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Published: 10/22/98 - last updated: 4/16/99
As many of you know (and reported in the FAQ) owners of G3 cards other than Newer Technology designs have reported problems completing backups using Dantz's Retrospect software (the industry standard in Mac backup software). I've seen the problem here with several G3 cards (XLR8, PowerLogix and Bottom Line's Railgun). Basically the backup is unable to complete or a verification of files backed up to tape fails (the former is what I've seen). Retrospect shows the backup 'stuck' on one file (it happened here after several hundred MB of files were copied) and the tape drive has stopped running (the activity LED is often still lit on the drive yet no activity is occurring). Note I used Retrospect version 4.0. Version 4.1 is available now (see the links section below for URLs).
Although Retrospect is not locked up (you can abort the backup), the SCSI bus is so hosed at that point that no other SCSI util can operate properly (most sit with a hourglass cursor forever trying to poll the SCSI bus for devices). A restart is needed to reset the SCSI manager. I've found what appears from initial tests to be a solution - actually two solutions - for the problem. These 'fixes' are not supported by Dantz and are only workarounds I have discovered.
As noted in the site news in the past, OS 8.5 seems to contain some SCSI manager changes/fixes (for the Apple G3 onboard SCSI for instance). Initial tests indicate that disabling Virtual Memory under OS 8.5 resulted in Retrospect completing a backup with the XLR8 400MHz G3 CPU Card. Enabling virtual memory resulted in the problem reappearing. Disabling the backside cache was not a solution. I welcome feedback from other G3 CPU Card owners using OS 8.5 with VM off to verify this is a uniform fix.
This one is really unsupported by Dantz and will result in slower backups but so far I've not had problems otherwise. It worked here in OS 8.1 and I suspect earlier versions as well. The two tests (512MB system, G3 CPU card, 3.9GB of files backed up) completed successfully and verified OK. [Worked here for tape drives but Dantz says it will not work for removable disk drives like the ZIP, Jaz, Syjet, etc.] Here's the routine:
Unchecking SCSI Manager 4.3 Mode
Again this method is not endorsed by Dantz, they cannot and will not answer questions related to its use. However this method has allowed me to backup my G3 upgraded Macs where previously I had nothing but failures. Owners of Newer Technology G3 CPU cards do not need to apply these 'fixes' as the cards are fully compatible with SCSI Manager 4.3 mode enabled (the default mode).
Update - Reader Feedback/Tips:
Although some readers say nothing helps, at least two PowerForce G3 owners said booting with no extensions (which disables the backside cache) has helped them complete backups. One PowerForce G3 owner said he'd never had a problem. I've gotten similar comments on the Adaptec SCSI issue, a few owners don't have the problem but the majority do.
Workaround Three I'm not sure about the legality of using Sonnet software with another vendor's card. This is not an endorsement to do so, merely a hope that this information may spur some companies to investigate a software control fix for their own cards.
PowerLogix/Retrospect Fix - from Sonnet?: I've not verified this but it sounds interesting.
" Ok, I never had success with 8.1, and was looking forward to the upgrade. I have the powerlogix 220/110 card running at stock speed (machine crashes went away after I downrated it from its overclocked position), but couldn't backup my two internal hand drives because retrospect always crapped out.
Note that Sonnet's latest Cresendo 1.26 installer claims to add Media 100 PCI compatibility - something that many other G3 cards have had problems with. I guess you can fix some of these issues in software. For more info on the Cresendo 1.26 update see Sonnet's download page. [He later wrote that sometimes the system would still crash/lockup at boot - about 1 in 3 tries he said]
Integer Bus Speeds/Ratios Tip: Gary Schlei reports that with OS 8.5 at last, changing to a integer CPU to Bus speed Ratio (7:1 - not an x.5:1 ratio) solved his problems [his later mail indicated he thought the integer ratio, not integer bus speed was the main factor - but past Apple dev. notes make me think integer bus speeds are recommended as well]:
" I have an 8500 with an XLR8 300mhz card with 1mb backside cache running at 200mhz [This is a PowerForce G3 design card, unlike their 333-400Mhz cards which are their own new design-Mike]He later wrote with additional comments:
Note that with OS 8.1, I still had to apply the "disable SCSI Mgr 4.3" tip noted above with the 400MHz card at 50MHz/8:1 (integer) bus speed/ratio setting. OS 8.5 has changes to the SCSI Mgr and may be one factor (Dantz told me the XLR8 G3/400 card worked fine in O S 8.5 with VM off as noted above). If anyone can verify that integer ratios (x:1 vs x.5:1) and bus speeds (40.00, 41.00, etc.) solve the problem with PowerForce cards and Retrospect backup in OS 8.1 please contact me.
If you can verify that these fixes work for your G3 CPU card
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