I have a Drobo S currently attached via FW800 to my MacBook Pro (Unibody). When transferring data between a LaCie Rugged 500GB disk and the internal hdd of the MBP (a 500GB WD blue) i get around 50MB/s.
With Drobo S it is a measly 42MB/s with peak up to 43.5. This is as you might imagine a bit frustrating since i hoped for the increased speed promised by Drobo S over Drobo FW800.
In my Drobo S i currently have three drives: one Samsung 1TB F1 and two Seagate Barracuda LP 2TB.
Drobo is not a RAID 0.
It is thus perfectly normal that it is not faster than an external FW800 or USB2 disk.
Furthermore, parity calculation and control will make it slower than the slowest disk in your Drobo-S.
Sorry to disappoint you, but the 42MB/s you get out of your Drobo-S could be considered as an excellent figure by previous Drobo (non S) users…
That is not quite true. The data you are writing out is spread over multiple hard disks. When you write out data it probably waits for the slowest drive to finish, but you are only writing a fraction of the data to that particular drive. Also when using drives of different sizes the slowest drive is also the smallest and so will be used the least.
Unfortunately, the disk access time has 3 components, and the 2 biggest ones are independent of the data transfer length :
seek time (the arm moves to the proper cylinder)
latency time (1/2 rotation)
transfer time (the bytes transfer)
Smaller blocks to read or write mean less transfer time, but typically it is less than 30% of total. Sequential long blocks transfers DO increase disk and Drobo transfer rate, but the spread on multiple disks and length reduction is not enough to decrease the degradation due to spreading (non-synchronized disks => longer latency) and software parity computation.
And disk buffers are flushed by long sequential transfers, so their acceleration is minimal in that case.
the one thing that would be ideally sped up on mine would be the access time for itunes, 3-5 seconds waiting to play a track is looking like my drobo s will be on ebay soon.
for everything else its fine but my 3.5tb music library, the only reason i bought the drobo, its not really very good at all.
if datarobotics can speed this up ill be happy cos for everything else its fine, fast, no probs, just wished my music wouldnt sit for a few seconds to think about playing the track . . . . .
ohh all my drives are 7200, gigabit ethernet using a 3com 24port managed switch, rackmount jobbie no expense spared it was perfect before i moved it all to the drobo (was on internal drives in my sept 09 8 core 16gb mac pro)
Just setup my Drobo S with eSATA and I’m getting between 45-80 MB/s.
I’m copying from a local SATA drive to the Drobo S which I have 5 drives (2TB, and 4 500GB) which all are at 7200RPMs. I’m just using rsync --progress to get my results. But doing large ISO disk images I average 70MB/s or so. Doing other types of files I’ve seen it go from 45-80. But anything that takes more than a couple seconds seem to go around 70MBs.
I’m using ext3 with a 8TB LUN. I’m trying to fill up past 2TB to see if I get any of those slow down type problems or if I have any problems deleting. But right now things are about as fast as my local SATA drives for copying and moving things.
I did a speed test on Linux that shows pretty good results. Here you go:
File size = megabytes
Blk Size = bytes
Rate = megabytes per second
CPU% = percentage of CPU used during the test
Latency = milliseconds
Lat% = percent of requests that took longer than X seconds
CPU Eff = Rate divided by CPU% - throughput per cpu load
Becarefu using dd. The blocksize, bs=512k, has a HUGE impact on results. On my DroboPro, I “dd-ed” a file to /dev/null with bs=512k, it copied at 70.8MB/sec. Setting bs=1024k resulted in 90.9MB/sec, i.e. 30% faster.