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PrimoCache with SSD's instead of HDD's

Posted: Fri Oct 02, 2020 8:50 pm
by con
So I am using the server editions of PrimoCache and I have only got SSD's but the speed performance gains are incredible even but i am curious are there any downsides and the blocksize setting how do i know what is the best blocksize to choose....

Performance before Primocache installed and After PrimoCache was installed.
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The Drive setup on my servers is i have 3 SSD's.

2 of the SSD's are C:/ Drive mirroring eachother for data protection incase hard drive failure swap it and put a new one in "mirrored"

The 1 spare SSD the 3rd i decided to use it as a Level 2 storage.

Re: PrimoCache with SSD's instead of HDD's

Posted: Sat Oct 03, 2020 7:09 am
by Jaga
The speed gains you are seeing are likely due to the L1 cache in the Cache Task you created. When you start to see the L2 used, you'll lose speed since you are "caching a SSD with another SSD", which doesn't help and only adds overhead. Remove the L2 SSD that is caching the target SSDs (unless it is MUCH faster than they are).

Re: PrimoCache with SSD's instead of HDD's

Posted: Mon Oct 05, 2020 10:19 pm
by con
You say overhead how is this bad how will it slow it down ? Would increasing block size to 512 not solve that or perhaps an autmatic overhead feature ?

Re: PrimoCache with SSD's instead of HDD's

Posted: Tue Oct 06, 2020 4:18 am
by Jaga
Overhead, as in "making a single step process into a two step process, without increasing the speed of the devices for any step". It's like having the postman deliver your mail to another office locally, where yet another postman picks it up and delivers it instead of just having the first one do so. You are adding unnecessary delay to the routing without any additional benefit.

If your L2 was hosted on a fast NVMe that would change things, since it outperforms your regular SSD (the target volume). It would in essence turn one of the postmen into a formula one race car driver, ensuring your mail is delivered faster than normal.