drobo mini performance issue

I had looking for a portable high capacity storage system for a while and turns out there are two popular in the market. Drobo Mini, and the Pegasus J4 from Promise. I finally grab this drobo mini because of the recent price drop from 660US to 320US… very attractive price!

Very Slow Overall!

At the first time, I reuse my existing 2 x 5400rpm Toshiba 1TB harddisk and 2 x WD 5400rpm 500GB harddisk, I inserted them and format it as 8TB target size. Open the blackmagicdesign disk testing tool, the result is ~120MB write / ~60MB read? that is very slow! Then I read the recommendation from drobo website to add a msata SSD for acceleration, so I added a 128GB crucial m4 SSD. Re-run the test without any improvement.

Getting better in write performance

Later, I bought two latest Hitachi 7200RPM 1TB harddisk to replace the 500GB WD harddisk, by swapping the disk one by one and wait the rebuild complete, I rerun the test, the result shown ~160MB write / ~75MB read. It still darn slow! why?

Trying to figure out the root cause

I’d decide to give it a last try to replace the left by 5400rpm harddisk to the same Hitachi 7200rpm 1TB harddisk, same by swapping one by one and let it rebuild. rerun the test, the result shown ~220MB write / ~90MB read. Still very very slow, even slower the single drive.

Reset works!!

When i was really disappointed with no cure to manage it,  I press the reset button in the drobo dashboard, reformating it and rerun the test. Oops!? the result pop up ~210MB write/~260MB read! that is what I’m expecting.

Slow performance come back

When i was so exciting and transferred all file (~1TB)  back to the drobo, I rerun the disk test to ensure the drobo is in good shape, however the turn me down again. The read performance drop dramatically again, but not worst as ~90MB read, it still had ~160MB to ~200MB read inconsistently. So I’m going to find out why again. That is troublesome, and no answer in google.

Format SIZE is somehow do the trick!

I start to drill into the disk size may affect the performance, I format the drobo as 4 TB , 8TB and 16TB for testing, each time I record the performance after a fresh format and after copy those 1TB data (~200k files). The result as below

Fresh formatted  (4 x 1TB RAW)

Formatted Size Write (MB/s) Read (MB/s)
4TB 231 302
8TB 213 265
16TB 209 221

After 1TB data (~200k files)

Formatted Size Write (MB/s) Read (MB/s)
4TB 192 251
8TB 170 208
16TB 143 197

As the above result, you see the more close to raw size the more speed.


SSD accelerator size in comparison

Many people asking how the accelerator bay SSD size affects the drobo performance, I’d borrowed another 64GB and 256GB Plextor M5 SSD for the comparison, and I’m telling you solidly, there are NO different I can tell in backmagic disk test tool, AJA nor Xbench, don’t spent too much money on this SSD, just 64GB will be fine.



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