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Correct Settings for SSD Cache


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Hi, I just want to make sure I'm using my SSD as I want to.

I have it added to my DrivePool, but I only want it to be where new files land - then get moved to another disc.

 

I have the SSD Optimizer installed and at the top of the Balancers list - I have my SSD selected as such, and all my other drives as Archive.

This is where I'm not sure of the proper settings - next in my Balancers list is the Drive Usage Limiter - in these settings, do I check off both Duplicated and Unduplicated for the SSD drive? Or leave them both unchecked? I don't want files permanently stored here, so I want to uncheck them, but not sure if that's correct.

 

Then, in the File Placement tab, do I uncheck my SSD drive from all the folders so that nothing gets stored there? Or do I leave it checked for every folder?

 

Thanks!

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The list of the balancers is also the priority of them. 

 

If the SSD Optimizer is at the top, then it gets first priority.

 

That said, the Drive Usage Limiter controls what *can* be placed on the drives.  If you uncheck "duplicated" then it would means that it would actively avoid placing duplicated data on the drive. 

 

But basically, you should be fine leaving the other balancers enabled. 

 

 

 

But if you're are using duplication, then you do need 2+ drives for SSD.

 

 

 

And if you're using file placement rules, you'd want to select the SSD drive too, or it won't use it, at all. 

(balancers respect file placement rules by default). 

 

That said, on the main settings page for the balancing, you will want to uncheck the "Unless a drive is being emptied" option. 

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So I did what you said and got the exact opposite of what I want...

The SSD filled up because I wasn't paying attention, but DrivePool is using the SSD as storage space now - not just for cache... you said:

 

"And if you're using file placement rules, you'd want to select the SSD drive too, or it won't use it, at all."

 

I asked what I had to select in the File Placement rules to just use the SSD as cache..  maybe I wasn't clear in my question... here's what I want:

 

1. the SSD to ONLY be used for cache for the pool

2. need to know what to select for the SSD in the a) drive usage balancer and B) in the file placement rules.

 

Currently, I have it selected for every folder in the file placement rules (as you said it wouldn't "be used" if it wasn't.. ) it's also selected in the drive usage limiter for duplicated and unduplicated files.

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But if you're are using duplication, then you do need 2+ drives for SSD.

 

Can you explain this one a bit more?  I'm planning on adding an SSD to my pool which is all duplicated data.  I don't want files to "hang out" on the SSD beyond just being used as a write cache.  I'd like to have them offloaded to the pool pretty much immediately so they're all duplicated.  Are you saying this is not possible based on the way the optimizer works?

 

I think this is the same goal as the OP.

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Yes, that is what I want too...

I was also confused by the comment you quoted.. needing 2+ SSDs for duplication.

 

I just want all new writes to the DrivePool to land on the SSD, but then not "hang out" there - they should then be written to whichever drive is necessary based on balancer rules, etc...

 

That's what I thought this functionality was for?  Maybe it's not.

 

Chris?

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For SSD Optimiser to work fully you need the same number of SSD's as you have duplication

 

You can have more than that hence the +

 

I have four for one pool and they work as pairs if you have real time duplication enabled - i.e. simplistically file 1 goes to pair 1 and file2 to pair2 then file3 to pair1 etc - with files duplicated in real time so the pairs fill up at the same rate etc

 

Once you have the SSD optimizer installed ( from experience turn off all the other plugins apart from scanner - otherwise you will get a lot of file shuffling on the pool as the plugins "fight" each other)

 

Set which disks are ssd's (you can set any disk for this although speed will suffer if its a HDD) 

 

Your settings should look something like this

 

 

 

Then set your balance settings to a short ish time like 3 hrs or balance immediately and the data copied to the pool(ssd's) will then get moved off to the archive disks.

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I'm not using duplication.

I just want the SSD to be where new files are written, then moved to the rest of the pool... for fast writes to the pool.

That's it. No duplication / fanciness.   :)

 

What about file placement rules? Allow files to be written to the SSD?

Last time I turned that on files started getting written to the SSD until it was almost full (went past the 25% full setting that I had set in the SSD Optimizer).

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I've done that.. but I've also been using other balancers. 

For example, I use the Disk Space Equalizer to add files to my disks based on percentage full of each disk, rather than a value in GB.

This balancer is lower in priority than the SSD optimizer, so I didn't think it should affect it... but maybe it does?

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Ok, but what if I want the functionality of another balancer as well? Which I do..

If this is not supported, then that's why I'm here asking questions.. to find that out.

There should be a better explanation other than, "well, those balancers, they like to fight, so, uhhhh, turn the other ones off..."

 

It's a good tip, and I thank you for that - I'm just looking for some actual technical details on how the program chooses to do what it does - so that I can get it to do what I want...

Which includes:

a. the SSD functionality that I've written about above, and

b. the Drive Space Equalizer - "Equalize by the percent used" option

 

Are these two options a possibility to work together? It seems that they should be able to.

If so, can anyone share with me the proper configuration?

 

Thanks.

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Chris will be along eventually

 

I played with various balancer when i first setup my pool

 

SSD Optimizer is a "special" advanced balancer plugin and when you have other plugins eg drive space equaliser they have different goals 

 

So simplistically the top plugin sets some rules - move x to y etc - then the next balancer sets up some other rules - move a to b - DP then runs through the list of data moves

 

so if x and y are similar data to a and b the data can get moved twice - and the next time DP balances a and b get moved back to x and y - and the merry go round begins again

 

Hence why i said turn off all other balancers - This need fixing so when SSD optimizer is added there is a warning/switch to turn off the other balancer plugins - it will come eventually once the cloud drive is released and we can get some changes and updates to DP and Scanner which are long over due

 

Chris recommends the same - i.e. turn off the other balancers when using SSD optimisers - try searching the forums 

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