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1 Terabyte DISK Volume for OpenVMS

Edmundo T Rodriguez
Frequent Advisor

1 Terabyte DISK Volume for OpenVMS

Is there a way to use 1 TB disk with
OpenVMS Alpha?

Which firmware, what platform?

I suppose it should be a SCSI disk.
What about SATA disk?
Robert Gezelter
Honored Contributor

Re: 1 Terabyte DISK Volume for OpenVMS


What is (will) the drive be connected to?

- Bob Gezelter, http://www.rlgsc.com
John Gillings
Honored Contributor

Re: 1 Terabyte DISK Volume for OpenVMS


It depends on what you mean. Do you want to take a physical disk drive with a capacity of 1TB or more and connect it to an OpenVMS system? Or, do you want a storage device with capacity over 1TB?

Both are possible depending on the exact hardware you want.

A single >1TB drive would need to be on a storage controller capable of partitioning the drive into chucks smaller than 1TB. OpenVMS would see the drive as multiple volumes, each smaller than the OpenVMS 1TB architectural limit for a single physical volume.

A device larger than 1TB can be created on OpenVMS as a bound volume set (BVS) composed of multiple volumes smaller than 1TB. A BVS may contain up to 256 volumes, so in theory one could create a single disk device of nearly 256TB (but many would question the sanity of anyone contemplating managing such a beast).

I don't think there are any Alpha systems with SATA controllers. Most Alphas have FibreChannel, SCSI or IDE. On older systems you might find CI, DSSI, or a few other more obscure, and now dead technologies.
A crucible of informative mistakes
Edmundo T Rodriguez
Frequent Advisor

Re: 1 Terabyte DISK Volume for OpenVMS

I wanted to take a physical drive of 1 TB and attach it to a Alpha ES47 and or newer architecture like Integrity rx3600 Server.

I suppose the limit you are talking about is on the file system. (Volume per disk)

The idea is that I want to have the less amount of volumes/disk possible for an archive (read only) system.

Naturally the disk will be running in a shadow-set of two at least.
Hein van den Heuvel
Honored Contributor

Re: 1 Terabyte DISK Volume for OpenVMS

Well, as long as the drive presents itself with less than 2**31 sectors it should be fine:

$ x=%x7fffffff
$ shwo symb x
X = 2147483647 Hex = 7FFFFFFF Octal = 17777777777

So if I look at an example "Seagate 1Tb Barracuda ES.2"

The detailed specs give:
Guaranteed Sectors = 1,953,525,168

So that's well under 1024*1024*1024*2

Honored Contributor

Re: 1 Terabyte DISK Volume for OpenVMS

1 TB (marketing) drives should be well within the limits of OpenVMS, as these drives have capacities below the 1 TB (engineering) limit.

Storage marketing uses base 10 for its calculations of storage capacity. Storage engineering uses base 2 for its storage capacity addressing. Why? For the same actual capacity, the marketing values look better (bigger) than the engineering values, and most (non-nerd) humans deal with base 10 better than base 2.

There can be driver issues; there are ECOs listed in the OpenVMS FAQ for some releases and some drivers. (In the same section that discusses the terabyte addressing limit.)

There are SATA controllers around which can and do mimic the IDE/ATA controller driver interface; you might find one that works with DQDRIVER. But you'll slam into the (lack of) 48-bit addressing with this drive. (I prototyped a DQDRIVER variant with the 48-bit addressing changes, but there's no support for that in any shipping driver nor have there been any plans announced from HP.)

Here's a write-up on IDE/ATA addressing:

You might be able to find an UltraSCSI to IDE/ATA adapter; there are a variety of disk adapters available. Now as to whether or not whatever version of the DKDRIVER SCSI driver can deal with this device (or the adapter), that's another matter.

There are a select few Alpha systems with USB support, and USB can deal with terabyte-scale disks.

Try it. Let us know.