[Info-vax] 8.4 freespace-drift problem?

[David Froble]

Stephen Hoffman wrote:
> On 2015-05-22 02:40:45 +0000, David Froble said:
> 
>> Phillip Helbig (undress to reply) wrote:
>>> Twice since the upgrade I've noticed that the free space was off by 
>>> about 4 GB.  (After the upgrade I went from 4-GB to 9-GB disks, which 
>>> gave me 5 GB free instead of 1.  I was really surprised when I saw 
>>> just 1 GB free.)  ANA/DISK/REPAIR fixes it, but it appeared again a 
>>> day later.
>>>
>>> Has anyone else seen this?
>>>
>>> In the last 20 years or so I have never seen this much freespace 
>>> drift on my hobbyist systems.
>>>
>>> The problem (at least so far) has been only on the system disk with 8.4.
> 
> Phillip: Upgrade the entire cluster to V8.4.  You're troubleshooting a 
> fairly long span of software versions in a cluster, you've probably had 
> some hard halts and some crashes, and you're working with a number of 
> badly under-patched V7.3-2 systems.  Your hardware is also not really 
> suited to what you're trying to do, too.   Why upgrade everything?   
> Your V8.4 patches are much newer than much of what you're running on 
> here, and it may well be the V7.3-2 boxes or potentially some quirk of 
> local operations here — crashes and hard halts are the most common 
> causes of free space drift, in my experience — and not the V8.4 box 
> that's centrally causing the drift.
> 
> Phillip: FWIW, you're also running ancient Alpha hardware with what are 
> now exceedingly small disks and probably with equivalently-constrained 
> physical memory, but then this is your museum of Y2K computing, and not 
> mine.  An Alpha emulator will very likely be a substantial storage 
> capacity upgrade, and may well be a memory and performance upgrade from 
> the hardware configuration that you're using here, after all.   Fifteen 
> or twenty year old gear has capacity and performance limits beyond its 
> basic operation, after all.  Emulation at least gets you clear of the 
> pre-EV6 gear you're using.
> 
>> Why am I so happy that I'm still running V8.3 ????
> 
> David: V8.4 with mid- to current-vintage patches works here, and works 
> at the sites I'm dealing with, including with DECwindows on an 
> EV6-compatible graphics controller.  But then I'm not (intentionally) 
> not running a whole lot of 100 MbE hosts and definitely not running HBVS 
> across a 100 MbE network connection — that full copy would take a whole 
> lot longer with the 146 GB disks and the larger disks that are more 
> typical than what Phillip is running.  Multi-host SCSI or FC would be 
> typical for such a configuration, when that's necessary.
> 
> Both: Unfortunately, OpenVMS free space drift has been around for eons, 
> and there's been ongoing work to reduce it.  But it's a cached value, 
> and there are known cases where the value can and will drift.  Hard 
> crashes and hard halts being two of the most common triggers — if some 
> host is working with the disk and is holding the disk lock and performs 
> various deletions which update the free space and then that host 
> suddenly goes bye-bye hard, you will get free space drift.  At least 
> until the next rebuild is performed.
> 
> Phillip: When it is convenient, invoke SET VOLUME /REBUILD=FORCE and the 
> lock value block free space value will be resynchronized with the disk 
> storage.
> 
> 
> 

Ok, I'll admit, some might consider my VMS systems more as heaters than 
computers.  The usage is rather light.

I've got a VAXstation 4000 model 90A running V7.2 with:

Device                  Device           Error    Volume         Free 
Trans Mnt
  Name                   Status           Count     Label        Blocks 
Count Cnt
DFE90A$DKA0:            Mounted              0  VMS072         1257280 
  206   1
DFE90A$DKA100:          Mounted              0  DISK1          3569916 
  119   1


Disk DFE90A$DKA0:, device type DEC DSP3107LS, is online, mounted, 
file-oriented
     device, shareable, error logging is enabled.

Disk DFE90A$DKA100:, device type DEC RZ28M, is online, mounted, 
file-oriented
     device, shareable, error logging is enabled.

Yeah, all that is going to die on me some day, but (cross fingers) today 
is not that day.  Nor is that today's issue.

While VAX doesn't have everything I need, it still can do what it did 
when we all learned to love VMS.  What ever would I do with a 146 GB 
disk drive?

I've also got an AlphaServer 800 running V8.3 with 9 GB and 36 GB disk 
drives.  I doubt I'm using 10% of the disk space.  At this time there is 
nothing that I've asked of the Alpha that it can not do.  I have no 
problems.  Not sure what else I can ask for.

I've got VMS.  I can do program development.  My needs are met.  I'm 
sure my needs do not match those of others.  YMMV ....