MESSAGE
| DATE | 2016-04-28 |
| FROM | Rick Moen
|
| SUBJECT | Re: [Hangout-NYLXS] What is a U (other than a letter in the
|
Quoting Ruben Safir (ruben-at-mrbrklyn.com):
> What is a U?
As Jay Ward would say, Wossamotta U?
(Seriously, Ruben, have you forgotten all about how to use a search
engine?)
'U' is a shortened form of 'RU' for 'Rack Unit', as used in 19-inch
(server) or 23-inch (telco) electronic equipment racks. I'm not sure
who decided a 1U of height would henceforth be set at 1.752 inches =
44.50 mm, but it was probably a telephone company engineer in the early
20th Century.
So, that definition of 1U is what we're stuck with. Which means you can
store a total of 42U of equipment height in a rack if it is designed to
accomodate just over 6' worth of gear, which they typically are.
That, in turn, and the economics of data centres, put pressure on those
of us working in server manufacturing to cut server height to 1/2U or
1/3U (as some gear now is, and with fans screaming like banshees to
prove it), or to sidestep that problem by switching to blade servers.
Note that the 'U' measure is the distance between the mounting of
consecutive vertical units, but the actual height of each such unit is
necessarily slightly less. E.g., a 1U server will not be exactly 1.752
inches tall, but rather 1/32" less than that, to allow some spacing.
[Panix press release:]
> If you have a specialized server strategy, or would like to administer
> your own machine without the added cost of a leased-line connection, you
> can colocate it with Panix.
A time-honoured option from a time-honoured company.
Or you can save a ton of money by paying a VM vendor, instead, and live
with the compromise of sharing vendor-provided CPU and RAM resources
with other customers' VMs.
You would still need to separately buy Internet access to/from your
house / apartment, of course. Personally, I run aDSL to my house,
pay that vendor (Raw Bandwidth Commmincations) for a /29 CIDR block of
static IPs, and run servers at my house.
I certainly _could_ move all my server presence to a VM vendor and use
only cheap dynamic-IP service to my house, but I enjoy the greater
degree of local control using physical servers on my own premises makes
possible.
Your Mileage May Differ.[tm]
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