| Title: | POLYCENTER Console Manager |
| Notice: | Kits, Scans, Docs on CSC32:: as PCM$KITS:,PCM$DOCS:, PCM$SCANS: |
| Moderator: | CSC32::BUTTERWORTH |
| Created: | Thu Aug 06 1992 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 1541 |
| Total number of notes: | 6564 |
I am running PCM V1.1 on VMS V6.1 - 6320 w/128meg
It appears that PCM does one I/O per CHARACTER when logging console
data TO THE SYSTEM DISK. Can this be true?
The log disk for a particular system will max out in I/Os on very
simple things - for instance:
Logged into console of system - do a DIR SYS$SYSTEM:
The disk logging disk saturates with I/O, apparently each and every
character causes an I/O on the disk. The output is VERY slow.
When logging is turned OFF, performance is excellent and no disk
I/O takes place (as expected).
Why does it take so many I/Os to log data to the system disk?
The performance of this thing is REAL BAD when logging to the system
disk.
When logging is to a non-system disk, there is far fewer I/Os and
performance is much better.
Jim Lind
Computer and Network System (CNS)
Colorado Springs
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 254.1 | STREAM_LF File Characteristic | BSS::LIND | Jim Lind; 592-4099 CX03-1/N14 CNMC-West | Wed May 11 1994 08:42 | 13 |
I suspect that the problem with 1 I/O for each character is associated
with files that are created without the STREAM_LF characteristic.
For some reason, log files on the system disk were created in such a
way that each character was a separate record. This can be verified by
typeing the logfile for the node. If there is one character on each
line, you have a problem.
The fix is simple ... delete the three files associated the the problem
node. The next time PCM startes up it will create files in with the
appropriate characteristic.
Jim Lind
| |||||
| 254.2 | LOG FILE I/O | OPG::ENTWISTLE | Thu May 12 1994 12:15 | 12 | |
Sorry about the delay in replying here. It is quite possible that if you have a lightly loaded CM system e.g. half a dozen consoles with sporadic traffic, you will see a lot of log file I/O's per n bytes of data. CM doen't do too much buffering because the event contexts are retrieved from the log files and we like to keep them as current as possible. CM writes log data to the files either when its buffer for a given console is full OR when it has nothing better to do which will be most of the time on a lightly loaded system. CM's I/O in general is rather inefficient when the load is light becoming more efficient as the load increases. Regards, Graeme | |||||