Help setting up volume specifics and Memory

FAQ, getting help, user experience about PrimoCache
Post Reply
xielvas
Posts: 12
Joined: Sun May 17, 2020 7:34 pm

Help setting up volume specifics and Memory

Post by xielvas »

I have 32 gb of physical memory, the primary purpose of the workstation is gaming and video editing.
I have 1 tb 970 evo plus which is my boot drive and program files drive
I have 1 sandisk 250gb extreme ssd which is used ONLY for game installs
I have 1 ocz-vertex2 50gb being used entirely to level-2 cache the raid0 disk pairs (640gbx2) and
4 tb disk seperated into two physical partitions of 1.8gb each.
I have prefetch set to ONLY games and Windows partition. I have level 2 set to the raid0 disk and the 4tb disk.
I have defer-write set to only the SSD drives (3) and the time is 3600 seconds (to limit writes to the drive).

My questions;

1. Which drives do any of you recommend I use level 1 on?
2. Are the settings above ok?
3. How much memory should I enable for the ram cache level 1 and what block size?
Currenly I have 8gb set and the memory overhead is 7.23gb using 4k block size.
4. Should I increase the block size and how much of a impact will I see doing this?

User avatar
support
Posts: 2712
Joined: Sun Dec 21, 2008 2:42 am

Re: Help setting up volume specifics and Memory

Post by support »

You may increase block size to reduce memory overhead. 7.23GB overhead is a waste of memory.

A latency of 3600 seconds might be too big in your case because L1 cache space is not very big. When L1 cache is full of deferred write-data, PrimoCache has to start the "urgent" writing process to free some space for caching new incoming write-data. If you see "urgent" writes, the performance might be not good. Besides, too big latency increases the risk of data loss on sudden power loss or system crash/freeze.

50GB level-2 cache seems quite small compared with more than 5TB target volumes.
Primo Ramdisk | PrimoCache
Romex Software Support

xielvas
Posts: 12
Joined: Sun May 17, 2020 7:34 pm

Re: Help setting up volume specifics and Memory

Post by xielvas »

So what exactly is the ratio size for level 2 cache? I am not going to use a 1tb ssd to cache out my hdd.
Also you never mentioned if I should have ram cache on all disks or just the spindles. I did adjust the block size to 8k and the overhead is 3.7gb now.

User avatar
support
Posts: 2712
Joined: Sun Dec 21, 2008 2:42 am

Re: Help setting up volume specifics and Memory

Post by support »

Could you upload a screenshot of the PrimoCache main dialog which shows your current cache configuration and statistics by highlighting the target volume, for our reference? Thanks.
Primo Ramdisk | PrimoCache
Romex Software Support

User avatar
support
Posts: 2712
Joined: Sun Dec 21, 2008 2:42 am

Re: Help setting up volume specifics and Memory

Post by support »

xielvas wrote:
Mon May 18, 2020 1:56 pm
So what exactly is the ratio size for level 2 cache?
It depends on how much data in source disks is often requested. Generally speaking, bigger cache space, better cache performance. As you might have known, the cache works by storing the data that were read and providing them on next read requests. If the amount of hot-data is big while the cache space is small, old saved cache contents might be replaced very often, causing bad cache effects and efficiency. Of course, if your hot-data is not much, you may not need to use big cache space otherwise it might be a waste of your investment.
support wrote:
Tue May 19, 2020 2:59 am
you never mentioned if I should have ram cache on all disks or just the spindles.
Actually it's up to you. If you prefer Defer-Write on all disks to improve their write performance, then you may have L1 cache for all disks. Please note that Defer-Write might cause data loss on sudden power loss, system crash/freeze, so it is recommended that you may only enable Defer-Write on volumes where temporary, unimportant or reproducible data is to be stored.
xielvas wrote:
Mon May 18, 2020 1:56 pm
I did adjust the block size to 8k and the overhead is 3.7gb now.
I think the overhead is still too big, you may increase block size to 32KB or 64KB.
Primo Ramdisk | PrimoCache
Romex Software Support

xielvas
Posts: 12
Joined: Sun May 17, 2020 7:34 pm

Re: Help setting up volume specifics and Memory

Post by xielvas »

Here are the screen shots requested.
I only wanted delayed write on the SSD to limit the frequency of writes to them. I have level 2 on the mechanical drives. Level 1 is on all of the drives and windows read/write cache is disabled on on drives.
https://www.dropbox.com/s/ajev7tc1u7w1b ... 8.png?dl=0
https://www.dropbox.com/s/ajev7tc1u7w1b ... 8.png?dl=0
https://www.dropbox.com/s/ajev7tc1u7w1b ... 8.png?dl=0

User avatar
support
Posts: 2712
Joined: Sun Dec 21, 2008 2:42 am

Re: Help setting up volume specifics and Memory

Post by support »

These 3 screenshots are same. I'd like to see your PrimoCache main dialog which shows the cache configuration and statistics.
Primo Ramdisk | PrimoCache
Romex Software Support

User avatar
Jaga
Posts: 484
Joined: Sat Jan 25, 2014 1:11 am

Re: Help setting up volume specifics and Memory

Post by Jaga »

xielvas wrote:
Mon May 18, 2020 1:56 pm
So what exactly is the ratio size for level 2 cache? I am not going to use a 1tb ssd to cache out my hdd.
As a rule of thumb, I try to get between 10% and 25% "data coverage" on the cache. i.e. if your data on the volume was ~4TB in size, you'd want a minimum L2 cache of 400GB, or as much as 1TB. Part of that also depends on how often the data is accessed - if you have media you rarely playback, it should be subtracted from the total data being cached.

I personally also use a block size of 16KB, since I feel it is small enough to retain good speed gains, while also dropping overhead. However if you end up caching very large target drives you may end up needing to raise RAM a bit to compensate, OR simply raise block size to 32 or 64KB as Support suggests. There's always a hit to RAM when indexing a cache, and larger caches have more of an impact.

Post Reply