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VMAX 20K - FE IOPS and Performance Metrics
Hi All,
I have few questions on VMAX performance metrics, please guide me to understand.
1. What is the maximum IOPS a single VMAX 20K FE port can handle?
1a) If it depends on the type of IO such as read hit, read miss, overwrite data in cache, and write to new slot, which factors determine whether it is a read miss or hit? Is it Enginuity?
2. If 2 ports of a FE going to share the same cpu core resource, will it make a difference using only one FE port i.e can that front end will be able to use all 100% of CPU resource?
3. When response time is considered, which element's response time really matter to application point of view? FE response time or disk group/BE respose time for read hit, read miss and write?
Thanks
Dino
PedalHarder
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September 14th, 2014 17:00
As usual, the answer to most performance related questions are... it depends!!
For a single port IOPS, the highest IO rate can be obtained from 100% read hit on small IO. Factors that reduce the IO rate from highest potential are:
- Hit vs. miss.
- IO size
- write ratio.
Miss, write and larger IO size all have overheads that take a little longer to complete, so the IO rate drops off.
With port sharing, both ports share the CPU - not recommended to have the same application use both ports. For the most predictable performance, using one port is better.
Every element in the IO life cycle adds up to produce the response time that an application experiences. When the application is satisfied with the performance, then all is good.... If performance is considered to be not acceptable, it can be any or multiple points along the way that might have the opportunity to be tuned. An investigation would be required to determine the best course of action.
Quincy561
1.3K Posts
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September 14th, 2014 18:00
There are 4 basic types of IO the FA can service
Read where data is in cache
Read where data is not in cache and the FA must put in a request for the data from the DA
Write where data is already marked WP in cache and not yet destaged
Write where the data is not in cache
I mention all 4 in my best practices presentation which is recorded and can be watched on EMC World web site. Just go to the virtual EMC World, put in some email address ( I've found any correctly formatted one works, like a@b.com ) then sort the sessions by most liked or most viewed, and it should be the first one.
12122
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September 15th, 2014 17:00
Thanks a lot guys, I will watch it and still if I have questions we ll discuss.