Startum Value of ESXi host

[RanjnaAggarwal]

What is the startum value of esxi host for time sync?

[a_p_]

Assuming it is a typo and you are asking for the "Stratum" value, take a look at e.g. http://kb.vmware.com/kb/1005092

st: Stratum is a value representing the hierarchy of the  upstream NTP servers. Higher values indicate NTP servers further away  from the root time source. Values are relative, and can be set manually  by an NTP server.

André

[RanjnaAggarwal]

I checked it already but doesn't get any info related to startum

[a_p_]

Maybe "Clock strata" at http://en.wikipedia.org/wiki/Network_Time_Protocol better helps understanding the values.

André

[RanjnaAggarwal]

Esxi uses which startum 0,1,2 or 3? which one????

[mcowger]

The value will vary depending on how far from the time source it is.

A ESXi host would always be stratum 2 or higher, because its is network linked to a stratum 1 device.  If it gets its time directly from the stratum 1 device (e.g. a GPS clock or similar), then it would be stratum 2.  If it gets it from another server (most common) it would likely be stratum 3.

[RanjnaAggarwal]

As i know startum 1 computers are not GPS Clocks they are the time servers so how it can directly sync it from time server even they  can get the time from locally attached device?

[mcowger]

Stratum 1 devices ARE the GPS clocks:

The basic definition of a stratum-1 time server is that it be directly linked (not over a network path) to a reliable source of UTC time such as GPS, WWV, or CDMA transmissions.

[RanjnaAggarwal]

Check this out that's saying something else:-

Stratum 0

These are devices such as atomic (caesium, rubidium) clocks, GPS clocks or other radio clocks. Stratum-0 devices are traditionally not attached to the network; instead they are locally connected to computers (e.g., via an RS-232 connection using a pulse per second signal).

Stratum 1

These are computers attached to Stratum 0 devices. Normally they act as servers for timing requests from Stratum 2 servers via NTP. These computers are also referred to as time servers.

Stratum 2

These are computers that send NTP requests to Stratum 1 servers. Normally a Stratum 2 computer will reference a number of Stratum 1 servers and use the NTP algorithm to gather the best data sample, dropping any Stratum 1 servers that seem obviously wrong. Stratum 2 computers will peer with other Stratum 2 computers to provide more stable and robust time for all devices in the peer group. Stratum 2 computers normally act as servers for Stratum 3 NTP requests.

Stratum 3

These computers employ exactly the same NTP functions of peering and data sampling as Stratum 2, and can themselves act as servers for lower strata.

While NTP (depending on what version of NTP protocol in use) supports up to 256 strata, only the first 16 are employed and any device at Stratum 16 is considered to be unsynchronized.

Here is main link:-

http://en.wikipedia.org/wiki/Network_Time_Protocol

[mcowger]

Either way, the answer is the same.  Under those definitions, an ESXi host would still likely be stratum 2 or3.

[RanjnaAggarwal]

so it's not using 0 and 1?

[mcowger]

Well, given that the ESXi host is not a cesium clock, its not stratum 0.  Given that its not directly connected to a cesium clock, its not stratum 1.  That only leave it to be a stratum 2 or higher.