OpenVMS on an EVA

[Karen Lee_3]

We are considering moving our existing 2.5Tb of data to an EVA. If we do, what is the largest /maximum_files I can use - Openvms Alpha 7.3-1?

[Hein van den Heuvel]

[wrong forum group!]

The answer is: 2^24-2^16-1 = 16711679
The VMS on disk structure uses a 24-bit file ID.
(+ 16 bit sequence number + 8 bit volum id)

See recent topic:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=975346

To find this and related topics google for:
+site:itrc.hp.com +openvms +maximum +files


hth,

Hein.

[David Jones_21]

maximum_files isn't the only limit your migration has to deal with, you are limited to 1 terabyte per volume as well. I think multiple 1 TB disks bound into a volume set should accommodate you provided no single file is larger than 1 TB.

[Ian Miller.]

The volume limit is 1Tb. You can't bind multiple volumes together to exceed this.

and the inevitable FAQ reference :-)
http://h71000.www7.hp.com/faq/vmsfaq_013.html#file5

[Jan van den Ende]

Karen,

for completeness:

- the answer by Hein is the max # files PER VOLUME
- David & Ian gave the 1 TB / Volume
- Multiply that by 1023 Volumes / EVA

--- and if you are REALLY hungry, you can attach multiple EVAs.

Proost.

Have one on me.

jpe

[John Travell]

Ian,
> The volume limit is 1Tb.
> You can't bind multiple volumes together to exceed this.

That's not what Andy Goldstein said at the London TUD in October 2004.

> and the inevitable FAQ reference :-)
> http://h71000.www7.hp.com/faq/vmsfaq_013.html#file5
there is nothing in the FAQ that says you cannot bind together 1Tb volumes.
Do not forget the RVN in the file ID.
JT:

[Ian Miller.]

Andy G would know the definitive answer.

[Robert Gezelter]

Karen,

Also, if you upgrade to 7.3-2 or 8.2, you can utilize the dynamic volume support to perform future volume reconfigurations online without interrupting user activity.

I presented a session on using these features at the recent HP Tech Forum. The notes can be found at http://www.rlgsc.com/hptechnologyforum/2005/1146.html

- Bob Gezelter, http://www.rlgsc.com

[John Gillings]

Karen,

The current limit for a "disk device" on OpenVMS is a bound volume set of 255 x 1TB disk volumes. Should be enough for anyone Eh? ;-)

That would be a seriously nasty chunk of storage to manage. Just mounting it needs extended DCL (not available on V7.3-1), or a purpose built program calling SYS$MOUNT. BACKUP would be a nightmare, but a mere triviality compared to what you'd have to do to restore that sucker!

Bound volume sets are evil. They should be avoided if at all possible. However, if you need a single file larger than 1TB, you don't have a choice.

If your 2.5TB of data are in smaller files, and you want them to appear to be on a single disk, I'd recommend distributing them across multiple < 1TB volumes and use a search list to reference them.

Best bet would probably be do just replicate the devices you already have. I'd STRONGLY recommend V7.3-2 minimum (completely transparent to your application, don't let anyone tell you any different). You can then INITIALIZE all your devices with /LIMIT to make them dynamically expandable. If you then mount everything as host based shadow sets, future migrations of disk storage can be done live. ZERO down time, all data moved while applications are running.

[Uwe Zessin]

> Should be enough for anyone Eh? ;-)

"I think there is a world market for about five computers".

"Nobody will ever need more than 640k RAM!"


Just yesterday I was talking with a colleague about one special marketing person (whose name escapes me at the moment) who worked for DEC here in Germany. It was in the late 1980s, he was talking about endless CPU power and GigaBytes of memory, graphics and so on. We all were laughing about his presentations, because they did sound too spetacular. Our largest systems, 2x VAX-8650 had about 16 MegaBytes of memory!

Today, my iPAQ has 64 MB, a 1GB SD Memory card and my Notebook has 1.25 GB memory.