[Simh] VAX Tape Emulation?

[Larry Baker]

Zane,

> On Feb 20, 2018, at 7:58 PM, simh-request at trailing-edge.com wrote:
> 
> Date: Tue, 20 Feb 2018 19:58:31 -0800
> From: Zane Healy <healyzh at avanthar.com <mailto:healyzh at avanthar.com>>
> To: Mark Pizzolato <Mark at infocomm.com <mailto:Mark at infocomm.com>>
> Cc: simh <simh at trailing-edge.com <mailto:simh at trailing-edge.com>>
> Subject: Re: [Simh] VAX Tape Emulation?
> Message-ID: <121AEE2A-10DA-4FFE-8028-59B65B6EDDAA at avanthar.com <mailto:121AEE2A-10DA-4FFE-8028-59B65B6EDDAA at avanthar.com>>
> Content-Type: text/plain; charset=utf-8
> 
> 
>> On Feb 20, 2018, at 1:58 PM, Mark Pizzolato <Mark at infocomm.com <mailto:Mark at infocomm.com>> wrote:
>> 
>> I would actually attribute the 'improved' behavior to the fact that tape I/O to TQ 
>> and XQ devices is asynchronous in the latest code.
>> 
>> I would seriously consider Mr Baker's suggestion of backing up to simh disks.  Not to save sets, but to merely using VMS backup to perform BACKUP/Image to RQ units attached to disk container files.  Thus allowing any recovery you might need to have random access to the original file system without having to dig through a save set sequentially.
>> 
>> An industrious fellow might also want to manage the RQ media setup and change activities automatically from the AXP system with a program that does a TCP connect to a simh Remote Console.
>> 
>> - Mark
> 
> Based on the documentation, the TQ device appears to be limited to 2000GB.  As a result I’ve been using the TS device.
> 
> Realistically, once I get these “tapes” created, I’ll be migrating part of the data from physical disks on the Alpha, to disks on SIMH/VAX.  I’ve already done some experimentation with that.  Unfortunately I have ODS-5 data, and some software requires an Alpha.

> ...

> End Result, I think I’m going to have to resort to the disk solution.
> 
> Zane


You should be able to write an ODS-5 backup save set to an ODS-2 disk image on your SIMH VAX.  It may help you decide whether the cluster I/O or the virtual tape drive is the culprit crashing your VAX.  Make the VAX disk large enough.  Cluster mount it.  Do the backup entirely from the Alpha using MSCP I/O.

One thing I've never tried is to restore ODS-5 files to an ODS-2 disk.  Does BACKUP give you some options to at least deal with renaming non-ODS-2 file names?

Larry Baker
US Geological Survey
650-329-5608
baker at usgs.gov

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.trailing-edge.com/pipermail/simh/attachments/20180220/870bae3f/attachment.html>