PrimoCache skips L2-Cache on writes

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protator
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PrimoCache skips L2-Cache on writes

Post by protator »

This is the first time setting up a L2-Cache on my current workstation (and since I updated from 2.6 to 3.0.9)...

and I noticed that the L2-Cache I set up for my scrub disk isn't used for writes. Ever.
It prefetches/caches data from the hdd even with L2 set to 100%write/0%read, but when it's time to flush the L1 cache - be it due to cache overflow or the set interval - the data goes straight to the slow hdd instead of the SSD.

And to make matters worse, whenever PrimoCache prefetches data from the hdd, it doesn't pause the prefetching when it writes data from L1 to the disk. Or the other way round.
Result: godawful noises from the hdd and basicly no access to my files for minutes until PrimoCache is done running in circles.
Setting it to "on idle only" doesn't help. Once it starts gathering data it won't stop until it's done and completely ignores write access from the user and even itself.

I bought this software to protect my drives, not kill them prematurely.
PrimoCache has been around for a long time so I assume it's rather me doing something wrong than a bug at work.

How can I set the L2-Cache up as write-cache/buffer only w/o the prefetching.
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Re: PrimoCache skips L2-Cache on writes

Post by Support »

Prefetch feature is for L1 cache (RAM cache) only. L2 cache don't need the prefetch because L2 cache content is persistent across computer reboots.
Could you upload a screenshot of your PrimoCache main dialog which shows the cache configuration and status?
protator
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Re: PrimoCache skips L2-Cache on writes

Post by protator »

But that's the thing ... the L2 cache does gather data from the hdd after every read access. It "prefetches" recently accessed data from the drive it's supposed to be a write-cache for.

An example: With all deferred data flushed and caches reset L1 and L2 show 24 and 238 Gb free. So far do good. Both caches set to "write only".
Now I copy a 20Gb file from the harddrive to a RAM drive ... wait until the transfer is complete and do nothing else.
After a minute or so TaskManager shows read access on the hdd again and when I check the cache task I can watch the L2 cache slowly tick down for the next couple minutes until it's down to ... 218 Gb. "Total Write(Req)"=0KB. L1 is also still empty.
If this was tiered storage I'd understand why it'd move recently/frequently accessed data to the faster storage devices, that'd be the whole point, ... but PrimoCache and with these settings? Just: Why?
Am I completely misunderstanding the way L2 is implemented?
All I want is a persistent cache layer to secure data from L1 quickly even if the cached drive is old and slow.
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Re: PrimoCache skips L2-Cache on writes

Post by Support »

Was there another volume assigned to the cache task? Or did you see that the Total Read increased about 20GB?
When the cache strategy is write-only, reading files shall not occupy the cache space.
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