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Question about pvs RAM cache and max ram

Jelle Vranckx



i am currently in the process of upgrading our xenapp 6.5 environment to a 1912 ltsr cu1 environment.

I have a question about max ram size setting in the vdisk configuration at the general tab.

where is this memory used? Is this on the ram of the pvs or on the target device itself?

The other setting we use is cache in device ram with overflow on HDD

We tried setting this to 7168 mb but we saw that our machines had some retries on pvs and we had some retries

the target devices has 90gb of ram and 16cpu's each. this because we would like to run 20 users on these machines which are running apps that require more memory.

our 2 pvs server has 384gb ram and 56 cpu's.


our hypervisors for the target devices has 384gb ram and 64cpu's.


We create a local hd for each target device of 100gb that can allso be used as ram cache.

Our page file is fixed 4gb.


i did some reading up lots of articles but it is so much information so what would be a best practice of ram configuration of page file ram cache size and others.


something else we saw was on a moment we were seeing lots of retries and freezes that the stand by memory on the prov servers was really high this was 260gb 

It was some time ago the prov servers where rebooted. After reboot of the prov servers  the standby memory was low and the performance seemed better.


i think it will be better that the prov servers are rebooted  more frequently but i am not sure there are other interventions or configurations needed like a bigger max ram cache size?


I hope somebody can give me more insight in this.


Thanks a lot.





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Wow, that is a lot of questions. I will try to help with a few.


The vDisk Maximum RAM Size is the amount of RAM that will be used on the target devices to cache the system disk writes prior to overflowing to hard disk. Sizing this is very specific to the workload of the target devices. As you indicated there are quite a few guides available online to help you work through this.


vDisk Statistics retries are a network issue, not a cache issue. A low number of retries relative to the overall disk activity is not uncommon.


Standby Memory usage on the PVS Servers is expected. This memory is utilized by Windows as a caching resource and is what allows PVS to reduce the number of reads back to the source vDisk.


We reboot our PVS monthly for patching. If you have an pair of PVS servers configured to the same vStore you can boot one at a time and not lose availability of your target devices. 

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