Operating System - OpenVMS

device naming convention - HELP

Regular Advisor

device naming convention - HELP

I cannot find any specific documention on naming standards for disks. There is a blurb in the install and upgrade manual.

How are the devices named? Why are some DKA and other DUA... is there a table or matrix I can reference?

Esteemed Contributor

Re: device naming convention - HELP


Check out the following link:


Thanks & regards,
What would you do with your life if you knew you could not fail?
Honored Contributor

Re: device naming convention - HELP

While I think there is a doc about that very subject, is there something you try to solve ?

You can have dia (DSSI, or SCSI-1 if you prefer), dra (raid), dsa (shadowing), you can have an alloclass ($1$, ou $255$, or...) prefixing the disk name...
Jan van den Ende
Honored Contributor

Re: device naming convention - HELP


Well, disk-names (at least the physical system-given names) follow a rather rigid standard:
First letter: type, D=Disk, T=Terminal, M=Magtape or Mailbox, etc,
Second letter: driver ID; K=SCSI, U=DSA-compliant, I=special DSA-compliant DSSI, S=Shadow, G=SAN, R= Maybe very old, RP-typt device, OR, local-raid controller
Third letter; controller designation (in the order detected by hardware)
A=first controller, B=second, etc, (especially DSSI & SCSI can get quite high up); pseudo-controllers & indirect controllers (shadow, SAN), always use A.
Here it gets more complicated, various controllers have their own conventions. Sometimes can be set by software, sometimes by switches, sometimes defined by slotnumber, ....
See their documentation.

The only REAL sensible thing to do is USE VMS flexibility: DEFINE a LOGICAL NAME for any disk EARLY in the bootstrap (ie, in SYLOGICALS.COM), and ENFORCE using ONLY these.

... and in a development environment, I made it customary, way back when, to somehow swap those meanings every once in a while, and any developer that used hard-coded device references was educated the hard way by that.
It HAS lead to lively debates sometimes, but more important, it lead to software that could easily be transfered to other systems.



Don't rust yours pelled jacker to fine doll missed aches.
Honored Contributor

Re: device naming convention - HELP

Adding to Jan post:
Second letter "V" are floppy disk, "Q", IDE disk.

Antonio Vigliotti
Antonio Maria Vigliotti
John Gillings
Honored Contributor

Re: device naming convention - HELP

Generalising a bit, this is really just a subset of the device naming standard. You can find the naming scheme described in "OpenVMS User's Manual" "12.6.4 Using OpenVMS Cluster Device Names". Device names are in the form "ddcu" where "dd" is the device prefix, "c" is the controller letter and "u" is the unit number.

To the specific question "Why are some DKA and other DUA" the "DK" and "DU" are device name prefixes, registered for specific device drivers. "A" is the controller letter. The first controller found is "A", the second "B", then "C" etc... The unit number is an integer starting at 0, with an upper bound depending on the device driver.

The assignment of device driver prefixes is a moving target as there are many supported device types. You can find some tables (at least for VAX) in "OpenVMS System Management Utilities Reference Manual", "Table 19-1 Device Type Codes" and "Table K-1 SYSGEN Device Table (VAX Only)"

Ordinarily a system manager doesn't really need to be concerned about the name as it will be determined automatically, so OpenVMS doesn't attempt to publish a complete list.
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