iSCSI for Mac OS X?

CoffeePlease asks: "Is anyone aware of development going on for iSCSI drivers for Mac OS X? I really need this but it's only out for Windows and Linux so far. I can't use the Linux drivers - they might run, but only as a command-line process, and I need other software to recognize the drives."

Not to my knowledge

[Matthias Wiesmann]

• There is no mention of iSCSI on apple's site, and I never heard of apple supporting iSCSI.
• You cannot run Linux drivers on Mac OS X, drivers is one area where Darwin is very different from Linux. You might have more luck with BSD drivers.
• Running the drivers as command line makes little sense: drivers don't have much interfaces. You might need the command line to start or install drivers.
• Assuming an iSCSI driver existed for Mac OS X / Darwin, then the system could see a remote device and handle it. Assuming the file-system on this device would be supported by Darwin then all applications, with or without GUI would 'see' this file-system.

Re:Not to my knowledge

[Draoi]

You might have more luck with BSD drivers

Nope, unfortunately. File system drivers for MacOS X would have to be written as a kext and would be IOKit-based. Totally un-BSD ...

My first point of call would be the Darwin-Drivers [apple.com] mailing list and archives.

iSCSI isn't even fully standardized!

[Anonymous Coward]

They just just just agreed on the final technical specs and most certainly haven't gotten to officially ratifying those specs as the standard yet.

iSCSI on Linux...

[molo]

Looks like there is a project that is implementing it as a kernel-level driver (as it should be, IMO). It exports the device as /dev/sda (etc.). It certainly seems to be in active development.

http://linux-iscsi.sourceforge.net/

oh, whatever

[Twirlip of the Mists]

Nobody "really needs" iSCSI. iSCSI isn't real yet. It's still one of those "coming soon" things, like Infiniband. And we saw how well Infiniband worked out.

iSCSI is just another way of solving a problem that's already been solved in any number of other ways. You need to attach a computer to some storage. Okay. You can use direct-attach FireWire storage. That has the advantage of being absolutely bullet-proof. Or you can use Fibre Channel to attach to a switched fabric. That works fine, too; just present a LUN to the Mac and let it format and mount it. Or you can use a network storage technology, like AppleShare or NFS. Those work fine, too, and the Power Macs, PowerBooks, and xServes are all shipping with 1000BASE-T, so that's not a problem.

There are any number of ways to ameliorate your so-called "real need" for iSCSI. These work today. Use them.

Re:oh, whatever

[Anonymous Coward]

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1) firewire - no managment, just loose drives attached to single machines. might as well suggest a usb memory stick. firewire drives don't make a san.
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no, firewire drives can be attached to many machines
at the same time. there -are- firewire san solutions out
there right now.

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2) fibre channel - cost of entry approaching $50k. that adds up to about 50k reasons not to use it on a home machine or small network.
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no, have a look at Apple's Xraid box. Much cheaper than
$50k.

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i think the real reason is that very few people are using macs in a data center serving up real applications to lots of clients - the sorta place where a well managed SAN makes sense. now that the draft standard has been finalized (but not ratified), i imagine that you'll see iSCSI becoming more commoditized and more software being made available for more OSs.
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I think the main reason that macs are doing that job
is that there haven't been any mac capable of doing
that job.

Re:Not to my knowledge

[questionlp]

It may not be Mac OS X or Darwin-specific, but it seems that Intel is working with Wasabi Systems/NetBSD [open-mag.com] to work on getting iSCSI to run on NetBSD. Some of this may work up to Darwin, then into Mac OS X... but it will take a while, mostly when Apple is focusing on Fibre Channel with their XServe RAID units.

Whoa. Are you confused.

[porkchop_d_clown]

As some writing SRP drivers for a living - iSCSI is a protocol that allows you to send SCSI commands between to machines linked by TCP/IP. It doesn't "bridge" IP and SCSI - it's not like you can use it to ping your hard drive.

The intent of iSCSI is to allow people to build SANs without having to shell out actual money for a fibre channel installation.

Re:oh, whatever

[benh57]

Your fibre channel numbers are way off. You can get an XServe RAID Fibre Channel and 2.5TB for $10999. The FC host PCI card from apple is $499. 400MB/s throughput.

Re:oh, whatever

[Anonymous Coward]

The 50K number isn't off the mark really. The $12,000 for XRAID buys you just two arrays attachable to two servers. If you want to put the XRAID behind one or two (for redundancy) fiber channel switches. Those run as much or more than the XRAID itself.

One of the benefits of iSCSI would be that the very pricey FC Switched network would be unecessary -- you could leverage your LAN.

Re:Not to my knowledge

[ZigMonty]

Incorrect. Although device drivers are IOKit-based, the VFS layer of darwin (filesystems) is almost straight FreeBSD. There are problems with the fact that Darwin's locking is different and probably VM issues. You definitely can't just take a FreeBSD filesystem and throw it into Mac OS X but it would only be a porting effort, not a rewrite.

Re:Not to my knowledge

[mkldev]

File system drivers for MacOS X would have to be written as a kext and would be IOKit-based. Totally un-BSD ...

If it were a file system, you would be wrong (since the VFS layer is basically BSD), but it isn't a file system; it's a block device. So yes, it would be an I/O Kit KEXT.

However, to say that it's "totally un-BSD" is a stretch. BSD drivers are relatively easy to port to Mac OS X if they are written correctly. The wrapper tends to be relatively small, with additional changes needed for synchronization where applicable.