Is iSCSI a feasible option for a home network SAN? How does iSCSI work? How do the drives interface with the ethernet? What are the options for Mac OS X?
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iSCSI & Mac OS X for Home Network Storage
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I'm hoping for better iSCSI support wiht Leopard.
iSCSI puts SCSI inside an IP wrapper. Typically it is added as a software "initiator" (fancy storage word for the SCSI device that is in the host) to speak to your iSCSI target (the device that is supplying disk to the iSCSI initiator)
So, a couple of things need to happen. You need to have an iSCSI target. There are a few free ones for Linux and Windows, that run as a "software target" on your server. There are hardware iSCSI solutions, typically in business environments only unless you are a total geek and spend 10's of thousands of dollars on storage for your garage.
The second thing that needs to happen is to have an iSCSI initiator for your Mac. There is one software initiator that I found, globalSAN, but I couldn't get it to work with the hardware target we have at work, so I abandoned it. I am not sure if there are any OS X drivers for the hardware initiators from QLogic. Those act like a SCSI card to the server/host, and offload the TCP checksums as well. Naturally those would only work in something like a Mac Pro with a PCI/PCI-X/PCI-E slot. For laptops, only the iSCSI software initiator will work.
In the software initiator case, it rides on top of one of your standard NICs. In the iSCSI HBA (hardware initiator) side, it has it's own Ethernet interface.
iSCSI puts SCSI inside an IP wrapper. Typically it is added as a software "initiator" (fancy storage word for the SCSI device that is in the host) to speak to your iSCSI target (the device that is supplying disk to the iSCSI initiator)
So, a couple of things need to happen. You need to have an iSCSI target. There are a few free ones for Linux and Windows, that run as a "software target" on your server. There are hardware iSCSI solutions, typically in business environments only unless you are a total geek and spend 10's of thousands of dollars on storage for your garage.
The second thing that needs to happen is to have an iSCSI initiator for your Mac. There is one software initiator that I found, globalSAN, but I couldn't get it to work with the hardware target we have at work, so I abandoned it. I am not sure if there are any OS X drivers for the hardware initiators from QLogic. Those act like a SCSI card to the server/host, and offload the TCP checksums as well. Naturally those would only work in something like a Mac Pro with a PCI/PCI-X/PCI-E slot. For laptops, only the iSCSI software initiator will work.
In the software initiator case, it rides on top of one of your standard NICs. In the iSCSI HBA (hardware initiator) side, it has it's own Ethernet interface.
OpenFiler is an opensource SAN solution that runs on standard hardware (it's Linux based) and provides an iSCSI option that's compatible with globalSAN's OSX initiator (you just need to remember to grant permissions properly, which is a bit "esoteric" on OpenFiler). I'm running a 2TB SAN on OpenFiler and globalSAN and it works perfectly under Leopard (including Time Machine use of the partition).
OpenFiler sounds very cool. I think I'll check it out. However, I noticed it's website lists support for CIFS, NFS, HTTP/DAV, FTP, iSCSI but NOT for AFP. So, with a setup like yours will I run into all the headaches such as metadata being stripped from my files, or errors when copying files with filenames that have special characters, etc.???
You won't actually be using CIFS/NFS/ETC. with OpenFiler. For your purposes you will be accessing it via the iSCSI protocol. That will present the filesystem to your Mac (via the GolbalSAN software) as a local disk. Your Mac will use it similarly to a USB or firewire drive.
Any Problems with your mac locking up when using globalSAN's OSX initiator?
Hi Phil,
I am using the GlobalSAN initiator as well for a 2TB RAID on openfiler 2.2 and I'm getting hard lock ups when transferring large amounts of data. I've tried monkeying around with the iSCSI-target settings in ietd.conf but I haven't found a solution yet. I still get lock ups and the forum for GlobalSAN has been slow. Any words of wisdom?
I'm using a Netgear GS801 8 port Gigabit switch between the filer and my MacPro.
Best,
Jeff
Hi Phil,
I am using the GlobalSAN initiator as well for a 2TB RAID on openfiler 2.2 and I'm getting hard lock ups when transferring large amounts of data. I've tried monkeying around with the iSCSI-target settings in ietd.conf but I haven't found a solution yet. I still get lock ups and the forum for GlobalSAN has been slow. Any words of wisdom?
I'm using a Netgear GS801 8 port Gigabit switch between the filer and my MacPro.
Best,
Jeff
Hmm, that's a bit strange! I'm using an almost identical setup except my gigabit switch is a D-Link one and have never had a lock up at all either in Tiger or Leopard and I regularly copy around hundreds of gigabytes of data. My OpenFiler setup is Out of the box with now tweaking of any settings (except to add the local lan subnet to the allowed list) What's locking up (is it OSX or OpenFiler)? Are you getting any log information anywhere?
EDIT: One thing that may cause problems is if you've changed the MTU from the default of 1500 to jumbo frames or similar: Some switches don't like having anything except the standard MTU setting
Mac Pro Locks up using globalSAN iSCSI Initiator
Hey Phil,
Quite interesting! Are you running it on a Mac Pro? I've done some more testing and using my Dual 2Ghz G5 Mac attached to the same switch I've had NO PROBLEMS at all. Same goes with attaching to the iSCSI LUN from my G4 PowerBook. I've copied 150GB of data to the iSCSI LUN on openfiler without issue. I'm wondering if it's something to do with the Intel binary of globalSAN's universal binary application... I'll check the MTU thing.. I recently changed the Mac Pro's MTU for better performance on my FiOS line but I'll put it back to 1500 and see what that does.. Thanks for the feedback!
Hey Phil,
Quite interesting! Are you running it on a Mac Pro? I've done some more testing and using my Dual 2Ghz G5 Mac attached to the same switch I've had NO PROBLEMS at all. Same goes with attaching to the iSCSI LUN from my G4 PowerBook. I've copied 150GB of data to the iSCSI LUN on openfiler without issue. I'm wondering if it's something to do with the Intel binary of globalSAN's universal binary application... I'll check the MTU thing.. I recently changed the Mac Pro's MTU for better performance on my FiOS line but I'll put it back to 1500 and see what that does.. Thanks for the feedback!
If you have some skills with UNIX, an option could be running a Solaris Express server.
It has all the cool features of ZFS (redundancy, safety, manageability and so on...) and allows you to enable ISCSI in a second.
I've tried it last week but without any good result. I'll try again as soon as I have some spare time.
Anyone have experience in a Solaris/OSX ISCSI setup?