Option to disable l1 ram cache and only use l2 cache Topic is solved

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kio80
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Option to disable l1 ram cache and only use l2 cache

Post by kio80 »

You should add a function to disable the L1 ram cache and only use the l2 cache.

This may seem odd but consider my scenario and you'll see it can be very useful. I use a small ssd for boot but most of my applications and data is on an iscsi volume. While gigabit is fast and the SAN with the iscsi volume is fast, the lan is a bottleneck when loading games or large applications. So having a local ssd cache is a tremendous advantage since the computer no longer has to pull objects from the lan.

Currently I'm using primocache with a very small ram cache, Only 128mb, and with the l2 cache filling an entire 60 gb ssd. It works but I'd like to be able to disable the ram cache entirely.
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Re: Option to disable l1 ram cache and only use l2 cache

Post by Support »

We'll consider it. Thanks.
stoneym
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Re: Option to disable l1 ram cache and only use l2 cache

Post by stoneym »

I don't see the point in disabling the ram cache. It is much faster than an SSD, located on a different bus, and can only make things faster. Why eliminate it?

Your scenario does not make it clear at all why this would be a good idea. In fact, being so dependent upon an iSCSI disk store would prompt me to create the largest L1 cache I possibly could to speed up my performance and remove network traffic.

I think the developers time would be better spent on other endeavors. Optimizing performance, creating new cache management algorithms, etc.
kio80
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Re: Option to disable l1 ram cache and only use l2 cache

Post by kio80 »

L1 cache is not preserved on reboot/shutdown. So every time the computer is started the objects will need to be fetched again from the remote array.

The idea is to only have to pull the objects once and have a local copy on the ssd for all subsequent uses of the application.
senoctar
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Re: Option to disable l1 ram cache and only use l2 cache

Post by senoctar »

You can set the ram cache to the minimum of 64MB, maybe the limit could be disabled or lowered enough not to matter (though I would say 64 is small enough).
Still, PrimoCache will take up RAM as overhead for maintaining the mapping for L2 cache. If you have a big cache and small block size, this will eat up much more than 128Mb.
matty72
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Re: Option to disable l1 ram cache and only use l2 cache

Post by matty72 »

I too would like the option to disable RAM caching altogether.
My interest is gaining network performance by using an SSD drive to saturate my Gigabit network when possible (All client computer rely on my server).
Like a previous post, I want any Cache to stick permanently which SSD only cache would achieve.

RAM Cache is great, and the way to go for the vast majority of users, but, why not make RAM / SSD usage selectable? I.e. RAM only, SSD only or RAM / SSD.
stenrulz
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Re: Option to disable l1 ram cache and only use l2 cache

Post by stenrulz »

After thinking about this feature i do think it would be a valid function, great for testing issues out.
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Re: Option to disable l1 ram cache and only use l2 cache

Post by Support »

Add this feature in version 0.9.8
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