I apologize in advance if this is a dumb question, but I am not a technical expert and have searched these forums looking for my answer without much success.  I am looking to add a few more drives to my unraid server.  I was going to add a two more 1 TB drives for now.  Now most drives have either a 16mb or 32mb cache and the 16mb are typically cheaper.  Does this effect performance of the unraid server?  If so, then how?  I have no problem just spending the few extra dollars for the 32mb drives if it is worth it.  The two drives I currently have in my server are 16mb, so if I was to get 32mb drives to mix with my 16 mb drives which would be best suited for the parity drive?  I would appreciate any help on the matter.

 

Thanks in advance.

Cache is a kind of fast memory that stores a chunk of (in this case) hard disk data.  Every new read causes the oldest data in the cache to be overwritten with the newest data read from the drive.  If a piece of data is located in the cache, the drive can return that data very fast.  The larger the cache the more data can be stored at once.  For certain types of solutions, larger cache can make a huge performance difference.  But for media playback, it normally is not a big issue.

 

But typically 32M cache versions of drives come out AFTER the 16M cache drive versions.  Some of the 32M cache versions have higher density platters or other new features that can make a speed or reliability difference.  It takes a little research to find if, for a particular model, there are these types of differences.  In general if I can get the 16M cache version at a much better pricepoint than the 32M versions, I'd go with them.  But for a $5 - $10 premium, I'd go with the 32M versions.

 

Hope this helps.

But typically 32M cache versions of drives come out AFTER the 16M cache drive versions.  Some of the 32M cache versions have higher density platters or other new features that can make a speed or reliability difference.  It takes a little research to find if, for a particular model, there are these types of differences.  In general if I can get the 16M cache version at a much better pricepoint than the 32M versions, I'd go with them.  But for a $5 - $10 premium, I'd go with the 32M versions.

 

I have read that the 1.5TB seagate drives with the 32MB cache benchmark in the WD 10,000 rpm Velociraptor range.

 

I can attest that switching from the 1TB WD 16MB cache to the 1.5TB seagate 7200 RPM/32MB cache increased my system's write performance a good deal.

 

For the data drives, I switched my rtorrent drive from a WD 1TB 5400RPM 16MB cache to a Seagate 1TB 7200 RPM 32MB cache drive and also so a performance boost.

 

I think spindile speed and cache both had a good deal to do with this.

 

For my movie drives, I kept the WD 1TB 5400RPM 16MB cache drives as they are usually read/written sequentially and would not show as much of a perofmrance boost over my other drive which is read/written randomly all day long.

 

 

At the very least choose the largest fastest drive you can afford for the parity drive.

If you can movie all of your smaller randomly accessed files to one drive (documents, pictures, downloads, etc, etc) I would use a faster larger cache for this.