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October 20th, 2009 08:00
What does a really high RG utilization % indicate?
So as I understand, utilization % refers to what portion of time the disks in the RG are busy, that is in a given period of time (let's say 1 hour), utilization % refers to the % of time the disks were constantly in use.
I have a SATA RG in RAID 5 that has a 96% utilization rate. The RG has 13 disks of 1 TB each. Is this a really high utilization rate? Does this indicate an issue, or does this indicate that we are utilizing the RG to its full potential?
Some other numbers:
Queue Length: between 6 and 8.
Total IOPS: between 600 and 700.
How does one calculate what a RG is capable of in terms of IOPS?
I have a SATA RG in RAID 5 that has a 96% utilization rate. The RG has 13 disks of 1 TB each. Is this a really high utilization rate? Does this indicate an issue, or does this indicate that we are utilizing the RG to its full potential?
Some other numbers:
Queue Length: between 6 and 8.
Total IOPS: between 600 and 700.
How does one calculate what a RG is capable of in terms of IOPS?
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jps00
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October 20th, 2009 08:00
That depends.
You really have to specify the details of your workload and the needed response time for a good answer.
If you're doing single-threaded, large-block, sequential I/O with no bursty behavior. The short answer is, no. Otherwise, "It depends."
The White paper: EMC CLARiiON Best Practices for Performance and Availability, FLARE Revision 28.5 discusses RAID group utilization in its RAID groups section. It also describes how to calculate RAID group IOPs in its Sizing and Performance Planning section. This document is available on PowerLink.
RRR
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October 21st, 2009 02:00
An RG of 13 disks should be able to do 13 x about 75 IOps = 975 IOps, but it all depends on the I/O size as well, so it depends on what your IO pattern is.
RRR
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October 21st, 2009 02:00