Devices in Solaris

This Wiki is brought to you by Backup Central, where you can find the Mr. Backup Blog, Forums, and a mailing list for each forum!
Backup FAQs	Service Providers	Backup Software	Backup Hardware	Backup Book Wiki	Free Stuff	Miscellaneous

A. ``A Networker User" and Dana Bourgeois discussed this on 5 Feb 1999:

Solaris device names: ?lbn = low density ?mbn = medium density ?hbn = high density ?cbn = compressed ?ubn = exactly the same as compressed (I think the u means ultra)

The densities correspond to the settings in st.conf, and by default your st.conf file is probably wrong, i.e. not configured. Check the archive for lots of good info on st.conf settings for your particular devices.

This is true. You need to set up your device type in the st.conf file and how you set it up will determine how many different densities and options are available. If you only set up one entry for DLT, for example, then you can expect that either the above device types will either not work or they will all work the same. To get differences among the l, m, h, c, and u devices, you would need to have different entries for all of them.

You almost certainly want to be using ?cbn on devices which support compression. Except for that hardware which compresses by default or has device-switchable compression. My AIT drives are configurable for compression from the jukebox front panel. I have it ON and want it always compressing so I really don't care about the ?cbn device entry. I will always use hardware compression and the server doesn't know and can't tell.

(The "b" bit means Berkeley style devices, you should use these with NetWorker.)

Yes. True.

The 'n' represents a 'no-rewind' device. This means that the tape is not rewound at the end of the write stream. This is important. Legato needs to have control over the location of the tape in the drive. You don't want the drive moving the tape except under command from Legato. Without the 'n', a lot of hardware will rewind the tape back to the beginning when writing is finished. Hoo Boy! Would that (eventually) cause a lot consternation to Legato! I think it asks for a tape reposition at the end of every write stream (which would succeed) but then the drive would rewind back to the beginning. At the next saveset,

Legato would assume proper positioning and just start writing...over the tape label and all of the previous chunks. I think you'd be able to get an awful lot of data on that one tape if one session didn't completely fill it up and go to the next tape. Like an infinite amount?

Tape drive configurations are kept at /kernel/drv/st.conf (for Solaris). The format for this file is documented in the ``st" man page, while further details can be found in the ``mtio" man page as well as in the file /usr/include/sys/mtio.h.

Legato has sample entries for versions of Solaris from 2.3 thru 2.5.1 at: ftp://ftp.legato.com/pub/NetWorker/Unix/Solaris