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Q:  I have a rev 1 Blue and White G3 - how can I test for data corruption with replacement drives?

A:  (from the 2/26/2001 www.xlr8yourmac.com news page)

Reader Tim Seufert sent his Disk Corruption test utility (click here to download it) mentioned in last week's news. See the readme file for more info on the utility. For those that missed his comments in last Wednesday's news, he noted that although he originally thought his rev 1 B&W G3 with an IBM 75GXP drive was immune to the data corruption issues that IDE chip has with replacement drives, using a tester he wrote discovered otherwise. Here's a repeat of his comments:

" Mike,
Could you update the drive database entry for my Rev1 B&W with a 75GXP to show that I have corruption? I recently wrote a better corruption tester tool and have found that there are very rare read errors (though I've never found a write error).

Small SMI tests will not discover this. It took writing a 2GB test file with multiple readback passes to uncover it (and sometimes it will pass even that test, so multiple test iterations are a good thing).

Also, I'd like to distribute the tester through your site so that xlr8yourmac readers can use it for better corruption testing. It doesn't have a GUI interface because I wrote it to easily compile under either Linux or MacOS, but it should be fairly straightforward to use. You just tell it how many test iterations to run, the size of the test file, and the number of verification passes to do after writing the file, and it goes and does its thing.

Unlike SMI checksum tests, it can detect literally any error (checksums can be fooled). It works by writing a file filled with a (repeatable) pseudorandom sequence. After the file is created, it reads it back and compares the file against the recreated sequence. If any discrepancy is found, it logs it and prints a warning.
Tim Seufert "

This issue has been noted here since about spring 1999 when it was first discovered. Tim sent his tester for mirroring here, so that rev 1 B&W G3 owners can download it for use on their machines. The safest bet for adding/replacing drives on a rev 1 is to use a PCI IDE card. (Although some readers have used the slower CDROM channel and ZIP bay, Apple doesn't recommend the ZIP bay be used for hard drives, due to possible heat issues I assume.)

If you have a B&W G3 and it has the dual drive stacked bracket and dual drive cable, then you have a rev 2 model with the revised IDE controller. There were some interim models shipped without the dual drive bracket however, but with the revised IDE chip according to past reports. To check the IDE chip, see the B&W G3 rev 2 page here which shows where the IDE chip is located and the marking on the revised chip.