R720 Internal SD Cards as Cache Pool?

[dskaggs]

Question for anyone who has a Dell R720 as their unRAID server: can you use the internal dual SD card module as a cache pool? I have a new (to me) R720 that I am going to be configuring unRAID on and thought I might grab a couple of 256GB SD cards and use that as the cache drive pool to save a 3.5" drive slot on the front. Thought I'd ask here if anyone has done that before I spend the time and money buying the SD cards and the module.

 

Thanks in advance!

Dan

[Frank1940]

I am expressing an opinion here:  While SSD and SD cards use similar technologies, their implementation parameters are considerably different.  SSD's are designed to be a read/write device where the number of reads and writes are close to being equal.  SD cards are intended to be more of read-only device or a long term storage device.  Thus, SD cards controllers are not near as diligent at write-leveling distribution of data as their SSD's cousins.  Which means that SD cards have a significant shorter life under the same usage pattern. 

 

With regard to the cost issue, you could find that over the life of the average SSD drive, you could easily be spending more on replacement SD cards that fail.  You should realize that there is a reason why SSD's cost more per GB than SD cards.  If the cards were equivalent in all respects, you would not be the first person to be trying this...

[Frank1940]

I also wonder if there is a spot inside of the R720 case where you could Velcro an SSD.  They have no mechanical vibration and their small size often makes it possible to find an area to do this.  

Edited December 25, 2019 by Frank1940

[mrbilky]

I'll only add that you can install an ssd drive bay adapter to your optical drive bay for additional space but that does not help with a pool although check to see if you have a unoccupied sata port on your motherboard as my R710 has one your manual indicates you should have one as well then all you need is to tap a power connector with a couple wago clips and you will have 2 new options for a cache pool not sure what version of sata the R720 has but mine are sata 2 so that may be a deal breaker for you not sure of your use case

[dskaggs]

Thank you both for the info. I had suspected as much based on not finding any information on people doing that in my research.

@Frank1940 There's plenty of room to put an SSD in there (or maybe 2). I'll probably wind up reusing the DVD SATA and power connector and see if I can find the correct cable to hook up to the "tape backup unit" SATA and power connector for the 2nd one. I just need to do some research and see which SATA spec the onboard connections use.

 

Cheers to you both.

Dan