[root@beta.zone1.node1 ~]#/opt/MegaRAID/MegaCli/MegaCli64 -cfgdsply -aall | grep Policy:
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
[root@beta.zone1.node1 ~]#/opt/MegaRAID/MegaCli/MegaCli64 -LdSetProp WB -Lall -aAll
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 0 (target id: 0) success
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 1 (target id: 1) success
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 2 (target id: 2) success
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 3 (target id: 3) success
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 4 (target id: 4) success
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 5 (target id: 5) success
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 6 (target id: 6) success
Learn cycle is active currently
So policy Change to WB will not come into effect immediately
Set Write Policy to WriteBack on Adapter 0, VD 7 (target id: 7) success
Exit Code: 0x00
[root@beta.zone1.node1 ~]#/opt/MegaRAID/MegaCli/MegaCli64 -cfgdsply -aall | grep Policy:
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
Default Cache Policy: WriteBack, ReadAhead, Cached, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU
raid卡进入学习周期。以上是手动执行megacli命令查询到的结果。
lsi megaraid每过一段时间（一般为1个月或3个月）进行放电和充电一次，进行电池校准以延长电池的使用寿命。
每次学习周期时间的长短要看电池充放电的速度，一般几个小时到几十个小时不等。
在学习周期期间raid卡会自动将缓存策略设置为WriteThrough, ReadAhead, Cached, No Write Cache if Bad BBU，并且不能被设置成WriteBack，会导致性能有所下降。
使用lich.node --disk_check --cache 会打印Learn cycle is active
currently，So policy Change to WB will not come into effect
immediately（目前是学习周期，设置可能暂时不会生效）
crontab 中自动执行的 lich.node --disk_check
--cache则会在/opt/mds/log/disk_cache.log中记录Learn cycle is active
currently，So policy Change to WB will not come into effect immediately
使用lich.node --disk_check --json查看时会有一个cache_stat字段 标示为：“Learn” .其它情况暂时标示为“Unknow”
