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jmaguileramontero
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February 14th, 2011 11:00
FAST CACHE CONFIGURATIONS
Hello everybody,
I have a CX4-120c, I´ve installed fast cache enabler and 2 100GB SSD disk. When I was configuring the fast cache, it show me this message:
And I have some questions:
1.- How long is this process considering that I have 2 disks ssd of 100 gb?
2.- The write cache and read cache will be disable during the process?
3.- This is the most important for me. Storage´s performance will not afected in this process?
Thank you very much.
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Posted February 14th, 2011 12:00
It can have a performance impact since it needs to disable your current cache in order to re-configure it for FASTCache. during taht time, you are not using cache and everything is coming/going straight to disk.
But your only doing 200G so i might be fast. if your worried about the performance, do it at night during low I/O.
All cache will be disabled for it to configure FASTCache.
364
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Posted February 15th, 2011 05:00
Thanks for your help.
364
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Posted February 16th, 2011 18:00
Remember that FAST Cache being configured will eat part of your current cache to be able to operate and store the memory map. Because of this, if you have any disk that is currently relying on cache (you shouldn't but still) you should know that the FAST Cache after installed is enabled by default on new LUNs but DISABLED on old LUNs. Hence if you are relying on the Cahce for a LUN or two now, you need to immediatly turn on FAST Cache for them.
christopher_ime
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1962 Posts
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Posted February 15th, 2011 01:00
Simply wanted to comment here that the size of the FAST Cache being added (EFD) is not the major factor and requires little time in comparison to the main consideration which is flushing what is currently in cache (RAM). So things to consider is certainly how busy the array is, how much cache (RAM) there is and of the write cache needs to be committed to the back-end (which as we all know has its own contribution to the overall time: raid type, disk type, I/O profile, etc.).