lateautocheck - speed up filesystem checks

Release: 0.1

Overview

lateautockeck is an replacement for OS/2's default procedure to check the file systems after an unexpected reboot.
It will significantly speed up the filesystem check of all volumes except for the boot volume. If you are testing hardware or software or if you are a driver programmer, you will probably like this tool. Depending on your hardware and software configuration, the speed up may be up to a factor of 10. It depends on the number of physical disks. The more, the better. Much memory is helpful, too.

Requirements:

• Your CONFIG.SYS must not contain DEVICE, CALL or RUN statements that point to any other drive but the boot drive. By default, this is not an issue.
• You must have at least two partitions. (otherwise lateautocheck is a no-op)
• You need O-REXX or a resent REXXUTIL.DLL version.
  In fact the procedures SysFileSystemType and SysFileDelete are required. They are not part of the Classic REXX documentation. However, they are obviously part of newer REXXUTIL.DLL versions; so it should work with Classic REXX too.
• LVM is recommended. Without LVM the FS checks may take significantly longer than required. (Maybe future versions of this tool will work with FDISK too.)

• Be sure that your CONFIG.SYS does not load drivers other than from the boot drive.
• Be sure to have a set of working boot disks or a boot CD, if something wents wrong.
• Remove the autocheck drive letters except for the letter of your boot drive from the IFS= lines in your CONFIG.SYS.
  They usually look like IFS=HPFS.IFS ... /AUTOCHECK:CDG. You should turn this into IFS=HPFS.IFS ... /AUTOCHECK:D, assuming that D is your boot drive. In the line with IFS=JFS.IFS ... you should remove the autocheck option completely (since your boot drive can't use JFS).
• Copy lateautocheck.cmd somewhere to into your path, e.g. to the \OS2 folder.
• Place the line "CALL lateautocheck" (without quotion marks) in your STARTUP.CMD file in the root directory of your boot drive. If the file does not exists, create it with only this line.
• That's it.

OS/2 REXX executable: Release 0.1

How it works?

Normally, OS/2 checks all file systems on startup automatically if they are dirty. Although, this is a good idea in pricipal, it has several disadvantages:

• A CHKDSK at early boot time is significantly slower than later during boot. (I don't know why. Read cache? More memory?)
• CHKDSK on partitions of different physical disks may run in parallel. Autocheck will not do this.

lateautocheck adresses the above two issues. The only drive that must be checked at early boot is the boot drive itself. The other drives may be checked when the sysem is (mainly) up.

lateautocheck works the following way:

• At first it gets a list of all local drive letters except for the boot drive.
• It will skip drives with the file systems CDFS and UDF.
• It will skip drives where the file system is not dirty.
• It qeries LVM to group the remaining drives by physical disks.
• It will create one job for each physical disk that will check all dirty drives on this disk.
• It will run all the jobs in parallel. They will run in separate windows and wait for a keypress before they close.

Usually CHKDSK jobs on different physical disks will not interfere very much. However, there are some constraints. If you are using IDE drives at the same cable (Master/Slave), only one of the drives can work at once. So a sequencial check is roughly as slow as the parallel check of lateautocheck. SCSI or S-ATA drives are not affected by this performance impact.

Original homepage: http://www.maazl.de/project/misc/lateautocheck.html (not online so far!)