[iso1631]

I did spec a couple of 7m dacs a few months ago to run between two adjacent bays, but normally for more than 2m I'll just drop a SM sfp and run a preterminated fibre cable.

In the field its the armoured fibre on a reel, 100m, 200m, 500m etc, with opticon connectors, or some normal cat5 typically for APs

[bobdvb]

Some network guys I know prefer fibre even within the rack, just because they don't want the weight and the obstructions in the rack. Apparently more than once the weight of the DACs and the bulk of the cable bundle has caused a problem with NICs.

Personally that surprised me, but I can see where they're coming from.

[buildbot]

Yep, I did this for my little DGx spark cluster because 100-200gb copper cables are very thick, heavy, and annoying.

[mwpmaybe]

If you start doing bonded links with DACs or if you have a bunch of servers, the cable management situation gets ugly in a hurry, and the usual solutions like patch panels and keystones aren't applicable. Source: my basement

[bobdvb]

That's my home lab, it's ugly and I am starting to use MTP breakouts instead because those DACs get in the way so much.

[ragall]

> the usual solutions like patch panels and keystones aren't applicable

Why not ?

[mwpmaybe]

You can't punch down twinax and the connectors are too big for keystones.

[wmf]

Support brackets would be 10x cheaper than fiber.

[nucleardog]

Admittedly I'm not buying Enterprise Grade(TM) stuff, but...

For simplicity I just use 10G LR modules everywhere. A pair of fiber transceivers is $25. Pretty sure last batch of 3M pre-terminated fibre cables I was grabbing were like $3 a piece or something. So we'll round up and call it $30.

I can get a 3M DAC for about $20.

So yeah it's cheaper, but the price isn't _that_ different. I was using DACs in quite a few places (and still am), but in general I've found it easier just using fiber. (For one, I've had a few devices that didn't get along with various DACs but worked just fine with the fibre transceivers.)

[iso1631]

The fibre and sfps are a tiny price of the entire solution

DACs will be cheaper than fibre in a bay, but between neighbouring bays about the same.

A 7m passive 40g qsfp dac is £80. A pair of multimode 40g is £66 and 7m multimode cable is £10.

A 2m dac is £28, so fibre is 3 times the price.

[bobdvb]

And an extra £40~ per server is irrelevant if we're worried about an outage on £500k-£1.5m of gear and the services they provide.

[justsomehnguy]

If you do it only once and would never touch it - yes.

But the time spent on digging around and occasionally debugging what and where exactly came off and no longer links (at best) or there is still link up but the are too many errors, add some SLA on top of it... No.