Idea for consideration. It occurred to me like most storing multimedia content that there might be a real world usability gain to be had for free.

 

If you have a cache drive each night the data is moved away into the array. However if you are like most and are uploading movies and tv then statistically these new videos are the ones you will watch sooner.

 

As it stands if I add 10 tv episodes on Monday and watch them over the next week each time i do so I spin up array drives. Meanwhile my cache drive is sitting almost empty spun up doing cache drive things.

 

If we allowed the definition of a xx% reserved area on the cache drive, each night copied the new contents onto the array but allowed this reserved area to retain duplicates (on a last in first out basis) what we gain is the safety of the array but a perceived real world bump in performance for the content you are more likely to watch sooner.

 

Comments?

Normally unRAID only spins up the drive that you are reading from, so if streaming one file from the array, just one drive is running.  That's one of the benefits of unRAID over other RAID-type filing systems.  Depending on the spindown timeout settings, the chances are that your cache-drive is not spinning quite a lot of the time.  The other way to look at is is that if your read from an array drive but write other data to the cache, then the two drives can do their thing without any seeking between two areas of the disk (if both things were on one disk), which can only help performance.

I don't see this actually providing any perceived boost in performance.

Read performance on the cache or array is going to be the same for a movie.

The only perception is how long it takes to start the movie because drives may be spun down.

 

Perhaps setting an age in the mover so that only files over a certain age are moved to the array would provide the boost in startup.

yes sorry the boost in performance is primarily related to the spin status of a disk .

 

Changing the the mover script delay would be a much simpler solution but your paying the big price of increasing the probability of a single drive failure losing you data.

 

As a real world example I often seen a drive being spun up per episode as I watch them. Over a year that's alot of potential spin up saves when multiplied up by a family of people. Admittedly I am anal about drive spin ups I would like to keep them to an absolute minimum but surely that is a good thing in itself.?

Another choice which is something we do at work is to only execute the mover at filesystem full status of X%, then only move the oldest files.

 

Taking this further, the mover could be changed to rsync all files on the schedule, but only delete the oldest files until the space reaches less then X% (60%??).

 

There may be an issue as the userfilesystem may need to make a preference.

I.E. Check for a files existence on the cache drive first.  That way duplicates come from cache before array.

We would also have to deal with the log overload that would result of always having more than one copy of some files.

 

But none of this seems terribly insurmountable and it could be a nice transparent boost to any cache drive user.

It can be done with some fancy shell programming in the mover script.

Sorry to bump an older thread but I thought I'd put in my two cents.

 

My cache drive is mapped as it is ~150gb and on rare occasions I will fill it so by having it mapped I can keep an eye on the available space. I quite like the peace of mind of being able to physically "see" whether there is currently anything sitting on the cache drive, even just by glancing into "My Computer." This way I know if i have data that is currently not protected.

 

 

I definately understand the reason for wanting to "keep" a copy of recent data on your cache drive but this could cause confusion as to what data has been moved (protected) and what data is still vulnerable to a cache drive failure. Obviously though this feature could be made to be turned on/off in the options so users can choose whether they want to use it or not. The idea of recent data being duplicated on the cache drive is a brilliant idea for people who can see the benefits in this type of thing and I would definately consider using it myself however with my current habits I do like to be able to physically see whether there is data on my cache drive or not.

I have the mover run once a week and it works OK for keeping the new media when I want to access it. I set the important backup type shares to not use the cache.

Sorry to bump an older thread but I thought I'd put in my two cents.

 

My cache drive is mapped as it is ~150gb and on rare occasions I will fill it so by having it mapped I can keep an eye on the available space. I quite like the peace of mind of being able to physically "see" whether there is currently anything sitting on the cache drive, even just by glancing into "My Computer." This way I know if i have data that is currently not protected.

 

 

I definately understand the reason for wanting to "keep" a copy of recent data on your cache drive but this could cause confusion as to what data has been moved (protected) and what data is still vulnerable to a cache drive failure. Obviously though this feature could be made to be turned on/off in the options so users can choose whether they want to use it or not. The idea of recent data being duplicated on the cache drive is a brilliant idea for people who can see the benefits in this type of thing and I would definately consider using it myself however with my current habits I do like to be able to physically see whether there is data on my cache drive or not.

 

I like the idea of mapping the cache drive. Several time I have found stuff sitting there that had not been moved due to the drives hitting there min free space setting.

 

Probably also my fault for not setting up some some form of notifications to be sent from unraid.

Here is a big flaw in this idea..

 

If you are watching your new movies/tv shows off the "cache drive" and start pushing lots of  new data to your server, it is going to write to the cache drive (since you have it set that way).

It will slow down your writing speed considerably and probably lag out your video stream.

(an SSD wont be effected by this, but it is probably to small for this use at this point)

 

Also all the data on the cache drive is unprotected...

 

this is point of a cache drive is to prevent this from happening.

 

 

My 2 Cents...