DroboPro random iSCSI disconnects

Hi All,

I’m hoping someone here has an insight or has experienced the same issue could chime in.

Here’s the scenario:

We recently deployed a new storage setup consisting of the DroboPro and an Intel Xserve (6 CPU Nehalem, 6GB RAM) for file sharing.

So we put the new hardware in and decided to connect the DroboPro via iSCSI to the Xserve. It took many, many hours migrating their data from the old RAID to the DroboPro (had to copy the data to a FireWire 800 drive first, then to the Drobo). During this time the Drobo was rock solid and I was impressed with its performance. Satisfied, I decided to deploy the new solution and turned on AFP and SMB file sharing services to roughly 20 users, mostly on Macs.

Within a few days of the server deployment, a user called and said she had problems connecting to the server. I was able to VNC into the server and discovered the Drobo had disappeared from the system; Drobo Dashboard said “no drobos detected” even though the Drobo icon was on the desktop. tried to navigate the Drobo’s file structure and was greeted by the spinning beachball of doom.

Thought the issue was odd, so I tried to soft restart the server. No dice; the server hung presumably because it was trying to unmount the drobo that was no longer there. I had to hard reboot the Xserve. When the reboot finished, the Drobo reappeared on the desktop and the Dashboard showed its presence. Over the course of the next week, the same thing happened; after a day or so (or on the monday following the weekend) the drobo would disappear from the system and I had to hard reboot.

Switching over to FW 800, although slower, showed that the Drobo was rock solid; when on iSCSI, random disconnects happened with regularity.

I’ve tried different Ethernet cables, , disabling disk spindown, moving the Drobo from the iSCSI switch and connecting it directly to the Xserve’s onboard Intel ethernet, and even replaced the Drobo with another refurb Drobo running the latest 1.1.11 firmware (the other Drobo was on 1.1.5). Same issue occurred with both Drobos. The only things that remained the same were the OS (server 10.6.4), the Drobo dashboard version (1.7.3), and the 8 hard drives in the Drobo (WD RE4 2TB). Everything is connected to an APC rackmount UPS. I’ve already attempted to uninstall and reinstall the Dashboard with the same result.

I suspect there’s an issue with the Drobo’s iSCSI stack. I’m going to reboot the Xserve in 32-bit kernel mode to see if the disconnects go away.

Shortly after the first Drobo started disconnecting itself, I also brought Atto Xtend San to use with an Infortrend iSCSI unit; so far that setup has been rock solid.

I’ve already opened up a support case but was wondering if anyone had a similiar issue. Thanks in advance for any insights.

This happened to me too, with Drobo’s supplied Ethernet cable with a direct connection to a perfectly working Mac, but I switched to one of my own cable and the problem disappeared.

Have you tried ATTO’s initiator with other consumer-grade iSCSI devices? (e.g. QNAP, Netgear, Synology). The globalSAN product (from SNS) might be free, but has issues and is unreliable.

Yeah, tried both supplied cables and non-supplied cat6 cables, same issue.

I haven’t tried using the ATTO iSCSI stack with other devices yet, but i tried globalSAN before getting the ATTO. Major flaws for me was that it KP’ed an imac g5 during testing and does not seem to support 64-bit kernels.

I have had nothing but problems running a Mac in 64-bit mode with a DroboPro over iSCSI.

Even with everything updated to the latest firmware and software the performance was terrible. Booting into 32-bit mode has solved all my problems.

Hmm, that doesn’t sound good at all. I’ve read all the posts in this forum and there are other people having issues with Macs and DroboPro over iSCSI. I think that the next time we’re in the market for a storage solution, we might have to go look at other vendors.

While Drobo support seems competent, the lack of enterprise support worries me, especially when they’re pushing enterprise-esque products like the Elite. Other vendors guarantee 24-hour delivery of parts/units and offer spare parts for sale, while DRI only offers normal shipping.

I don’t know how much money you are willing to put into this, but the other vendors products I tried (Synology, Netgear and QNAP) were even worst.

The worst of the bunch was QNAP, in fact they recommend to their Mac-based clients to use globalSAN. :slight_smile:

After two days of KPs and file system corruption, as HFS support in Linux is rubbish, I sent the QNAP unit back to the vendor. Drobos are not especially fast, and the finicky iSCSI should be dealt with by Drobo, but at least it’s reliable (using a 32-bit 10.6 kernel).

Sad situation though, considering the price of these units I would have expected better solutions.

I used to have random disconnections on my DroboPro connected to an Intel iMac. Due to the fact that iMac have only 1 ethernet port, I have to connect the DroboPro to a netgear unmanaged 8 port gigabit switch first and use the Drobo Dashboard and the supplied initiator to connect via iSCSI (So, it’s not a direct connection to the iMac).

At first everything was fine but after a month I started to notice the iSCSI randomly disconnects. But I found when I unplug the power of the Netgear switch and replug it, this iSCSI disconnection problem subsides. So, I suspect that the CPU in the unmanaged switch may not be able to handle the DroboPro traffic, I bought another Netgear 8 port gigabit smart switch thinking the smart or managed switches usually have a faster processor… and the random disconnections never happened again. It’s been 6 months now and the drobopro is always online. BTW, I’m still using the ethernet cable that came with the drobopro, so my problem wasn’t about the cable.

Just some personal experience, hope it might help you in diagnosing your issues with the drobopro.


Thanks for the info. I’ve already ruled out the switch as the issue (a Cisco Catalyst), as the disconnects happen whether the Drobo is connected to the Cisco switch or via one of the Xserve’s 4 GigE ports directly. not to mention that the Infortrend unit is also connected to the switch and has not had any issues at all.

@hh83917…I have a QNAP that was temporarily behind a Netgear switch for a few weeks due to a networking upgrade. I had frequent disconnects for any transfer that took more than a few minutes (using AFP, not iSCSI). I assumed it was a QNAP firmware issue as they have had some problems with AFP and SMB in recent firmware. Today I removed the Netgear since the upgrade finished yesterday and haven’t had a disconnect since. So I think you’re on to something.

I mention this because I’m considering a DroboPro and iSCSI (the QNAP supports this as well). I’ve been testing the globalSAN as the ATTO initiator is too rich for my blood. :slight_smile: I can’t justify $200 for something that doesn’t really win me much more performance over AFP/SMB/NFS. I’ve not got a virtualized environment to deal with here and figured using a Mac mini server to share iSCSI targets with the rest of the network seemed like a good idea over using someone else’s stack (see above about firmware issues). I may rethink this. I could still use the DroboPro attached as FW800 and do much the same but my experience with FW800 on Drobo 2nd gen leaves a lot to be desired (and is why the QNAP was bought).

I once had a Netgear router go bad. It didn’t completely go out - it would just randomly lose packets. If it’s a ProSafe model, they have Lifetime warranty (even if you bought it before they upgraded ProSafe to Lifetime warranty) - just register it on Netgear’s site and call their support. They’ll send you a replacement. :slight_smile:

jmei- I see, so since it’s not hardware, it’s either driver/iSCSI initiator issue assuming you have the latest firmware. If not, maybe you got a lemon… Sorry I have nothing more to suggest, I hope the drobo support can help you out. Good luck!

bhiga- Yes, I believe that might also be what happened to my unmanaged netgear router as well, but the lifetime warranty really helps. I got a replacement and use it for other part of the network. Not that netgear is any better than other consumer type routers, but it’s just nice that they have lifetime warranty on the ProSafe line. And they are fairly cheap too…