4 ms·

CockroachDB's performance is dependent on time synchronization. If a node detects it's too far behind, it will commit suicide. However, before it detects it, t

CockroachDB's performance is dependent on time synchronization. If a node detects it's too far behind, it will commit suicide. However, before it detects it, there is a possibility of stale reads. https://www.cockroachlabs.com/docs/stable/recommended-production-settings.html#clock-synchronization https://www.cockroachlabs.com/docs/stable/recommended-produc...

jgalentine007 8y ago
Thanks for pointing that out - I have yet to rtfm and dive deep. I wonder how frequently time sync problems occur in virtual environments after ntp syncing - I've seen pretty erratic behavior on virtual active directory domain controllers even after syncing with hyper-v and vmware.
- brazzledazzle 8y ago
  It’s been a long time since I messed with domain controllers but I believe Microsoft used to have explicit guides for handling time on virtual DCs. At that time we kept around a a couple hardware DCs to be safe but I do remember having the VMware agent correct the time could result in some bad results. I think it was because it immediately fixed the time and didn’t slowly correct the drift but it’s been a long time so my memory could be off.
- amaccuish 8y ago
  Time shouldn't be a massive issue for AD no? It's a vector clock, not a UTC clock. The UTC clock is only used to solve conflicts no?
  - e12e 8y ago
    Why do you say that? I thought kerberos depended on timestamps +/- drift? https://tools.ietf.org/html/rfc4120#section-5.2.3 https://tools.ietf.org/html/rfc4120#section-5.2.3 Or do you mean some other part of AD?
    - amaccuish 8y ago
      It defaults to 5 minutes. I perhaps wrongly assumed the issue was within 5 minutes.
- gurjeet 8y ago
  Here’s their blog post on how they manage to live without atomic clocks. I’ve found at least one assumption of thiers that i don’t agree with, but notwithstanding that, it’s a good read. https://www.cockroachlabs.com/blog/living-without-atomic-clocks https://www.cockroachlabs.com/blog/living-without-atomic-clo...

jgalentine007 8y ago

Thanks for pointing that out - I have yet to rtfm and dive deep. I wonder how frequently time sync problems occur in virtual environments after ntp syncing - I've seen pretty erratic behavior on virtual active directory domain controllers even after syncing with hyper-v and vmware.

brazzledazzle 8y ago
It’s been a long time since I messed with domain controllers but I believe Microsoft used to have explicit guides for handling time on virtual DCs. At that time we kept around a a couple hardware DCs to be safe but I do remember having the VMware agent correct the time could result in some bad results. I think it was because it immediately fixed the time and didn’t slowly correct the drift but it’s been a long time so my memory could be off.
amaccuish 8y ago
Time shouldn't be a massive issue for AD no? It's a vector clock, not a UTC clock. The UTC clock is only used to solve conflicts no?
- e12e 8y ago
  Why do you say that? I thought kerberos depended on timestamps +/- drift? https://tools.ietf.org/html/rfc4120#section-5.2.3 https://tools.ietf.org/html/rfc4120#section-5.2.3 Or do you mean some other part of AD?
  - amaccuish 8y ago
    It defaults to 5 minutes. I perhaps wrongly assumed the issue was within 5 minutes.
gurjeet 8y ago
Here’s their blog post on how they manage to live without atomic clocks. I’ve found at least one assumption of thiers that i don’t agree with, but notwithstanding that, it’s a good read. https://www.cockroachlabs.com/blog/living-without-atomic-clocks https://www.cockroachlabs.com/blog/living-without-atomic-clo...