PrimoCache writes more L2 cache than the volume is big

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npelov
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PrimoCache writes more L2 cache than the volume is big

Post by npelov »

Hi,

Primocache still has one big problem. If I forget to pause/freeze the cache and I copy big files (in this case 300GB) Even though the L2 cache volume is only 100GB and at the end of file copy 30 GB were written to L2 cache it kept going and wrote >300 GB to the 100 GB partition. it would be nice to remove the data from L2 write queue if it won't fit in L2 cache.

Code: Select all

| written |                                              Pending                             |
|         |  no point of writing this part - it'll be overwritten        |   Will fit in L2  |

In fewer words there is no point to keep more than 100 GB in L2 write queue when the volume itself is 100GB

I hope it's clear enough what I mean.
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Support
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Re: PrimoCache writes more L2 cache than the volume is big

Post by Support »

In this case, your L2 is used as read cache, right? We have noticed this problem. However, the solution is not as simple as expected because L2 population is asynchronous and cache replacement algorithm requires data replacement. Anyway, we will try to find a solution to solve this problem.
Thank you.
Nick7
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Re: PrimoCache writes more L2 cache than the volume is big

Post by Nick7 »

Solution is somewhat simple.
When reading queue for what needs to be written in L2 grows.
If queue > L2 size, just trim whatever oldest is meant to be written in from queue.
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