Hidden Value – May 2003

 

Q: I ran checkslt on the MPE/iX 7.5 SLT and it failed. It failed on a DDS2 drive on two different systems but passed when a DDS3 drive was used. The MPE/iX 7.5 SLT is on a 120 meter DDS2 tape. HP, at present, is looking into this. Has anyone experienced this?

 

A: Michael Berkowitz replied:

 

What makes you think you don't have two bad DDS-2 drives. When we had them, we went through them like water, replacing them every couple of months. They are bad news from the word go.

 

After the original poster balked at the idea he could have two bad DDS-2 drives, Gilles Schipper noted:

 

Not surprising at all. I once experienced the following situation. Our customer had a disk crash. Fortunately, it happened just after a full backup. HP replaced the faulty disk drive and we proceeded to perform a system reload from the just-completed backup that had been to a DDS-2 tape drive.

 

As soon as we mounted the tape (on exactly the same tape drive that created it), we received a console message indicating AVR error on ldev 7. I knew right away we had a problem. HP returned to replace the tape drive with another DDS-2 drive. Still no joy. We recommended replacing the drive with a DDS-3 tape drive. As soon as this was done, the reload proceeded without further problems.

 

The bottom line is, as has been mentioned in another post, stay away from DDS-2 drives, as far away as possible. From this experience and others, I have concluded that the dds2 drive is, to put it mildly, flaky.

 

 

Q: This morning I came in to find the backup job stalled. Abortjob was ineffecive, as was abortio. I ended up rebooting the system. While coming up, I got the "defective sector" message with "FILE.GROUP.ACCOUNT has an extent with unreadable data". The file is now locked and I need to use FSCHECK to unlock it.

 

How can I determine which drive this extent is on? I have a good idea which one it  is, but I'd like to be 100% sure before I replace and reload.

 

A: Stan Sieler replied:

 

FSCHECK's "DISPLAYEXTENTS" command may help. Note that, if I recall correctly, it displays logical unit numbers, not exactly LDEVs.

 

 

Q: We were going over our time change procedures and came up with questions about all the different time change methods and parameters and what they mean. For years upon years we have automatically run a job on the time change Sunday at 1:59 AM that basically just changes the time zone. For the last couple of years we have also started running an NTP time synchronization job at 3:00 AM every morning. The TZ variable is set to "PST8PDT". Now as I understand it, NTP is adjusting the UTC time. But does it also adjust the time zone? In other words are we duplicating effort with these jobs?

 

A: John Clogg replied:

 

NTPDATE will not adjust the time zone. It will only accomplish the tiny adjustment to UTC time caused by the drift in your system's hardware clock. There is no problem running both programs the same night, as long as your DST adjustment has completed when you run the NTP adjustment. Since the spring adjustment moves the clock forward, it will happen immediately. The autumn adjustment can take a couple of hours or more, so it calls for greater coordination.

 

 

Q: I have searched the archives and find only a single reference to 'Device Class Limit' from 1996 that listed it at 450. Is that number still valid, and if not, what is the current limit?

 

A: Guy Paul replied:

 

You should be able to find this on Jazz at http://jazz.external.hp.com/papers/limits/os_limits.html

 

 

Q: I'm setting Apache 1.3.4 up for on-line access to reports. I used the fancy indexing feature for the directory index, but when I display the index on a web page, it's truncating the links at about 22 characters. Does anyone know what can be done about this?

 

A: Mark Bixby replied:

 

You want to take a look at the NameWidth option of the IndexOptions directive:

 

http://httpd.apache.org/docs/mod/mod_autoindex.html#indexoptions

 

 

Q: Is a patch required to install disks greater than 9-gigabyte on MPEix 6.0? I am trying to install a Cheetah 36XL, ST336705LW disk. I can format it, but it still shows as UNKNOWN when I do a DSTAT ALL. This disk is to replace the ST39204LW, which was a 9-gigabyte version.

 

A: Scott Swartzell and Craig Lalley replied:

 

It sounds like you haven't added the new disk to a volume set in volutil. If you can see the disk in dstat all, you probably don't need a patch.

 

Stan Sieler added:

 

The maximum size of a disk drive on MPE/iX varies depending upon which release (or patches) of MPE/iX you're using. If I'm in doubt, I check the IODFAULT.PUB.SYS file, and search for "GB" to find what the largest supported disk might be. On our well-patched 6.0 system, I see: '3.50" 73 GB FC Disk Device' which tells me that it had better support a 73 GB disk.

 

By the way, "support" is a slippery concept. For quite some time, MPE/iX hasn't done a proper job of supporting larger disk drives. On 6.0 and later (perhaps earlier, too), MPE/iX would allow you to mount/use a larger disk drive than DISCUTIL (an important offline utility) would support.

