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DrivePool SSD Cache


dsp

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Is there a way to make Drivepool store the most recent x GBs of files on a certain disk, and then move old files off of it and balance into my archive disks? 

I would like it so my most recently added files are stored on my SSD drive but slowly push out all data to my archive disks. Currently the SSD Cache plugin will let my SSD fill up, but then immediately empty it out once it starts to balance it. 

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I'm also interested in a basic SSD cache drive.

Ideally, I'd like the SSD to act as a write cache, and then move data to the storage drives to be duplicated among the storage drives nearly immediately.

Also as a 'smart' read cache to learn commonly accessed files, and basically make it a temp storage of files, having nothing to do with duplication and balancing of the actual hard drive storage.

So the SSD should not be seen as part of the pool at all, but simply, a smart cache so you can have fast access reading and writing data and let all the duplication and balancing happen independent of the SSD.

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No.  I asked about this a few months ago as well.

At the time, I started working on a PowerShell script that would move stuff in FIFO fashion from SSD to platter.  At that time, I failed.  But I've started working on it again.

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15 minutes ago, fly said:

No.  I asked about this a few months ago as well.

At the time, I started working on a PowerShell script that would move stuff in FIFO fashion from SSD to platter.  At that time, I failed.  But I've started working on it again.

Ah darn. After I posted this, I started to research alternatives and came across primocache. If you heard of it or used it before? I am wondering if primocache might be a useful alternative. 

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Hi Chris  and others - I'm pretty confused about the SSD optimizer and how plugins work together.

I've read in some older threads that if you use the SSD optimizer you should disable other balancers - but that means losing a lot of important functionality, which is not at all redundant with SSD optimizer.

I thought the point of the SSD plugin was that files would initially go to the SSD, and then from there, would gradually be moved to other disks, duplicated on the archive disks and balanced according to rules.

It doesn't make sense to me that these would be in conflict with the SSD optimizer .  This would imply you must choose between faster writing to the pool or having files end up where you want. 

Also - I read that you need to have as many SSDs as you your max duplication - is that right?  Again - this doesn't seem to make sense if the SSD is a temporary location.  If I turn off real time duplication, do I still need multiple SSDs?  

If SSD optimizer is highest prioirty - shouldn't off loading to archives happen before all the other balancers?  It seems to me that this plugin should be designed to not worry about duplication since that would reasonably be for long-term storage.  Or at least there should be an option to say - "don't worry about duplication until you get stuff onto the archive (non-SSD) disks."

 

Also - someone had said that using multiple balancers result  in them "fighting with each other". Again - this seems to contradict the prioritization.  If two balancers would result in different arrangements - shouldn't the one with higher priority win in situations where they conflict? 

So - for instance - if Drive Usage is first - and it says put unduplicated files on drives 1 and 2 and 3 but not 4, and the next balancer is equalize distribution across disks based on unduplicated files percentage, my assumption is that DP will balance unduplicated files across disks 1,2 and 3 but NOT 4 since the higher priority plugin says don't put them there at all.  However, one poster implied that after doing the first balancing, DP would then re-balance according to the next balancer - even if it conflicts with the previous.  If so - it isn't really prioritization - it's just sequencing.  If that's really the case, then one really should only use one balancer, which again, makes them much less useful.  I'm hoping what I read was incorrect.

Is this not the way it works?  If it isn't, we need some better documentation on how these interact.  I have assumed that I can use as many plugins as I'd like, with the understanding that prioritization position determines which have the most "say" over arrangement. 

 

 

I

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