bcache后,都会对应一个Bname,例如,bcache0、bcache1等。删除低速盘就是将对应的Bname设备停掉(删掉)。如果该Bname对应的设备有绑定前端盘(SSD),需要先解除与前端盘的关联。
# 获取后端设备的cset.uuid
[root@ceph01 ~]# bcache-super-show /dev/sda
sb.magic ok
sb.first_sector 8 [match]
sb.csum 44D5ED8229F0D21C [match]
sb.version 1 [backing device]
dev.label (empty)
dev.uuid e022596f-c813-46db-a48e-e7504065be31
dev.sectors_per_block 1
dev.sectors_per_bucket 1024
dev.data.first_sector 16
dev.data.cache_mode 0 [writethrough]
dev.data.cache_state 1 [clean]
cset.uuid 354761ed-4f32-4064-8df3-3c74bbaf389b
# 通过获取到的cset.uuid移除bcache0的绑定
[root@ceph01 ~]# echo 354761ed-4f32-4064-8df3-3c74bbaf389b > /sys/block/bcache0/bcache/detach
# 删除后端盘
[root@ceph01 ~]# echo 1 > /sys/block/bcache0/bcache/stop
[root@ceph01 ~]# ls /sys/fs/bcache/
354761ed-4f32-4064-8df3-3c74bbaf389b register register_quiet
# 取消前端高速缓存盘的注册
[root@localhost opt]# echo 1 >/sys/fs/bcache/354761ed-4f32-4064-8df3-3c74bbaf389b/unregister
[root@localhost opt]# make-bcache -B /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# 这是因为之前这块盘已经make-bcache过了, 可能出现在反复试验的时间, 多次创建、删除
[root@localhost opt]# make-bcache -B /dev/sdc --wipe-bcache
UUID: 3b3c8cd1-864b-4fdb-9283-a2e212d0d290
Set UUID: 92d8465a-0720-4b30-8f7d-988abdf3ee85
version: 1
block_size: 1
data_offset: 16
# 一个例子,/dev/sdb是前端缓存盘,/dev/sdc是后端数据盘
# 这个错误出现在我试验过程中, 在重新创建前端高速缓存设备的时间
# 这是因为前端高速缓存设备已经创建过了, 并未删除导致的
# 解决方法:
1. 查看ls /sys/fs/bcache/
2. 对前端缓存盘进行删除(取消注册)
[root@localhost opt]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdb 8:16 0 30G 0 disk
sdc 8:32 0 100G 0 disk
sda 8:0 0 20G 0 disk
├─sda2 8:2 0 19G 0 part
│ ├─centos-swap 253:1 0 2G 0 lvm [SWAP]
│ └─centos-root 253:0 0 17G 0 lvm /
└─sda1 8:1 0 1G 0 part /boot
[root@localhost opt]# make-bcache -C /dev/sdb
Can't open dev /dev/sdb: Device or resource busy
# 查看前端高速缓存设备注册信息?
[root@localhost opt]# ls /sys/fs/bcache/
0b241b68-c354-461d-9ca1-ea00448057a9 pendings_cleanup register register_quiet
# 由于当前系统是干净的, 但是/sys/fs/bcache/目录下存在注册信息, 应该是忘记删除导致的
# 对该注册信息进行删除(取消注册)
[root@localhost opt]# echo 1 >/sys/fs/bcache/0b241b68-c354-461d-9ca1-ea00448057a9/unregister
[root@localhost opt]# ls /sys/fs/bcache/
pendings_cleanup register register_quiet
# 重新创建前端高速缓存设备
[root@localhost opt]# make-bcache -C /dev/sdb --wipe-bcache
UUID: ba550b3f-646b-4740-8192-b9b2bebc3d63
Set UUID: f8361f22-92c3-421e-8a21-e5a5c6997508
version: 0
nbuckets: 61440
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
[root@localhost opt]# ls /sys/fs/bcache/
f8361f22-92c3-421e-8a21-e5a5c6997508 pendings_cleanup register register_quiet
鲲鹏BoostKit分布式存储使能套件-基础加速特性-Cache加速-Bcache用户指南-Bcache使用
Bcache官方用户文档
更多操作见:SSD加速HDD盘方案之bcache
bcache的使用