Drobo

Drobo Transfer Lag

I was curious if anyone else has been getting this same kind of transfer lag. I know that the drobo is “slow” compared to other FW800 devices but ~30 mg/s constant transfers. I popped two Western Digital Greens 1TB’s into my drobo V2 and started transfering data over. This is the transfer pattern that I got.

The transfer data number would pause every few seconds and then start up again.

On a side note, I did pick up two 64mg cache “advanced” 4k drives for my system but I newest firmware said that it was supposed to support these drives. shrug

My Drobo pauses every now and again. But to reduce variables, if you can establish a reasonable sized RAM disk and transfer to/from there, you will be able to eliminate competition on the peripheral bus as a cause.

I understanding pausing for a system that can’t keep up, but I’m running a late 2009 Macbook Pro with a 2.8 C2D, 4 gigs of memory and 7200 RPM 500gb HDD. I honestly don’t think it’s my system that’s causing the issue. As for the peripheral bus, drobo’s the only thing connected. It really should be able to easily handle a sub 40mg/s transfer.

30MB/sec is in the reasonable range for a drobo. i suspect the pauses are because drobo has cache - so its filling the cache quickly, then drobo is doing its parity thing and writing it to the drive, then repeating the cycle over and over

[quote=“Syan48306, post:3, topic:1083”]I honestly don’t think it’s my system that’s causing the issue. As for the peripheral bus, drobo’s the only thing connected. It really should be able to easily handle a sub 40mg/s transfer.
[/quote]

It’s not so much the system being too slow, it’s a matter of the bus being overloaded - bus bursting can happen regardless of the speed of the machine, and even if you have only one peripheral connected.

At the core, there are a limited number of “roads” for data to take on the bus. So, if your internal storage controller is connected to the same bus that the interface your Drobo is on, if one does a large burst, it’ll “choke” the other one’s transfer.

I think Docchris is right that it’s likely due to a cache. But if you have the same problem on both ends (your internal storage and the Drobo), then you’ll see more pausing as you’re getting back-and-forth, kind of like half-duplex transmissions.

so…the million dollar question. Most likely what’s causing it and how do I fix it :3

I don’t have any internal problems, just reading AND writing to the drobo, I experience spikes. Just as a comparison, xbench claims that my average transfer is somewhere in the 6-7mg/s range due to all these spikes. Transfering a 1 gig file takes up to 4-5 mins to transfer over. Is more likely a problem with drobo or the HDD’s. I did a quick test and it didn’t do anything like this when it only had one hard drive in the system.

We don’t use xbench to do performance tests, does not give an accurate read on the Drobo.

We use AJA Kona.

I am testing write speed to my Drobo now. I have encountered an interesting fact: The Drobo is working internally to rearrange something HOURS after Factory Reset and format. During this time you will experience those dips in speed. I can’t figure out why, because dives are empty, but the fact remains.

Conclusion: Let the Drobo stay connected and active, but do not read or write to it, until it stops using the drives. Maybe this will take days in some configurations.