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I'm considering to build one with something like this:
(a chasis with two dual port multipath expanders)
(4 8-port plain SAS controllers, 2 for each backplane)
and 36 Seagate 3Tb SAS drives (ST33000650SS)
OS -- FreeBSD.

And it's very interesting:
How good expander sas backplanes and multipath configurations work with freebsd ?
How to locate a specific drive in the bay? (literally -- how to blink an indicator on the drive in freebsd)
How to detect a fail of a controller?
Will it work together at all?

I'm asking to share any experience.

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closed as not constructive by MDMarra, Zoredache, EEAA, Jeff Ferland, Chris S Sep 28 '12 at 2:48

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.If this question can be reworded to fit the rules in the help center, please edit the question.

Why not a Solaris ZFS derivative like NexentaStor or OpenIndiana? – ewwhite Sep 28 '12 at 5:48

Considering the storage card you've selected doesn't list as one of the operating systems they provide drivers for, I suspect you're going to have some trouble there.

Drive-blink is supported by the storage controller you select, and the software that comes with the controller. The expanders the SuperMicro boxes come with do support the standard signalling protocols, so its up to the controller at that point. And then it's just FreeBSD compatibility getting in your way.

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Backplanes are handled transparently by the SAS controllers. Be sure to use SAS 2.0 HBAs and Expanders for the most flexible, easiest configuration. FreeBSD is only vaguely aware of what's going on, and it certainly doesn't "need" to know.

Multipath, use geom_multipath and it's configuration utility gmultipath. See man gmultipath for more details. Ask specific questions if you have any problems, but the "automatic" configuration is pretty darn straight forward when using SAS disks (and even modern SATA disks with SAS controllers).

The light on the front is going to be much harder (along with all the other management functions)... Different "enclosures" have different management functionality and methods of accessing that functionality. There's SES (SCSI Enclosure Services), SESoI2C, SPI, SGPIO, SEBM (for SATA), and possibly other proprietary/custom solutions. I'd have to really dig into your setup to tell you any more than this generic stuff.

Slight side note: the utilities getencstat and setobjstat are user unfriendly tools that can usually read/write to these enclosure services. They depend on the enclosure or controller supporting the standard mechanisms though. Neither are part of the standard world as they're a bit half baked and need cleanup. iXSystems has worked with the community to develop these, they're good enough to be backend utilities to a web-gui, so they've stagnated a bit.

Also, that card you picked out has a Marvell 9480 chipset. Marvel is not open source friendly, quite the opposite really. Stick with LSI or Adaptec, both companies have actually contributed code to FreeBSD. Most cards are extensively functional at the minimum, though you should consider FreeBSD's HCL when picking cards/chips.

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