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A Pictorial Guide to vSCSI Disk Settings

July 12, 2016

One of the challenges of configuring virtual disks with the VIO server is knowing which settings must be changed during setup. I recently had something brought to my attention that should help clarify things.

It's from the IBM Redbook, "PowerVM Virtualization Introduction and Configuration." Go to page 498, and you'll find a diagram listing the different settings that need to be changed at each layer of the virtual environment. The pages that follow offer good explanations of what each setting means and why you'd want to change it. These settings are specifically for vSCSI disks.

Here are the proper settings in the client at the hdisk level:

    algorithm=failover
    reserve_policy=no_reserve
    hcheck_mode=nonactive
    hceck_interval=60
    queue_depth=xxx

Use these settings at the vSCSI client level:

    vscsi_path_to=30
    vscsi_err_recov=fast_fail

Use these settings at the hdisk level on the VIO servers:

    algorithm=load_balance
    reserve_policy=no_reserve
    hcheck_mode=nonactive
    hceck_interval=60

Use these settings for your fscsi devices on the VIO server:

    dyntrk=yes
    fc_err_recov=fast_fail

This Redbook clears up a number of other topics as well. There's an I/O virtualization overview, a planning section and an implementation section with examples. Processor and memory virtualization is covered in a similar manner. In addition, the authors hit on recent PowerVM enhancements, capacity on demand and the System Planning Tool.

To be sure, it's a lengthy document, but I'm willing to bet you will learn something -- likely, many things -- if you take the time to read through it.

Note: On a personal note, nine years ago this week -- July 16, 2007 -- was the date that AIXchange debuted.

For nine years, I've been writing these articles, one week at a time. When I scroll through posts from the fall of 2007, I can see the same themes pop up that still hold my interest today: education and tech conferences, virtualization, the HMC. I even wrote about an early demonstration of Live Partition Mobility.

Over time, I can see my writing "voice" evolve. Numerous times I wonder about you, the reader. The web stats say you're out there. I also know you're out there because occasionally, I'll do a web search and one of my posts that I'd long forgotten about will pop up as the answer to my query. I admit, I feel a sense of accomplishment from this sort of thing.

Still, it would be nice to be able to get a better feel for who you are. How did you find this blog? Which topics most interest you? Why do you keep reading? If you once read this blog but do no longer, why did you stop?

I'm often asked how I find things to write about, but honestly, it isn't that difficult. There's AIX and Linux and IBM i, servers and storage and virtualization, Redbooks and other documentation, and commands and scripts (did I mention I love scripts?). Plus I talk to customers, attend workshops and conferences and follow people on Twitter. There are tons of things to write about.

Of course the technology is ever-evolving, but the basics don't change. We have the best hardware and the best operating systems. We need to virtualize, we need change control, we need to find ways to keep up to date with the technology around us. Hopefully the links and articles I share help you keep up to speed.

I plan to make a bigger deal of the 10-year anniversary in 2017, but for now, let me just say thank you for reading, one week at a time.

Posted July 12, 2016 | Permalink

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