What are the “CacheHitRate” and “CacheHitRate” and “IOPS” Thresholds??

[daudsoomro]

Hi

 

We need to know what are the “CacheHitRate” and “CacheHitRate” and “IOPS” Thresholds?? /recommendation.

Because we are facing 100% read/write or more utilization in storage.

 

Storage: Fujitsu DX80 ISCSI 1Gbps Storage

Operating System: windows 2008 and windows 2012

 

For your reference:

[TABLE=width: 811]

[TR]

[TD]IOPS Read (IOPS)

[/TD]

[TD]IOPS Write (IOPS)

[/TD]

[TD]Data Rate Read (MB/S)

[/TD]

[TD]Data Rate Write (MB/S)

[/TD]

[TD]Response Time Read (mS)

[/TD]

[TD]Response Time Write (mS)

[/TD]

[TD]CacheHitRate Read (%)

[/TD]

[TD]CacheHitRate Write (%)

[/TD]

[TD]CacheHitRate Prefetch (%)

[/TD]

[/TR]

[/TABLE]

 

Regards,

MDS.

[Gatt]

High IOPS is bad i believe - that's the number of input/outputs operations per second. (IOPS - Wikipedia, the free encyclopedia)

The higher that is, the harder your drive is working, meaning it will wear it out quicker, and cause unnessesary read/write delays (slow performance)

 

CacheHitRatio will be the amount of data stored in temporary cache, due to the high IOPS - (data waiting to be written to or read from a disk). This can potentially be lost if the system fails.

 

Someone correct me if I'm wrong here?

[nicklec]

IOPs is a performance metric, high isn't bad ... it just means the disks are busy.

 

CacheHitRate (our HP SAN doesn't use this term) is probably data served from the cache (avoiding a disk IOP), which is a good thing.

 

If you're worried about 'utilization' then your latencies should remain low and not spike around (more IOPS than your disks can handle), not an exact science but i would expect under 20ms unless you have 7200rpm disks (not supposed to be used for high IOPS).