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Is it possible for a server/PC to attach directly to a single fibre channel arbitrated loop drive with a 40-pin interface?

For example, we'd like to run benchmarks on a HP EVA 5000 fibre channel drive, but do it independently of the EVA controllers.

If this kind of set up is possible, what adapters/cables are needed?

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Sun 280R servers had FC disks instead of SCSI disks as their internal disks. I think you're going to have a really hard time finding any modern devices that have internal FC disks short of some crazy server that's actually got a FC shelf and internal cabling that's normal FC cabling, but inside the chassis. (and with a 3000% markup from if you did it yourself.) –  chris Nov 7 '09 at 0:22
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What are you trying to achieve? This is not going to be a simple job, and I'm not sure what the benefit is? The performance of a single drive is generally well understood and the widely published, it's the controllers themselves like the EVA that can vary wildly between different manufacturers. The datasheets on the various Seagate drives for example are all available here seagate.com/ww/v/… –  Ewan Leith Nov 10 '09 at 10:40
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4 Answers

I want to say "yeah, FC is an extension of the scsi protocol. Plug it in, and go nuts", but we all know nothing's ever that simple. Because they designed the FC shell put around standard drives to only work on one system, there's no telling what kind of nonsense you'd see if you tried directly connecting a drive to an HBA.

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Yes, they're called "T cards"

Here's a store that sells them: http://www.cs-electronics.com/fibre-channel-adapters.htm

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That lets you connect a normal drive via fiber. He wants to connect a fiber drive to a server. –  Basil Jan 23 '12 at 21:00
    
No, the t-card linked will connect a fibre channel drive to a HBA if the HBA has an appropriate connector. –  ConcernedOfTunbridgeWells Mar 5 '12 at 14:27
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Yes, it'll work just fine.

Your best bet would likely be plugging the drive enclosure directly into the FC HBA. The HBA will then see all the drives on the loop.

If you don't have an enclosure, you'll probably need to get one.

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You can use an adaptor called a 'T-card'. This will typically have sockets for SFP connectors and allow you to connect a drive to a fibre channel HBA. More expensive models will have loop resiliency controllers that will allow you to unplug the disk. Another option might be to purchase a secondhand fibre channel JBOD off ebay.

By and large, the firmware in most F/C disks will play nicely in a JBOD hanging off a F/C HBA. However, it's worth noting that many SAN controllers use disks formatted with a 520 byte sector format where each sector holds some additional error correcting codes. Disks with a 520 byte sector format will not mount on Windows or Linux without low-level formatting the drives with a 512 byte sector, which will render them useless on their native controllers.

Some SAN controllers are picky about the firmware of the drives and will refuse to mount drives with the wrong firmware. Additionally, some firmware images use proprietary Loop Initiation Protocol (LIP) reset protocols or have other slight idiosyncracies, so some drive firmware images won't play nicely with controllers that are otherwise agnostic to the drive firmware.

Hitachi and LSI are notable for proprietary LIP reset behaviour, although Clariion, Netapp and generic firmware drive images are quite well behaved from this perspective. I've never done anything with HP EVA drives, so I can't vouch either way for them. I expect that it's also quite likely that your EVA disks will use a 520 byte sector format, so you probably won't be able to do anything with them on your PC.

Disks tuned for a SAN are often optimised at the firmware level to live in large arrays. SANs are many things, but fast is not necessarily their strong point. A large body of drives allows decent IOPS stats, but a SAN tuned for a general purpose workload will not necessarily provide especially fast I/O to any of its hosts.

Cache segmentation, retries and read ahead strategy are the major parameters you can tune on disk firmware that will affect benchmark performance. The firmware may also restrict mode page updates to the disk's operating parameters. For example, on a ST3146807FCV, Clariion firmware restricts cache segmentation to a minimum of 32 segments, where generic 'V' firmware will let you configure the disk with 4 or 8 segments and a more agressive read-ahead strategy, will provide much better sequential performance.

The 'V' firmware also defaults to a more liberal retry strategy where corrupt data is viewed as more acceptable on the streaming media applications that 'V' firmware is designed for. Clariion firmware has a much more conservative retry strategy and will attempt to re-read a block more times before returning an error.

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