5 ms·

> While building our Time Appliance, we also invented a Time Card, a PCIe card that can turn any commodity server into a time appliance. Invented? These cards

> While building our Time Appliance, we also invented a Time Card, a PCIe card that can turn any commodity server into a time appliance. Invented? These cards have been around. e.g. Meinberg makes a variety of expansion cards which use various time keeping sources such as WWVB, IRIG-B, GNSS, etc.

tyingq 5y ago
Those have the external source but don't seem to have the internal reference (Rubidium, Cesium, etc) for holdover. FB seems to be claiming to have invented a PCI card that makes a commodity server into a Stratum-1 source. Meinburg sells that too, but in proprietary appliance form.
- abyagowi 5y ago
  Again, invented might be too strong. This is an abstraction of what you need minimally to build a time server on an open source basis. We appreciate and are humble to other products in the market
  - tyingq 5y ago
    The availability of a much cheaper product than the appliances will likely create a bit of stir with competitors. The article mentions better management functions too. So perhaps invented is too strong, but it's more notable than your follow up comments suggest.
KaiserPro 5y ago
I read it that they've invented a product called time card, rather than the concept. Its an accurate and stable clock source. which is an important distinction. The Meinberg PCI cards appear not to have a local clock source thats well disciplined (ie a temperature compensated oscillator) Having an accurate time source that is updated once every second (typically) with a 1pps GPS is grand for most things. But if you need a stable clock as well, then you want a tiny atomic clock onboard as well. This is so you can run a clock source for an entire datacenter, or local section.
amelius 5y ago
What sounds like the most reasonable strategy to me is to have a single atomic clock in every datacenter, and then some basic hardware in every server to communicate with it.
- myself248 5y ago
  Which is exactly how the telephone industry has done it for decades, it's called a "building-integrated timing supply", or BITS clock. Typically this is a GPS-referenced clock with a local quartz or rubidium holdover oscillator, and output cards with dozens or hundreds of outputs serving various machines in the office.
  - amelius 5y ago
    Curious, why did telephony require such accurate clocks?
    - IggleSniggle 5y ago
      Not in telecommunications, but I do know that there are synchronous comm networks that don’t require any kind of sentinel / delimiter because there is a guarantee that the voltage will agree. My signals background mostly comes out of music, so somebody else probably has a better answer. But any time you need to convert between digital and analog signals relatively seamlessly, ie, introducing minimal processing overhead, you’re going to run into these kinds of issues. In that regard, you can think of telecoms as a CPU, and just like in a computer, you need a system clock that the entire architecture agrees on. First likely application that comes to my mind is VoIP.
      - sennight 5y ago
        It is one of those problems that is really easy to ignore, until you can't. I was using a cheapo 8051 based logic probe the other day and had a lot of fun dealing with not only jitter of two different oscillators (probe + device under test) - but differences in response time between probes (within the same sample period). If you ever find yourself wondering much influence your MCU's 4 clock cycle per instruction architecture has on the waveforms you're looking at... you're about to have a very bad time.
abyagowi 5y ago
Please excuse the language “invented”. We simply meant “came up with a form factor” of having the MAC+GNSS present via PCIe bus as a POSIX clock similar to a NIC with hardware timestamping. We are humble to all the awesome products that are out there and we just wanted to present an open source version of a simplified approach to allow others to build on it.
- jandrese 5y ago
  Isn't this a Symmetricom card? Being open source is the killer feature here. There are a number of companies that make PCIe timing cards, but they are all proprietary and go out of support way too quickly.
  - abyagowi 5y ago
    Yes, with the difference on how to present the time to the system, just a PHC

tyingq 5y ago

Those have the external source but don't seem to have the internal reference (Rubidium, Cesium, etc) for holdover. FB seems to be claiming to have invented a PCI card that makes a commodity server into a Stratum-1 source. Meinburg sells that too, but in proprietary appliance form.

abyagowi 5y ago
Again, invented might be too strong. This is an abstraction of what you need minimally to build a time server on an open source basis. We appreciate and are humble to other products in the market
- tyingq 5y ago
  The availability of a much cheaper product than the appliances will likely create a bit of stir with competitors. The article mentions better management functions too. So perhaps invented is too strong, but it's more notable than your follow up comments suggest.

KaiserPro 5y ago

I read it that they've invented a product called time card, rather than the concept. Its an accurate and stable clock source. which is an important distinction. The Meinberg PCI cards appear not to have a local clock source thats well disciplined (ie a temperature compensated oscillator) Having an accurate time source that is updated once every second (typically) with a 1pps GPS is grand for most things. But if you need a stable clock as well, then you want a tiny atomic clock onboard as well. This is so you can run a clock source for an entire datacenter, or local section.

amelius 5y ago

What sounds like the most reasonable strategy to me is to have a single atomic clock in every datacenter, and then some basic hardware in every server to communicate with it.

myself248 5y ago
Which is exactly how the telephone industry has done it for decades, it's called a "building-integrated timing supply", or BITS clock. Typically this is a GPS-referenced clock with a local quartz or rubidium holdover oscillator, and output cards with dozens or hundreds of outputs serving various machines in the office.
- amelius 5y ago
  Curious, why did telephony require such accurate clocks?
  - IggleSniggle 5y ago
    Not in telecommunications, but I do know that there are synchronous comm networks that don’t require any kind of sentinel / delimiter because there is a guarantee that the voltage will agree. My signals background mostly comes out of music, so somebody else probably has a better answer. But any time you need to convert between digital and analog signals relatively seamlessly, ie, introducing minimal processing overhead, you’re going to run into these kinds of issues. In that regard, you can think of telecoms as a CPU, and just like in a computer, you need a system clock that the entire architecture agrees on. First likely application that comes to my mind is VoIP.
    - sennight 5y ago
      It is one of those problems that is really easy to ignore, until you can't. I was using a cheapo 8051 based logic probe the other day and had a lot of fun dealing with not only jitter of two different oscillators (probe + device under test) - but differences in response time between probes (within the same sample period). If you ever find yourself wondering much influence your MCU's 4 clock cycle per instruction architecture has on the waveforms you're looking at... you're about to have a very bad time.

abyagowi 5y ago

Please excuse the language “invented”. We simply meant “came up with a form factor” of having the MAC+GNSS present via PCIe bus as a POSIX clock similar to a NIC with hardware timestamping. We are humble to all the awesome products that are out there and we just wanted to present an open source version of a simplified approach to allow others to build on it.

jandrese 5y ago
Isn't this a Symmetricom card? Being open source is the killer feature here. There are a number of companies that make PCIe timing cards, but they are all proprietary and go out of support way too quickly.
- abyagowi 5y ago
  Yes, with the difference on how to present the time to the system, just a PHC