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30994
June 15th, 2007 08:00
PERC 5/i and MegaCli
Hi, I remote administer two dell poweredge 2950 with raid10 configuration on PERC 5/i RAID Controller. And on one of this servers i must rise a heavy write mysql 5.0.x server and i must optimise the raid controller configuration for that and i can only use MegaCli tool for monitoring and administration of this controller. Could someone please tell me how can I check if the raid Dell PERC 5/i RAID Controller has the cache policy set up on the write back by using the MegaCli ? As well, if it does not have this option set up how can I set it up by using the same MegaCli ? Here is some infos about my raid configuration admin@dell01:~# ./MegaCli -LDInfo -L0 -a0 | grep -i policy Default Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU Access Policy: Read/Write Disk Cache Policy: Disk's Default admin@dell01:~# ./MegaCli -AdpAllInfo -aAll | grep -i policy Write Policy : WB Read Policy : None admin@dell01:~# ./MegaCli -AdpAllInfo -aAll | grep -i cache Cache When BBU Bad : Disabled Cached IO : No
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cosmih
6 Posts
0
June 15th, 2007 08:00
Hi,
I remote administer two dell poweredge 2950 with raid10 configuration on PERC 5/i RAID Controller. And on one of this servers i must rise a heavy write mysql 5.0.x server and i must optimise the raid controller configuration for that and i can only use MegaCli tool for monitoring and administration of this controller.
Could someone please tell me how can I check if the raid Dell PERC 5/i RAID Controller has the cache policy set up on the write back by using the MegaCli ? As well, if it does not have this option set up how can I set it up by using the same MegaCli ?
Here is some infos about my raid configuration
admin@dell01:~# ./MegaCli -LDInfo -L0 -a0 | grep -i policy
Default Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU
Current Cache Policy: WriteThrough, ReadAheadNone, Direct, No Write Cache if Bad BBU
Access Policy: Read/Write Disk Cache Policy: Disk's Default
admin@dell01:~# ./MegaCli -AdpAllInfo -aAll | grep -i policy
Write Policy : WB
Read Policy : None
admin@dell01:~# ./MegaCli -AdpAllInfo -aAll | grep -i cache
Cache When BBU Bad : Disabled
Cached IO : No
DELL-GaryS
777 Posts
0
June 15th, 2007 20:00
Write Policy
Write Policy specifies the controller write policy. You can set the write policy to Write-Back or Write-Through.
In Write-Back caching, the controller sends a data transfer completion signal to the host when the controller cache has received all the data in a transaction.
NOTE: The default cache setting is Write-back cache.
NOTICE: If Write-back is enabled and the system is quickly turned off and then on, the controller may pause as the system flushes cache memory. Controllers that contain a battery backup will default to write-back caching.
In Write-Through caching, the controller sends a data transfer completion signal to the host when the disk subsystem has received all the data in a transaction.
NOTE: Certain data patterns and configurations perform better with Write-through cache policy.
Write-Back caching has a performance advantage over write-through caching.