一、性能相关中继器

write-behind, read-ahead, io-cache, quick-read, open-behind, stat-prefetch(md-cache), io-threads(默认server端)

以上中继器默认全部开启，symlink-cache默认关闭。


NFS相关性能优化中继器

默认开启：

performance.nfs.write-behind

默认关闭：

performance.nfs.read-ahead

performance.nfs.io-cache

performance.nfs.quick-read

performance.nfs.stat-prefetch

performance.nfs.io-threads

performance.force-readdirp

二、默认配置及默认值

1、默认配置中继

在./vols/tank/tank-fuse.vol（客户端）文件中，默认会配置如下中继器：

dht和性能相关的write-behind, read-ahead, io-cache, quick-read, open-behind, stat-prefetch(md-cache).

 

在./vols/tank/tank.node1.data-disk3.vol同类（服务器端）文件中，默认会设置如下中继器参数：

posix、access-control、locks、io-threads、index、maker

2、默认配置项值

cache-size

io-cahce：cache-size：默认32MB

Size of the read cache

quick-read：cache-size：默认128MB

Size of the read cache

gluster volume set tank cache-size 32MB

该命令导致的cache-size更新包含两个部分，一个是io-cache里对应的cache大小，一个是quick-read里的cache大小。

从源代码上看，这两个cache-size对应同一个key，所以会出现一改全改的现象，应该是一个bug。

read-ahead：page-count：默认值4

key为performance.read-ahead-page-count，可以通过该选项进行设置。

gluster volume set tank read-ahead-page-count 4

Number of pages that will be pre-fetched

write-behind："cache-size"或者"window-size"：默认值1MB

key为performance.write-behind-window-size，可以通过该选项进行设置。

gluster volume set tank write-behind-window-size 1MB

Size of the write-behind buffer for a single file (inode).

io-threads：thread-count：默认16

key：performance.io-thread-count

gluster volume set tank io-thread-count 16

Number of threads in IO threads translator which perform concurrent IO operations at a given time

该配置保存在/vols/tank/tank.node1.data-disk3.vol同类文件中。

md-cache：md-cache-timeout：默认值1（亦stat-prefetch）

gluster volume set tank md-cache-timeout 1

该操作会更改md-cache中继器md-cache-timeout选项的默认值

Time period after which cache has to be refreshed

io-cache：cache-timeout：默认值1

key：performance.cache-refresh-timeout

gluster volume set tank cache-refresh-timeout 1

cache-timeout：The cached data for a file will be retained till 'cache-refresh-timeout' seconds, after which data re-validation is performed.


备注：默认参数基于GlusterFS 3.4.5