Consolidated Business & Enterprise Computing Rant Thread

Discussion in 'Business & Enterprise Computing' started by elvis, Jul 1, 2008.

  1. BoutS

    BoutS Member

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    I suppose the tolerance of skull fuckery (to quote a prominent user) is considerably lower here, than in WP.

    Was an interesting thread, where they state very minor differences don't usually break stuff.
     
  2. millsy_c

    millsy_c Member

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    Can you say why it's so time critical? I'm genuinely curious if it isn't a troll.
     
  3. Foliage

    Foliage Member

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    I'm with Maqaurie however it feels a bit cheap. Do you use www.access-online.com? I get the feeling ours is outsourced for yellow brick road and something different to what other people get.
     
  4. Foliage

    Foliage Member

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    Define "keep time" ?
     
  5. OP
    OP
    elvis

    elvis Old school old fool

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    As opposed to the freely available NTP documentation written by experts on machine time keeping?

    Turns out that's well covered in the NTP documentation. Sad. (Protip: keep time on the hypervisor itself, and force VMs to stay in sync with that, which is what EVERYONE does. You ever head of Amazon? Jeff Bezos? Richest man in the world? Yeah, guess how the several billion VMs they run keep time...)

    Also, it turns out the documentation has information on how NTP deals with latency and measures it to compensate for delays between the time keeping device and the client to ensure said latency doesn't impact on time accuracy.

    But, hey, instead, go ask randoms on a forum about manually doing something you should have made automatic because you didn't read the doco to understand how it actually works.
     
  6. OP
    OP
    elvis

    elvis Old school old fool

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    I use the Android app. NFI who wrote it, but it craps all over the Westpac Android app.

    Also, fuck I hate the word "app".

    [​IMG]
     
  7. mesaoz

    mesaoz Member

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    VM's can pull their time from NTP or from the hostmachine...

    edit: elvis beat me
     
  8. ^catalyst

    ^catalyst Member

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    Luke212 on NTP :

    [​IMG]
     
  9. asho444

    asho444 Member

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    You missed Shortcut

    I F*%king hate shortcuts being called apps
     
  10. NSanity

    NSanity Member

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    Yeah/Nah...

    https://blogs.vmware.com/apps/2016/01/completely-disable-time-synchronization-for-your-vm.html - this is the most current doco - but like I say below, I've been reading this since ESXi 5 was new.
    https://blogs.msdn.microsoft.com/virtual_pc_guy/2010/11/19/time-synchronization-in-hyper-v/

    TL;DR - ever since like... ESXi 5 (which is when I started to care about such things - maybe longer) its been ignore the host, go external - and where possible use a physical box for your PDC Emulator role (which in AD speak is the time authority for the domain).

    * Don't use Guest Services
    * use NTP, and
    * hammer the thing far more frequently than the OS defaults (15 minutes i believe is the initial suggestion).

    And if you need sub second accuracy, you probably can't achieve it reliably on virtualised hardware
     
  11. OP
    OP
    elvis

    elvis Old school old fool

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  12. PabloEscobar

    PabloEscobar Member

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    High Frequency Trading... Written in Java, running on some shitty VPS that is oversubscribed out the Wazoo. :).

    How should you be framed? You come across issues and ask about solutions, and then when you are provided with the solution... dismiss it.


    the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom



    Not EVERYONE...

    In a windows domain for example, you want your PDC emulator to be configured as the authorative time source, (its up to you how you get that time), and then all domain members update time from that.

    But then you also need to be aware of the limitations of that :). (http://forums.overclockers.com.au/showthread.php?t=1227610)
     
  13. NSanity

    NSanity Member

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    I can see eye to eye with you that ESX is overrated. Certainly when you mix in the $ for licensing anything of value on it.

    Hyper-V is free though. And more than capable.

    But if 2 of the main hypervisors are suggesting this is the best way to do timekeeping - and Microsoft is with regards to DC's. Then chances are its not without merit. As you say, let NTP manage the lot. Fuck the hypervisor/host - its probably lying.

    KVM still doesn't do a bunch of shit that both ESX/Hyper-V does. FWIW.
     
  14. OP
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    elvis

    elvis Old school old fool

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    I was talking specific to VMs rather than desktop OSes on bare metal on a domain. (And for what it's worth, we buck the trend here and tell our Windows desktops to sntp sync against a couple of hardware Linux boxes rather than PDCs. #yolo ).

