Just adding my 2c to "4. Tip For UNIX sites":
All necessary unix/linux packages should be installed before the first invocation of 

Do run^pButtons(<any profile>)

otherwise some commands may be missed in ^pButtons("cmds"). I've recently faced it at the server where sysstat wasn't installed: `sar -d` and `sar -u` commands were absent. If you decide to install it later (`sudo yum install sysstat`in my case), ^pButtons("cmds") would not be automatically updated without little help from you: just kill it before calling the run^pButtons().

This is actual at least for pButtons v.1.15c-1.16c and v.5 (which recently occurred on ftp://ftp.intersys.com/pub/performance/), in Caché 2015.1.2.

Rdratio is a little more interesting — it is the ratio of logical block reads to physical block reads.

Don't you think that zero values of Rdratio is a special case, as David Marcus mentioned?
In mgstat (per second) logs I have at hand I've found them always accompanied with zero values of PhyRds.

Murray, thank you for the series of articles.

A couple of questions I have.

1) Documentation (2015.1) states that Rdratio is a Ratio of physical block reads to logical block reads,
while one can see in mgstat log Rdratio values >> 1 (usually 1000 and more). Don't you think that the definition should be reversed?

2) You wrote that:
If you do see high PhyRds on your system there are a couple of strategies you can consider:
...
- Long running read only reports, batch jobs or data extracts can be run on a separate shadow server or asynchronous mirror to minimise impact on interactive users and to offload system resource use such as CPU and IOPS.

I heard this advice many times, but how to return report results back to primary member? (ECP) mounting of remote database that resides on primary member is prohibited on backup member, and vise versa. Or these restrictions does not apply to asynchronous members (never played with them yet)?
 

Hi Mark,

You are right, in our setup Cache' is able to remove/assign the VIP to whichever node is the primary mirror member. All production traffic goes through ECP, so the mirror's VIP is used to simplify some administrative tasks only (just to recognize primary node quicker).

Virtual router is a standard component of vCloud Director, so called Edge Gateway. It sits between a single external address and internal load balancer implemented as a couple of Linux based VMs, each of which has haproxy for balancing and ucarp for VIP/failover. Load balancer distributes incoming client connections among several ECP application servers (Linux based VMs as well). 

That's how it works, in short. If somebody is interested in more verbose description, I could write more about it.

Regards,
Alex