VMware Solutions Discussions

ontap command to find busiest files (VMware)


My trusty 960C running ontap 7.3.3 is under increasing strain from the number of vmware guests that are running on it.

So in an effort to understand the problem a bit more, I'm trying to figure out which guests are using the most I/O . I can see which hosts are busiest with nfsstat , but I would really like to drill down to each the guest.

Is there an ontap command will show me which files are busiest on the filer? I think this would be a good proxy to look at when determining which guests (or which class of guests) is using up the bulk of the I/O . Any other techniques or suggestions would be most appreciated.

I suppose I could try to come at this from the VMware end too - but it seems that the performance data recorded from NFS datastores is patchy at best.


Graham Bucknell.



I don't know any tool for viewing the most active files from the top of my head.

but there is "nfsstat -d" which shows you misaligned vmdks, and these are more often than not the source of increasing performance problems (misaligned IOs multiply the IOs that your disks have to do)

On the ESX side there's ESXtop which can produce files that can be opened and viewed in windows perfmon. There you see the IO generated by each vm, or on each HBA/Datastore

hope that helps



Thanks for the reply Michael . Unfortunately the version of nfsstat doesn't print out the misaligned vmdks but I'm pretty sure it's a problem in my environment anyway. Should have a look at that.

Your ESXtop idea sounds good - seems like the only other way to come at this problem

Hi graham,

I d suggest that you would need to start looking around for unaligned VMs. In terms of IOPS there each IOPS

that resides on unaligned file systems will occur a cost of x4. So if you have 100 unaligned VMs they will

provided the IOPS profile of 400VMs. This is just to give you an idea, not to scare you. I did notice you ve got

a 960 so maybe dealing with this urgently would be beneficial for your environment.





you can install "esx host utilities 5.2.1" on your esx server. there are tools inside, which you can use to mbrallign your vmdk files and check if there need it. example : mbralign - tests and fixes VMDK partition alignment

else you can find out the starting off set of you windows server under "system information""components/storage/disk"


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