Blackburn, James M (Jim) Jr. CIV USARMY PEO EIS (US) wrote:It all depends on what the definition of 'has a place' is.
Classification: UNCLASSIFIED
Caveats: NONE
If "NVRAM has no place in the IO operation of a filer", why doesn't every
NetApp storage system have the same amount of NVRAM/NVMEM?
I'd argue that the NVRAM is involved in the I/O operation of a Filer.
Putting copies of data (which sits in RAM) into NVRAM, mucking about with it (to keep it 100% consistent at all times in case of something sinister happening at *any* time!), and making sure it's emptied out etc etc kindof puts it in the I/O path w.r.t. capacity. It's an internal limiting factor inside the ONTAP kernel so...
The size of the NVRAM is effectively limited by the desired cluster pair failover time. The contents have to to be mirrored across the CI link all the time as well. It's an optimisation problem, like so many other things inside a storage system of the complexity that a FAS box has
In the coming new hi-end FAS models (not before early 2014 is my guess), the NVRAM will be larger than now due to other things mitigating the increasing failover time. (It's a whole new HW platform.)
/M
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Michael Bergman
Sr Systems Analyst / Storage Architect
Engineering Hub Stockholm Phone +46 10 7152945
Service Delivery, Engineering EMEA N SMS/MMS +46 70 5480835
Ericsson Torshamnsg 33, 16480 Sthlm, Sweden
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