    But yeah, Windows time is pretty terrible in general. BSD can get down to 10^-6 accurate (as in, real accuracy, not just time stamps with extra digits). Linux recently changed from 10^-3 to 10^-4 to support high volume trading (as a bunch of large stock markets all run off RHEL these days). Desktop Windows is still stuck at 10^-2 accuracy (again, don't confuse actual accuracy with how many digits you see in your time stamps, as those digits are largely arbitrary if the underlying OS doesn't have its shit together).

    ITYM libvirt. That's the bit that folks generally consider to be the platform. KVM/QEmu is just the hypervisor part, and quite genuinely craps all over ESXi for raw performance (yes, even modern versions available today).

    We replaced our VERY old VSphere setup about 2 years back with an oVirt 3.6 setup. For our very trivial needs (basic availability clustering and failover management, snapshots, SDN, blah blah boring) it more than succeeds as a production replacement. At time of writing, 4.1.4 is out, and has added a tonne more stuff we'll never ever need (although I'd still like to upgrade ours at some point).

    Best of all, fuck your licensing costs.

    It *is* Linux though, which makes Luke212 angry because all Linux sysadmins are overpaid job-protectionists. For that market, I can totally see the appeal in Hyper-V. And for the little I've used it (Server 2012r2), it was quite impressive. I'll be interested to see what VMWare do to not be commoditised out of their market. As a colleague of mine said some years back: "the Netscape of virtualisation". :)
     
    Last edited: Aug 14, 2017
  15. Lou

    Lou Member

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    Being one of the 'Big 4' their arses are too far up their own arses to look at what the 'lower' competition is doing.
     
  16. PabloEscobar

    PabloEscobar Member

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    As long as your pdc emulator syncs against that source as well, all is good with world.


    The digits are arbitrary as soon as your displaying something that is beyond the precision of the instrument measuring it. In a VM, The virtual "hardware" clock can't be relied upon, so if you need more accuracy than NTP or PTP provides, you pass through a hardware RTC, and read from it.
     
  17. NSanity

    NSanity Member

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    Which is why i predominantly prefer Hyper-V.

    When you're talking 4-5 figures per host in terms of licensing difference - JUST to run things (and have commoditised things like live migration and the like) - If i don't need your specific feature, you can fuck off.

    If Hyper-V itself wasn't free, or i didn't predominantly work with Windows (and thus have the windows suite of "stuff") I'd probably work with KVM/Libvirt/ovirt/whatever RHEL calls it.
     
    Last edited: Aug 14, 2017
  18. OP
    OP
    elvis

    elvis Old school old fool

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    Yeah, everything talks to them. And we have a couple of nominated ones in each site that sync with each other over the WAN too (as well as the usual au.pool.ntp.org members), so the spread is pretty good.

    I'm not a card carrying member of the time-nuts mailing lists or anything, but getting NTP "right" is the first thing I try to do in any site I turn up to.

    I've never gotten to the point of setting up my own GPS time source. Always been a little project I wanted to do for shits and giggles. Given you can buy an ntpd-compatible GPS receiver off dx.com for $40, it wouldn't be too hard. Hell, plug that into an RPi-Zero-W and you're laughing.

    http://doc.ntp.org/4.2.6/drivers/driver20.html
    https://area-51.blog/2012/06/18/getting-gps-to-work-on-a-raspberry-pi/

    RHEV-H is the Hypervisor (aka KVM/QEmu).
    RHEV-M is the Manager (aka oVirt).

    https://keithtenzer.com/2015/01/08/...ement-rhev-m-overview-apis-and-code-examples/

    Remembering that libvirt is hypervisor agnostic, so it can actually manage a bunch of ESXi hosts (or most things, excluding Hyper-V) if you want.
     
    Last edited: Aug 14, 2017
  19. NSanity

    NSanity Member

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    For me, its either that, DNS or Backups.

    Seemingly wherever I go...
     
  20. OP
    OP
    elvis

    elvis Old school old fool

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    Fucking A. DNS seems to be ancient hieroglyphics to some sites I've walked into. How the fuck people (as in, paid professionals whose job it is to make this shit work) still don't get that, I'll never know.
     

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