So I primarily use my uNRAID Server for streaming movies to local clients throughout the house....I also share them via plex with some friends.

 

What would suit me better for a cache drive? A 128GB SSD or a 1TB Lacie External HDD?

 

The most I transfer to the server on a daily basis is usually under 10GB if that makes a difference.

 

My main reason for wanting a Cache drive is to run Plex, SAB, Sickbeard, etc.. and allowing my disks in the array to spin down.

You cannot use an external drive as a cache.  Unless you mean you will crack open that Lacie and use its guts as an internally connected SATA drive.

 

Beyond that there are two questions you need to ask yourself

 

1) Do you mind if the drive storing my Plex library is "spinning" 24/7

2) If you use an SSD for a cache drive, will it be big enough to handle your full Plex library and all the writes I will make to it before the next scheduled MOVER script run? 

 

For reference my answer to both questions was "no" so I decided I wanted my plex library on an SSD, and that SSD could not be my cache drive.  Result is I have an SSD mounted outside the array. 

 

Since you say you xfer no more than about 10G per day then you need to look at the size of your library.  If you generate Plex index files they can really start to take up a lot of space.  If not, by all means start out with your SSD as a cache.  If you start to outgrow it you can always mount it external to the array and replace the cache with a spinner to take care of array writes.

 

Your final consideration is trim support of your SSD.  As a cache drive formatted as ReiserFS you will not have trim support.  However if it has good garbage collection, and/or you run fstrim nightly as a chron job, then you'll be fine.  Mounted externally and formatted as ext4 you can enable trim support.  http://lime-technology.com/forum/index.php?topic=30496.0

You cannot use an external drive as a cache.  Unless you mean you will crack open that Lacie and use its guts as an internally connected SATA drive.

Actually if the external drive is connected eSATA it will work as a cache drive I had my N40L setup with external cache to eSATA for quite a while.  My N54L currently has a two drive external eSATA port multiplier setup with cache and parity drive works well.

True.  I just assumed that lacie was a usb drive and not esata.

True.  I just assumed that lacie was a usb drive and not esata.

Probably is.  Not many that are both that aren't home built.  Just wanted to point out that it can be done with the correct interface.