Thanks a lot for the detailed explanation,


> Hi. I have enabled the mounstats, nfs and nfsd collectors for the NFS 
> > side metrics but there is a plethora of metrics without any proper 
> > documentation. Can somebody help with which metrics would give me 
> > the reads and writes completed on a particular mount? Like we have 
> > node_disk_reads_completed_total for SSD and HDDs, is there any exact 
> > alternative for NFS to get the IO stats? 
>
> If you care about NFS client statistics, there is no exact analog 
> because NFS mount metrics are fundamentally at a different level than 
> disk IO statistics. Disk IO statistics are obviously at the level of 
> data (blocks) transfered, regardless of why they are transfered and 
> how much of the data will be used. NFS client mount metrics are at the 
> level of filesystem operations, and filesystem operations can have 
> unpredictable disk IO impacts. All NFS operations send data to the NFS 
> server and get data back from it, but some only (potentially) create 
> read disk IO on the server while others cause write IO. 
>
> To put together NFS client IO statistics that are useful to you, you 
> will have to figure out what you care about in all of this. Some of this 
> will be workload dependent; for example, if your workload mostly reads 
> and writes a small number of big files, the filesystem level read and 
> write IO (which you can get numbers on) is highly predictive of disk IO 
> on the server and probably of performance. If your workload spends a lot 
> of time creating and deleting small files, looking only at the bytes 
> read and written from those files is probably missing a lot of server 
> disk IO, especially write IO. 
>
 >> Yes, I need these IOs exactly that are caused by the NFS operations. 
Can you give me an idea on which Prometheus metrics can give me this?
 

> As for what the metrics mean, that is hard to summarize well here. 
> The 'mountstat' collector is the most detailed and more or less what 
> it is collecting is written up in: 
>
> https://utcc.utoronto.ca/~cks/space/blog/linux/NFSMountstatsIndex 
>
> >> This is quite useful. Thanks!

This is from 2013 and for NFS v3, not NFS v4, but I believe that not 
> much has changed in this area of Linux since then and NFS v4 is pretty 
> similar to NFS v3. 
>
> (Locally I have a program that significantly aggregates this information 
> on a per-mount basis, because we have a *lot* of NFS mounts and the raw 
> mountstats data for them all adds up to too many metrics for us.) 
>
> - cks 
>

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