Use same L2 Cache for dual boot

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bo3bber
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Use same L2 Cache for dual boot

Post by bo3bber »

I don't understand why I am unable to use the same L2 Cache for a dual boot system.

If I have two partitions both setup to use PrimoCache, I would like to have them both use the same L2 Cache and caching strategy for a third large volume.

If both boot disks see the exact same L2 Cache, then there is no corruption or conflict for the other boot. Because it would always be up to date relative to the backing disk for either side.


When I try to set it up this way, the L2Cache is visible to the other boot, but not selectable.
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Re: Use same L2 Cache for dual boot

Post by Support »

Theoretically it is possible to use same L2 cache for same drives in dual boot systems. However, in order to avoid using incorrect/corrypted or "out of sync" L2 cache data, PrimoCache uses certain mechanisms to detect L2 cache status, including store and verify Windows boot/shutdown status to check if last time Windows was ungracefully shutdown. For dual boot systems, their boot/shutdown status are not same.
However, we do have the plan to support this feature in future. Thanks.
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Jolly
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Re: Use same L2 Cache for dual boot

Post by Jolly »

Could you document how you detect the cache status, where you store the info in the registry, etc?
It may be possible to enable the dual boot scenario with clever use of REG_LINK's.


If there is not a way to dual boot and use the L2 cache, is there a way to prevent dual booting from invalidating the cache? (By disabling access to the cached drive in the dual boot install).

I have two windows installs, one my primary, the second a vhdx boot drive that I use for games/testing software. (The VHDX boot makes it very simple to rollback any changes, and segregate my work from play).

The VHDX boot does not need access to the cached drive.
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Re: Use same L2 Cache for dual boot

Post by Support »

It is not only relying on the registry information, but also the target cache task GUID. Each cache task has a different GUID.
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Jolly
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Re: Use same L2 Cache for dual boot

Post by Jolly »

Any more details? Is it possible to not invalidate L2 cache if you only use it as a read cache? I'm really only using that drive for games/movies, so I'm not concerned about data loss.
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Re: Use same L2 Cache for dual boot

Post by Support »

You may have seen that there is a unique GUID assigned to each cache task, in a form like {xxxxxxxx-xxxxxxxx-xxxxxxxx-xxxxxxxx}, where x is any hex digits. Each cache task's GUID is different and L2 cache will verify this GUID. So it will see the cache task in another OS is not the target cache task.

I think there is a trick to solve this problem. In one Windows OS, after you create a cache task, then open the registry editor and go to the branch HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\FancyCcV\Repository, export this registry branch. In the other Windows OS, you import this registry setting. Thus in these two OSes, you will have two identical cache tasks.
Of course, you still need to enable "Ignore Sync Check" in the cache setting.
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