Re: Random/Sequential measurement on Filers

I usually describe NVRAM as a transaction log...

On 1/20/2014 11:33 PM, Jeff Mohler wrote:

PS: I think we just agreed. :)

But its good to make the hard point, that NVRAM is not part of a write. Its common to see it as such, but it's systemically more correct to never mention NVRAM when talking about writes..cuz it doesnt matter. Its just a protection.

On Mon, Jan 20, 2014 at 2:31 PM, Jeff Mohler <speedtoys.racing@gmail.com mailto:speedtoys.racing@gmail.com> wrote:

No..NVRAM is not in the actual path of a write IO to disk.

Writes go to system RAM, a copy is made to NVRAM, when the system
RAM space allocated is 1/2 full or the timer goes off..then writes
are made to disk and the NVRAM copy is discarded.

NVRAM is there, but not part of the IO path to disk, it is beside
it, and un-used unless the system crashed before RAM blocks were
fully committed to disk.


On Mon, Jan 20, 2014 at 2:26 PM, Michael Bergman
<michael.bergman@ericsson.com
<mailto:michael.bergman@ericsson.com>> wrote:

    Couldn't resist... (sorry)


    Jeff Mohler wrote:

        :s/NVRAM/System Memory/g

        Fixed it for ya.


    Shouldn't that be more like

    :s/NVRAM/System Memory plus a copy into NVRAM including mirror
    across to the HA cluster partners (if any) NVRAM, before
    returning with 'written OK'/g

    :-)

    /M

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