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为cpu超过订阅确定合适的方法

  • 2021年2月2
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米
  • MarvinB
  • “航行者”号
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我们对Nutanix很陌生。我们正在从ESXi迁移到AHV。我们目前在ESXi上有一定程度的CPU超额订阅。我们预料到一些集群需要超额订阅CPU，我正在寻找安全做到这一点的方法。我看过最佳实践指南，但内容很少。任何帮助都将不胜感激。

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最佳答案伊万诺夫2021年2月3日16:25

There is no difference for the AHV hypervisor whether it\u2019s vCPUs or cores per vCPU in the VM config.<\/p>

We always recommend to use vCPUs first, so if you need a VM with 4 CPUs in total - just use 4 vCPUs and 1 core per vCPU. The only purpose of those settings is that some older guest operating systems have limitations in the amount of cores and\/or sockets, so for legacy OSs it might be useful. Also, some software is getting licensed by the amount of sockets, then it might be useful to use multiple cores per vCPU to get less sockets. For performance there is no difference.<\/p>

\u00a0<\/p>","className":"post__content__best_answer"}">

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We are new to Nutanix. We are migrating from ESXi to AHV.\u00a0 We currently have some level of CPU\u00a0oversubscription in place on ESXi.\u00a0 We anticipate the need to oversubscribe CPU\u00a0on some clusters and I am looking for ways to do this safely.\u00a0 I\u2019ve looked in the Best practices guide but there was very little there.\u00a0 Any help would be appreciated.<\/p>","quoteUsername":"MarvinB","translations":{"Common":{"like":"Like","unlike":"Unlike"},"Forum":{"Quote":"Quote","Share":"Share"}}}">
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伊万诺夫
排名
Userlevel 4
徽章 ＋5

嗨MarvinB,

如果你从ESXi迁移到AHV，你可以使用与ESXi类似的CPU oversubscription。如果你是从非Nutanix迁移过来的，不要忘记，在Nutanix上，每个主机上也有cvm，有时会占用相当一部分的CPU资源，必须将其考虑在内。

通常，如果你目前在ESXi上有3比1的比例，你在那里没有问题，你也很可能在AHV上有3比1的比例没有问题。

通常，对于物理核与虚拟核的比率，没有经验法则。这在很大程度上取决于您的工作负载和您运行的应用程序类型。例如，对于SAP HANA或非常繁重的OLTP数据库，最好不要超额订阅。对于小型数据库，某种形式的超额订阅是可以的，而对于VDI，超额订阅可能更高。如果您运行特定的工作负载，例如SQL、Oracle等，您可以在门户上查看我们针对这些解决方案的最佳实践https://portal.nutanix.com/page/documents/solutions/list．

总的来说，我会说:

  • 关键任务负载可采用1:1比例，保证虚拟机在需要时访问CPU
  • 1:1-3:1可用于一般用途的工作负载
  • 3:1-5:1可以用于VDI或一般用途的工作负载，但根据vm的繁忙程度，可能会出现CPU争用
  • 5:1和更高——随着调度开销的增加，显著的性能影响的机会也会增加

但不要把它当作一个规则。这只是一个基于平均工作量的粗略估计。

Sr. SRE | Nutanix全球支持| NSS #464, NCAP, VCP6.5-DCV, RHCSA, CCNA, EMCSA, AWS和谷歌云认证
Hi MarvinB,<\/p>

if you are migrating from ESXi to AHV you can use similar CPU oversubscription as on ESXi. If you are migrating from non-Nutanix, just do not forget that on Nutanix there are also CVMs on each host that can sometimes utilise quite some part of the CPU resources and they have to be taken into account.\u00a0\u00a0<\/p>

Typically, if you currently have for example 3:1 ratio on ESXi and you have no problems there, you most likely also will have no problems with 3:1 ratio on AHV.<\/p>

In general, there is no rule of thumb for the physical-to-virtual cores ratio. It depends a lot on your workload and what kind of applications you run. For example, for SAP HANA or very heavy OLTP databases it might be better to not oversubscribe at all. For small databases some kind of oversubscription can be ok and for VDI it can be much higher. If you run specific workloads, such as for example\u00a0SQL, Oracle, etc, you can check our best practices for those solutions on the portal -\u00a0https:\/\/portal.nutanix.com\/page\/documents\/solutions\/list<\/a>.\u00a0<\/p>

In general, i would say:<\/p>

米

这很有帮助。接下来，是否有任何最佳的方法来设置vcpu /内核来帮助解决这个问题。如果我们有一个4个CPU的系统，设置为4个vCPU和1个核，2个vCPU和2个核，或者1个vCPU和4个核，会有什么不同吗?

That is very helpful.\u00a0 One follow up, is there any optimal way to set up vCPUS\/cores to help with this.\u00a0 Just with respect to oversubscription, would it make an difference if we had a 4 CPU\u00a0system set up as 4 vCPUS with one core, 2 vCPUs with\u00a02 cores, or 1 vCPU with 4 cores.<\/p>","quoteUsername":"MarvinB","translations":{"Common":{"like":"Like","unlike":"Unlike"},"Forum":{"Quote":"Quote","Share":"Share"}}}">
伊万诺夫
排名
Userlevel 4
徽章 ＋5

在VM配置中，对于AHV管理程序，无论是vCPU还是每个vCPU的核都没有区别。

我们总是建议首先使用vCPU，所以如果您需要一个总共有4个cpu的虚拟机—只需使用4个vCPU和每个vCPU 1个核。这些设置的唯一目的是，一些较老的客户操作系统在内核和/或套接字的数量上有限制，所以对于旧的操作系统，它可能是有用的。此外，一些软件是根据套接字的数量获得许可的，那么为每个vCPU使用多个核以获得更少的套接字可能是有用的。对于性能来说没有区别。

Sr. SRE | Nutanix全球支持| NSS #464, NCAP, VCP6.5-DCV, RHCSA, CCNA, EMCSA, AWS和谷歌云认证
There is no difference for the AHV hypervisor whether it\u2019s vCPUs or cores per vCPU in the VM config.<\/p>

We always recommend to use vCPUs first, so if you need a VM with 4 CPUs in total - just use 4 vCPUs and 1 core per vCPU. The only purpose of those settings is that some older guest operating systems have limitations in the amount of cores and\/or sockets, so for legacy OSs it might be useful. Also, some software is getting licensed by the amount of sockets, then it might be useful to use multiple cores per vCPU to get less sockets. For performance there is no difference.<\/p>

\u00a0<\/p>","quoteUsername":"Sergei Ivanov","translations":{"Common":{"like":"Like","unlike":"Unlike"},"Forum":{"Quote":"Quote","Share":"Share"}}}">

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