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Copyright 1998-2022, Southern California OS/2 User Group. ALL RIGHTS RESERVED.

SCOUG, Warp Expo West, and Warpfest are trademarks of the Southern California OS/2 User Group. OS/2, Workplace Shell, and IBM are registered trademarks of International Business Machines Corporation. All other trademarks remain the property of their respective owners.

The Southern California OS/2 User Group
P.O. Box 26904
Santa Ana, CA 92799-6904, USA

July 2003


 Dear Mr. Know-It-All 

Mr. Know-It-All has the answers to even the really tough questions.


Question:

I installed a new disk drive and now CHKDSK traps when attempting to AUTOCHECK after a dirty shutdown. How do I fix this?

Answer:

You did not mention the size of the new disk drive and the partitions, but most likely the drive is large and you created one or more large HPFS volumes or partitions.

Under normal conditions, when the HPFS AUTOCHECK logic invokes CHKDSK at boot time, the kernel is still initializing the system and the virtual memory subsystem is not fully initialized. This limits the amount of memory available to CHKDSK and an attempt to CHKDSK a large partition will fail.

You have several options that will allow CHKDSK to run successfully:

  • Use CHKDSK.SYS.
  • Run CHKDSK with /C option.
  • Use the EARLYMEMINIT kernel option.
  • Use JFS volumes.
These options all have positive and negative features.

Use CHKDSK.SYS

CHKDSK.SYS is base device driver which runs early in the boot process and allocates memory that CHKDSK can use during AUTOCHECK.

To use CHKDSK.SYS add:

  BASEDEV=CHKDSK.SYS
to CONFIG.SYS before any other SYS BASEDEVs.

The downside of using CHKDSK.SYS is that you will be forced to reboot after the AUTOCHECK completes. However, if your setup requires access to files on large partitions to boot correctly, your choices are limited.

Run CHKDSK with the /C option

CHKDSK can be run from CONFIG.SYS. With the /C option, CHKDSK will bypass the full scan unless the drive is marked dirty.

This is a good method for checking large data volumes or partitions that are not otherwise accessed before the PM and the WPS start up.

To use this method, add the line:

  CALL=x:\OS2\CHKDSK.COM y: /F /C
to CONFIG.SYS for each drive to be checked. Replace x: with a reference to your boot drive. Replace y: with a reference to the partition or volume to be checked. Place the CALL statements before any other CALL or RUN statements in CONFIG.SYS.

Use the EARLYMEMINIT kernel option.

The EARLYMEMINIT option changes the kernel behavior so that the virtual memory subsystem is fully initialized before the CHKDSK AUTOCHECK logic runs.

This option does not work on all systems and is considered somewhat experimental. The other options are usually a better choice.

To use the EARLYMEMINIT option, add the statement:

  EARLYMEMINIT=TRUE
to CONFIG.SYS. The placement does not matter.

Use JFS volumes.

The JFS file system, unlike the HPFS file system, does not have problems checking large volumes at boot time. JFS volumes also CHKDSK much faster. JFS also supports much large cache sizes which improves overall performance.

The only real downside of JFS compared to HPFS, for most users, is that the IFS code is young compared to the HPFS code. There were some reports of data loss with early releases of JFS.IFS, but the current releases appear to be as solid as HPFS.IFS.


Curious or in doubt, you can ask Mr. Know-It-All
OS/2 is his specialty and sharing solutions is his passion
Mr. Know-It-All lives in Southern California.


The Southern California OS/2 User Group
P.O. Box 26904
Santa Ana, CA 92799-6904, USA

Copyright 2003 the Southern California OS/2 User Group. ALL RIGHTS RESERVED.

SCOUG, Warp Expo West, and Warpfest are trademarks of the Southern California OS/2 User Group. OS/2, Workplace Shell, and IBM are registered trademarks of International Business Machines Corporation. All other trademarks remain the property of their respective owners.