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Can I use an external SSD as cache?

Posted: Mon Aug 24, 2020 4:25 pm
by HotLasagna
Hello! I'm new to the forums, greetings!

I'd like to know if I can use PrimoCache to use an external SSD (connected via a USB 3.1 port or a USB 3.2 Thunderbolt port) as a cache to speed up my internal HDD.

I have a laptop, so I really can't just get an extra internal SSD and pop it in there. Because of warranty stuff, I can't replace the HDD itself either. So using an external SSD is my only potential option at the time.

Thanks in advance!

Re: Can I use an external SSD as cache?

Posted: Tue Aug 25, 2020 3:25 am
by Support
Welcome to the forum!
Yes, PrimoCache supports external SSDs as cache.
Please note that if you unplug the external SSD when Windows is running, SSD cache content will get cleared.

Re: Can I use an external SSD as cache?

Posted: Tue Aug 25, 2020 5:22 am
by HotLasagna
Thank you for your response!

What does "SSD cache content will get cleared" mean?

If I unplug the SSD while Windows is running and later plug it back in, will all the cache have to be re-built, or will the previously-cached files remain cached?

If all files are cleared from the cache, can I prevent this by using a 'safely extract' method of sorts?

Thanks!

Re: Can I use an external SSD as cache?

Posted: Tue Aug 25, 2020 5:35 am
by Support
HotLasagna wrote: Tue Aug 25, 2020 5:22 am If I unplug the SSD while Windows is running and later plug it back in, will all the cache have to be re-built, or will the previously-cached files remain cached?
PrimoCache will clear all the L2 cache content.

Re: Can I use an external SSD as cache?

Posted: Tue Aug 25, 2020 5:36 am
by Support
HotLasagna wrote: Tue Aug 25, 2020 5:22 am If all files are cleared from the cache, can I prevent this by using a 'safely extract' method of sorts?
no.

Re: Can I use an external SSD as cache?

Posted: Tue Aug 25, 2020 9:25 pm
by HotLasagna
Thank you again for your responses!

Here's another question. What happens if I remove the cache drive while the computer is OFF, turn ON my computer and use it without the cache drive, and later connect the drive again with the computer OFF? Will the L2 cache be intact, or will it be cleared when I turn the computer ON?

Thanks!

Re: Can I use an external SSD as cache?

Posted: Wed Aug 26, 2020 3:35 am
by Support
HotLasagna wrote: Tue Aug 25, 2020 9:25 pm What happens if I remove the cache drive while the computer is OFF, turn ON my computer and use it without the cache drive, and later connect the drive again with the computer OFF?
L2 cache content will be cleared in v3.x versions. However, if you remove the cache drive while the computer is OFF, turn ON your computer and then connect the L2 drive (the computer hasn't been OFF), the L2 cache will remain and will automatically update outdated cache content if source data have been modified.

Re: Can I use an external SSD as cache?

Posted: Wed Aug 26, 2020 3:56 am
by HotLasagna
That is great to know! I wish that cache wasn't cleared when removing the drive if the computer is ON, but turning OFF the computer to remove it is an acceptable comproimise I think. Still, removing a drive without clearing cache would be a good feature, I might hold off from making a purchase before that happens but who knows.

Thanks for the help, cheers.

Re: Can I use an external SSD as cache?

Posted: Wed Aug 26, 2020 8:12 pm
by Jaga
If Primocache can't track which blocks in it's cache have been altered because the machine was running when the cache wasn't mounted, it has to assume the cache is now "dirty" and it has to start from scratch. I think 4.x alleviates this problem by doing integrity checks against cache content, though I don't have it installed in my production environment to evaluate/test yet.

Re: Can I use an external SSD as cache?

Posted: Wed Aug 26, 2020 9:09 pm
by HotLasagna
Is 4.X currently available for purchase to standard users? I tried looking for it but the newest download in the main page seems to be 3.2.