 

 

Q: I recently had a problem with an Image B-Tree index. A search like "Z@" (where Z was greater than all present key values) took a long time to come back. Four minutes for the DBFIND! On our test system I tried dropindex/addindex on a restored copy of the database and that seems to have fixed the problem. This index is the built-in IMAGE kind, not Omnidex or Superdex. There were 1.4 million entries in the manual master dataset. So, my question is should we regularly re-index our IMAGE B-Trees?

 

A: Jerry Fochtman replied:

 

This is one of those "it depends" answers. If the dataset is fairly stable without a lot of add/delete, then it could be re-built less frequently than the index for a set that experiences frequent key add/change/delete activity. Keep in mind that KSAM/KSAMXL operates using a 'key' area and a 'data' area. The key area is dynamically maintained as a balanced tree whenever values are added/removed. However, the data portion is a 'first-come, first-serve' approach so its possible that the data for logically adjacent values are spread all over this area causing I/O to be extensive. Especially when doing wild-card qualifications and it becomes necessary for the data entries to be retrieved and evaluated against the request.

 

So the answer is 'Yes", it is a good idea to re-built the indexes periodically. But at what frequency would have to be determined on an individual basis simply because the dynamics of the data and the affect it has on data locality are generally not easily predictable.

 

 

Q: Does anybody know offhand whether the MPE intrinsic FPOINT works on Large Files

(i.e. > 4GB)?

 

A: Gavin Scott replied:

 

Of course it does. FPOINT takes a record number, and Large Files can't have any more records than not-Large files, so there's no issue with FPOINT or any of the rest of the Intrinsics for that matter.

 

 

Q: The following does not appear to be a problem. But for my own edification I would like to now why? We installed a used HASS "Jamaica" A3312A drive enclosure with (2) 9GB FWD SCSI-2 drives. Both drive modules appear to be the same part number "A5238A". I configured both drives in SYSGEN as "ST39236LC" as per instructions from

HP support. However DSTAT ALL shows different IDs. Why?

 

A: John Burke replied:

 

DSTAT is actually reading the ID information off the drive. The difference between SYSGEN and DSTAT does not matter, though many people alter SYSGEN after the fact with the correct ID so it is in sync with reality. In configuring disk drives in SYSGEN, the only thing that really matters is that you get the correct driver. On your system there are only two, one for FW and one for SE. So choosing ANY FW drive would have worked.

 

 

Q: Does anyone know if it's possible to set a var to the result of an finfo across a dsline connection? I want to retrieve the status of a particular file on the remote system.

 

A: Donna Garverick replied:

 

You cannot do it directly. One way of doing it, however, is to create a file equation on the remoted system that includes a 'nodespec' (read 'help all' for file) for the originating system. Then

 

echo ![finfo('myfile','myparm')]>*myfeq

 

That magic file equation will put the information on your originating system. if it's a one-liner file, it's fairly easy to get the input: (input myvar < finfofle). It involves some work, but it's not too bad.

 

 

Q: Any help on the following error on a message file would be appreciated.

 

   +-F-I-L-E---I-N-F-O-R-M-A-T-I-O-N---D-I-S-P-L-A-Y+

   !  ERROR NUMBER: 71    RESIDUE: 8224     (WORDS) !

   !  BLOCK NUMBER: 538976288    NUMREC: 8224       !

   +------------------------------------------------+

 

A: Per Ostberg, Jeff Woods and Stan Sieler all replied:

 

"Too many files open."

 

Stan Siler added:

 

I've seen this a lot with COBOL programs that open a file in utility code that then forgets to close the file. After calling it about 1000 times (more or less), you'll start getting that error.

 

 

Q: I am trying to find information on the Heat Dissipation for a Model 10 disk array, specifically the maximum load BTU's. Where can I find this information?

 

A: Wirt Atmar replied:

 

You don't need to reference an HP site for this information. It's available on the nameplate on the back of your device. BTU's are a unit of work (or energy or heat; the concepts are all equivalent). Kilowatts are a unit of power (work expended per unit time), thus kilowatt-hours (units appropriate for the time integral of power) are equivalent to BTU's.

 

If we presume that all of the electrical energy flowing into an electrical device is dissipated as heat (which is not only a good first-order approximation, it's also the most conservative estimate), then the formula of interest is:

 

     1 kilowatt-hour = 3413 BTU's

 

That is, a 100W (or 100VA) device will emit at maximum 341 BTU's in one hour. HP however is conservative in its estimates of power draws, so the real number will probably lie somewhere between 50 and 70% of such a number calculated off of the nameplate.

 

 

Q: I wanted to know how to check to see if a file name fits the pattern IHOCS###, with ### being three numbers. Is there a pattern matching function to do this?

 

A: John Burke replied:

 

Check out the CI function PMATCH.

 

 

Q: I have a port in HP3000 and I want to know the application that is currently using that port. Is there any command that can show me the applications accessing a particular port?

 

A: Kevin Miller and Jeff Kell replied:

 

:sockinfo.net.sys

 

Enter 'c' for 'call sockets'. Listeners are shown in port order.