10m active optical SFF-8644 to SFF-8644 $39

[nabsltd]

In another post, I was talking about how the limit on SATA cable length could make it hard to use an internal HBA with a bracket adapter to external, because the total cable length between active components could easily be longer than 1m (HBA→bracket→external cable→bracket→backplane) . When I started researching, I found that active optical cables for SAS were insanely expensive...generally over $200 as a base (for the pair of transceivers) plus $10-50 per meter. I did find a 10m shipped straight from China for $150, but then I found this:

https://www.amazon.com/dp/B00ZGYBL1M/

This cable will work with any LSI HBA with an external SFF-8644 and an "ACM" version of the firmware (like the 9300-8e).

 

[nexox]

That's a cool find, but are you not using an expander backplane? Seems like still kind of expensive to attach four SATA drives.

 

[soaringswine]

33 ft for $40?? That’s amazing but honestly what is the use case here?

 

[Koop]

Nice! That's a pretty dang far distance.

 

[Megamax667]

I think there are some other options too. I've had this dell equivalent on my ebay watchlist for a while: Dell Fibre Optic Patch Cable Mini SAS-SFF-8644 OM3 50/125 8-Core 30" 2409Y R22VC | eBay
And while I was going back to find that, I also saw this in the recommended which looks like the 25M version of the HP one for only a few bucks more: 793447-001 HP 82ft 12Gb Mini-SAS HDD Active Optical Cable 713533-004 *New Bulk* | eBay

Not an endorsement necessarily and no idea on any of the compatibility of them; I've never used them myself. Just figured they were worth a share.

 

[nihonjin]

Nice.

 

[Cruzader]

33 ft for $40?? That’s amazing but honestly what is the use case here?

Last time i used them was a client with a row of 2U4N units they wanted shelves added onto.

Shelves had to go in next/new rows as redoing main one was not even a topic.

 

[nabsltd]

That's a cool find, but are you not using an expander backplane?

I don't know how much the signal might degrade before it hits the next active component. SATA should be encapsulated inside SAS, so the length limit is longer, but in the world of twisted-pair networking, every coupler counts as quite a few feet of cable.

So, if you use the example I gave (HBA→bracket→external cable→bracket→backplane), it might be that the 8m SAS limit would drop to 2-3m because of the connectors at the brackets. Those internal to external adapters usually have a PC board with traces between the two sets of plugs, so all the protection of the shielded cable is lost.

The use case might be if you have the storage controller node somewhere near you, but the JBODs with 60 disks each in another room.

For me, it was mostly the shock at the prices that some of the custom cable companies were charging.

 

[nexox]

it might be that the 8m SAS limit would drop to 2-3m because of the connectors at the brackets. Those internal to external adapters usually have a PC board with traces between the two sets of plugs, so all the protection of the shielded cable is lost.

I've run that setup with 2 and 3 meter external cables and SATA drives just fine, but beyond that I imagine it could get sketchy, though signal degradation from connectors and from cable length are different things and don't necessarily add up linearly. You still have differential pairs on the PCB, that's generally enough inside a metal chassis, as long as it's not total garbage.