DASD or Disk Storage connected to the mainframe and StorWize

When I started this blog, disk storage was a very simple matter. I only considered the storage that was able to connect to the mainframe. I don’t think we even talked much about disk at the time. As you might remember one long time ago post on this blog (Mainframe Talk), real mainframers talk about DASD (dazz-dee) and not about disk. So the list of disk storage was very limited : DS8000 and that's about it.

But things have changed over the years. And our perspective of things has also changed. Mainframe has become more and more open. Look e.g. at the successes of Linux on System z. That’s one passage to, let’s call it, open storage. And in 2010 we had of course the introduction of the zBX, first allowing Power Blades and now Intel Blades with Linux and Windows too. These also need their proper storage. So that's an even clearer passage to open storage. But even our traditional operating systems have found their way to these new storage products.

So, the last couple of years, the scope of storage devices on my radar has broadened. There's e.g. ProtecTier, which was first an open systems solution only, until it introduced the TS7680 ProtecTier Gateway that connected ProtecTier to the mainframe. Next to that we had SVC. XIV followed in line. First it had to be connected via SVC but the "IBM XIV Storage System can now be attached through supported FC switches to z/VM for system use (e.g., paging, spooling, IPL, etc.)". (< IBM VM pages). Yes, you can IPL z/VM from an XIV. And "XIV Storage can also be accessed by z/VM guests through guest-attached FCP subchannels". But it hasn't stopped there. Look e.g. at the announcement of z/VSE 5.1 :

"IBM Storwize V7000 Midrange Disk System :
Storwize V7000 is a midrange disk offering built on IBM System SAN Volume Controller (SVC) technology. It can now be attached through Fibre Channel (FC) switches to z/VSE using Fibre Channel Protocol (FCP) subchannels. z/VSE supports Storwize V7000 (SCSI) devices for system use (IPLable z/VSE system devices) and as data devices. z/VSE is designed to support Storwize V7000 devices in both an LPAR and a z/VM guest environment. z/VSE Storwize V7000 support is available with z/VSE V4.2 and later.

Or take a look at the Supported Hardware list for IBM StorWize V7000 :

"z/VM 5.3.0 and later supports Emulated Device (EDEVICE) attachment for all EDEVICE use including paging, spooling, minidisks, and system IPL.
z/VM 5.3.0 and later also supports guest attachment via dedicated FCP subchannels"

What's my point ? Well, I can no longer pretend to write about high-end storage attached to mainframe. There's a whole range of midrange storage devices that can also connect to this very mainframe and zBX. And with that I'm strangely enough back at my starting point that I only consider storage connected to the mainframe. Only, due to the changing evolution, it's no longer a simple matter because there's much more now. And as I already pointed out before, you have to be aware of what's around, because you will be confronted with situations where people ask you why you choose a DS8800 for your Linux on z environment, rather than e.g. an XIV or a StorWize. And perhaps they're right.

So I intend to also write more about these products in the future. A CIO told me some time ago that because of limited resources people are focused on doing their jobs and don't have any time left to take a step back and have a look at what's new in order to see the greater picture. So, information pointing them in the right direction was always welcome. Well, let me try and help you a bit with this.

And here's my first bit of information. IBM announced today that 'IBM Storwize V7000 introduces new 900 GB SAS drives (ZG12-0038)'. If you're still a completely isolated mainframer or you have been living on another planet the last year and you wonder what StorWize is, I'll come back to that in a later post with a brief introduction to it.