SSD Optimizer as cache

[Mesonto]

Is it possible to use the SSD Optimizer as a cache?

In other words, not have it be just another drive in the DrivePool but have it as soon as possible pass its storage on to my HDD array? If not is there a way to get it to do that with the numerous Drive Balancer settings.

Or do I have to buy a 3rd party software like "PrimoCache"... which I don't even know would work or not?

[gtaus]

The SSD Optimizer is a plugin for DrivePool. When you add a SSD to your DrivePool pool of drives, you can designate it as a SSD (not HDD) for purposes of using it as a write cache for your DrivePool. You can tell DrivePool to flush the SSD cache as soon as possible, and it will write the data to your HDDs on DrivePool immediately. Some people like that system.

I found that I preferred to have my DrivePool SSD Optimizer set to store 100GB of data on the SDD before it would trigger a flush. That way, I can use my SSD as a 100GB read and write cache for temp and working files. That really speeds up my system. But the SSD cache only works for my DrivePool J: (on my system).

If you want a SSD cache for your entire system, not just DrivePool, then you would need a program like Primo Cache. They have a free trial period for you to try out the software to see if you want to keep it, or not. So, depending on what you want, you could try out the SSD Optimizer in DrivePool for just DrivePool files or install the trial version of Primo Cache for your entire computer setup. Primo Cache is good software, but I found that using the SSD Optimizer in DrivePool set to 100GB cache works well for me.

[Mesonto]

1 hour ago, gtaus said:

You can tell DrivePool to flush the SSD cache as soon as possible, and it will write the data to your HDDs on DrivePool immediately.

GTAUS,

This is my question then -- what would be the settings to do that? On the settings page I could check "Balance Immediately" but then it would also include all my other HDD drives to be balanced, and I do not need to do that. I just need to move my information from the SSD (cache style). But it would be a detriment to constantly spin my HDDs in the drivepool just to balance off immediately which I only need done once a month or so because I do not mind my HDDs being out of perfect percentage equalization.

i.e.:

1. immediately flush SSD cache upon copying
2. but allow HDD's to be within 10% of balance all the time
   (so HDD's aren't constantly running to balance)

1&2 I cannot figure out how to do together.

Regards,
James

 

[gtaus]

I can tell you that I have my Balancing "Settings" tab checked on "Balance immediately"; "Automatic balancing - Triggers" set to "balance ratio falls below 90%"; and checked the box "Or if at least this much data needs to be moved: 100 GB" 

From an older thread on this forum, it was suggested to set the box "Or if at least this much data needs to be moved:" at 1GB, which would trigger the cache flush almost immediately. One of the moderators, @Shane suggested this should be set to an amount that works for each person. He has more in depth knowledge of DrivePool, and maybe he will offer some advice.

As for me, I first tried a 1GB data to be moved trigger but found that my DrivePool was constantly re-balancing/flush the cache in the background. So I reset that amount to 100GB data to be moved as the trigger and now DrivePool does not need to re-balance/flush the cache very often.

Also, it appears to me, even though DrivePool "Balance immediately" is triggered by the data amount you set for your SSD cache, that does not necessarily mean that all your HDDs are going to be constantly re-balanced. I think what happens is that once your HDDs are balanced, then the SSD Optimizer will flush the SSD cache and write out the data keeping those HDDs pretty much in balance. I am only suggesting that because the first time I balanced all my HDDs, it took a long time. Now, when I see a SSD cache trigger a "Balance immediately" flush event, it writes the data from the SSD cache to the HDDs and pretty much is over. I don't think it triggers a full, all HDDs, re-balance every time because it is probably not needed unless your HDDs fall below your balance ratio you set (90% in my case).

2 hours ago, Mesonto said:

But it would be a detriment to constantly spin my HDDs in the drivepool just to balance off immediately which I only need done once a month or so because I do not mind my HDDs being out of perfect percentage equalization.

Well, I agree. But I don't think flushing the SSD cache would necessarily trigger all the HDDs in DrivePool to re-balance. I don't see that happening on my DrivePool. DrivePool appears to flush the SSD cache and then stops, which indicates to me that the HDDs did not need any further re-balancing. Having said that, even when DrivePool is re-balancing in the background, I can't see any slow down on my system. For some reason, re-balancing (even a full all HDDs re-balance) appears to be a very low priority background event and it has never caused me any problems or slow downs. 

BTW, you don't need a SSD to use the SSD Optimizer. In DrivePool, you can designate a normal HDD as a SSD drive. I considered just using maybe a fast 5TB HDD as my "SSD" designated drive and set the trigger data amount to 4.8TB. In that case, depending on how much data you write to DrivePool, a person might be able to go for weeks and weeks before any re-balance is triggered.