Cache vs unassigned drive


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I ordered a 6TB drive today to add to my server. I was planning to use it as an unassigned drive to store some backups and Storj data (because the last one constantly spins up my drive and parity drives)

But an hour ago I started thinking, maybe it's better to add the 6TB HD to a new cache pool. If I select my Storj to prefer cache, it will never be moved to the array.

It seems better this way, no plugins needed, everything in the array. What do you guys think?

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I think most people select an SSD to operate as the Cache for various reasons.  May want to consider that.  Cache drive allows for faster operations of your important files and transfers, etc.  

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43 minutes ago, Squid said:

Using cache pools for permanently attached devices is what you should be doing.

So if I understand correctly, if I plan to leave the drive permanently connected you would choose a cache pool. Even if I am not planning to use it as a real cache, just storage that does not need parity protection or speed.

 

I have a ssd cache pool in use but with the new cache pool feature I started thinking to use a second cache pool instead of the unassigned drives plugin.

 

Sorry if my explanation is not clear. I am not a native English speaker.

 

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3 minutes ago, Croontje said:

So if I understand correctly, if I plan to leave the drive permanently connected you would choose a cache pool. Even if I am not planning to use it as a real cache, just storage that does not need parity protection or speed.

 

I have a ssd cache pool in use but with the new cache pool feature I started thinking to use a second cache pool instead of the unassigned drives plugin.

Yes, this is correct.  For permanently attached storage, cache pools are easier to deal with than Unassigned Devices and provide more flexibility.  UD still has several good uses especially with USB and other storage that is not always connected to the server.

 

If you are looking for speed, of course SSDs are better than HDDs as cache devices.  A cache "pool" can be a single device or multiple devices.

 

You can assign your HDD as a cache device and designate share(s) as cache only or cache prefer using this HDD cache "pool."  The only difference is what happens when the cache drive is full.  Prefer causes data to spill over to the array; cache only does not.

 

Nothing on this cache drive would be parity protected and therefore would write to the HDD at the speed of the drive.

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