Extremely slow read speed from OS X

I’m using a Drobo FS with a new iMac (OS X 10.6.4), and, while its write speed seems adequate (around 20-25 mb/s), its read speed (less than 1 mb/s !!) makes it pretty much unusable from OS X.

Strangely, I’m getting 15 mb/s reads (which still seems inadequate, but it’s certainly better than 1 mb/s!) on my Win7 PC. So I’m assuming this is an OS X issue. Oh, and I should mention that I’ve got dual disk redundancy enabled, and one share configured for Time Machine.

Any suggestions?

Do you get the same speeds when directly connected to the NIC card on your Mac?

Wow! I’m getting around 35-40 mb/s (read) when I connect directly to the NIC on my Mac. Does this mean there’s something wrong with my router? I’m using a D-Link DIR-655, which is supposed to support gigabit.

It would highly suggest the bottleneck is at the router level.

Ok, now I’m getting 3-5 mb/s in some situations, but not others. And I’m not seeing a pattern, either. I’ve been testing by dragging & dropping large files (avis, mp4s, etc.) from my iMac to my Drobo and from my Drobo to my iMac. The former seems to transfer pretty quickly regardless of whether I’m using my router; whereas, the latter sometimes (not always) transfers quickly when my Drobo is connected directly to my iMac, but always slows to a crawl when my Drobo is using my router. I have no idea what’s going on here…[hr]
Oh, and I should have mentioned that I’m getting very fast transfers from my iMac to my PC (and PC to iMac), which are connected through my router. If it was a router problem, I would expect these transfers to be slow as well, right? It makes me wonder if the problem is the network protocol. Everything seems to go smoothly when SMB is being used (e.g., iMac -> PC, or PC -> Drobo), but when AFP is used (iMac -> Drobo) things get patchy. Is it possible that there’s some sort of conflict between my router and AFP?

Just a quick update, in case anyone else experiences similar issues with their Drobo FS and a DIR-655 router: I resolved the transfer speed issue by plugging my PC into ethernet port 1 (on my router), my Drobo into port 2, and my iMac into port 3. With the Drobo in port 1 (or 3), whichever computer is plugged into port 3 (or 1) gets horrible transfer speeds; but, with the Drobo plugged into the middle port, everything is nice and snappy (around 25-30 MB/s).

I am having similar issues, Hookflash. My Windows 7 box smokes my MacBook Pro using WiFi. Even the initial connection establishment is night and day difference. Windows 7 authenticates in less than 5 seconds; MBP can take up to and sometimes over a minute to do the same. I have a WRT610Nv2 running DD-WRT.

I also have a D-link DIR-655 router and am experiencing really slow transfer speeds using OS X. Plugging the DroboFS or computer into ports 2 and ports 4 don’t fix the problem, however.

I’m not quite sure what’s going on, but I think it might be an issue with my Drobo. Occasionally, I’ll get fast read speeds, but I don’t know when or why this happens.

I’ve tried different ethernet cables, but not a different router – but my router is supposed to be gigabit!

Do you get the same speeds when directly connected to the NIC card on your computer?

Hi, it was the same speed when directly connected to the NIC card on my computer. However, I solved the problem. I was using the Transmission app for DroboApps and once I killed the process, the read speed returned.

Brand new drobo fs, 2 2TB drives, on gigabit connection, transfer of 1.5 TB of data, estimated 18 days.

Current rate now is approx 1MB per second.

At this rate, will take me months to copy over, when I add the other drives… holding off on purchase now, to see if anyone else has these issues.

The switch I have between devices is pushing over 300Mps to a different device right next to the drobo.

If it’s brand new, you’re probably hitting a lot of overhead as it lays out the drive. However, if such speeds persist that’s abnormal. Large file transfers over gigabit should be in the 20MB/sec sustained range; small files, however, are massively slower, and that’s just the nature of small files on any I/O system.

Make sure you have firmware 1.2.1 installed on the DroboFS. Then try connecting the DroboFS direct to your computer, making sure both the NIC and DroboFS are using compatible IPs and the same subnets masks, to see if the transfer is faster when the network is eliminated.