There’s another view you can add into Perf Advisor that provides another more overall and possibly more useful perspective than the standard three that you normally find in the documents. It breaks down what percentage of the total reads are coming out of the main system cache, the extended cache (Flash Cache), and the disk.

In the NetApp Management Console do the following:

Setup

Hosts > Select a controller > Data Collection > Edit

Disabled Counters

wafl > read_io_type (select and add to the right column to Enabled Counters)

Data Collection Details

Modify wafl retention to be longer than the default of 1 week if you’d like.

Custom Views

Select an existing Flash Cache view and edit it

Add Chart > Name the Chart (ex: Reads Served % or something) > Line Graph > Category: Wafl; Storage System: Controller_Name > Available Counters: Wafl > Cache + Ext_Cache + Disk (Add all three to the right). Save the view.

From: toasters-bounces@teaparty.net [mailto:toasters-bounces@teaparty.net] On Behalf Of Jeff Mohler
Sent: Monday, May 14, 2012 3:04 PM
To: Fletcher Cocquyt
Cc: Mailing Lists
Subject: Re: What is Flash Cache caching?

Thats good numbers!

You wont get per volume cache hits/etc, its a system wide pool..but you can use 'priority' to say that PER volume, you want it sticky (keep) neutral (reuse) or never (never) to store those vol blocks in cache.

Cache is always random IO, sequential IO is kept on disk..plenty fast from there and doesn't pollute the flash cache.

Your next step is a chart showing the cache hit types.   Level0, metadata, directory...etc.


:)

Good stuff you're showing there.

On Mon, May 14, 2012 at 12:56 PM, Fletcher Cocquyt <fcocquyt@stanford.edu> wrote:

We setup a custom view in NMC to show us the hit % and Disk Reads replaced per the Flash Cache Best Practices doc TR-3832.

Is it possible to get more granular information about what is being cached?

These are NFS data stores and one of the volumes is 500Gb of web content.

So the web team would be very interested to know the net benefit to them - eg how much are the apache instances benefitting.

We also have oracle instances, VMware volumes and would like per volume stats if possible

I guess I am looking for the ability to apply the custom view to different vFilers and see per volume hits and hit %, Disk Reads replaced 

We have the 1Tb card installed and see the Disk Reads Replaced topping out around 5000 - with one spike up to ~8500

Does this look like what others are seeing in a mixed workload environment like I described?

thanks,

Fletcher

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