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Retrospect Backup Tips for PowerForce/XLR8 G3 CPU Cards
Published: 10/22/98 - last updated: 4/16/99


  • Some Readers report that Powerlogix's beta 'Guardbit' fixes their Retrospect backup problems, others note XLR8's control panel v1.3 works better. Check the software download pages of their sites for the latest versions. Also check the Rate Your G3 Card database for owner feedback. The new FAQ also has more info on G3 Upgrade compatibility info.
  • Note that Dantz tells me that the Disable the SCSI Manager tip noted below will not work for removable drives that mount on the desktop (ZIPs, Jaz, Syjet,etc.) but I've seen it work fine for tape drives.
  • Dantz has posted an official tech note on the Retrospect and G3 CPU card upgrades issue at: They report that Newer Tech, Vimage (with software v1.2 ) and Sonnet (with software v. 1.2.7) passed their tests. The PowerLogix card passed with a beta test version of their new software, which is not available yet. XLR8 owners will want to try the tips noted below. [12/16/98]
  • Integer Bus/CPU Ratios: Gary Schlei wrote that a tip from on using integer CPU to Bus speed ratios from XLR8 solved his Retrospect backup problems in OS 8.5. [11/14/98]
  • Sonnet Cresendo Control Software: See Workaround 3 for a new reader submitted solution (unverified) that using Sonnet's software fixed the problem on his PowerForce G3 card. [11/12/98]


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).

The Problem:

  • Backup never completes. Retrospect shows one file being backed up (forever). SCSI bus is locked in a loop, tape drive may be stopped or running continiously. This usually happened here after several hundred MB of files were copied. (Tape drives seem to be the most problematic - ZIP, Jaz or MO drives may be fine or show compare (verify) errors only).
    = or =
  • Backup completes but verification fails. (I didn't see this failure mode personally - my backups never completed.)

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.

The workarounds below resulted in successful backups that verified OK on two test machines. Without using these tips both these machines were never able to complete a backup successfully due to the CPU card used (non-Newer Tech design). Due to the variations in system configurations, CPU Cards, tape drives, installed software extensions, etc. I cannot guarantee they will work in your specific Mac setup. My test systems were a 9600/350 with 312MB RAM and OS 8.1 and a Genesis with 512MB RAM, dual ATTO SCSI cards, 4 drive Raid and wide Cheetah Boot drive running OS 8.1. Retrospect 4.0 and and XLR8 400 card were used for the tests.
Although rare, I have had readers with PF G3 cards report no problems and for some nothing may help until there is a softare fix. However for those that have had problems they are well worth trying. If you've had problems in the past I welcome your comments after trying these tips. Please note your OS version, CPU Card type (Brand/Speed), Mac model, Retrospect version and backup device used when submitting reports.

Workaround One -Requires OS 8.5:

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.

Workaround Two - For OS 8.1:

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:

  1. Launch Retrospect
  2. Select the "Special" tab
  3. Hold down the option key and press "Preferences"
  4. In the Restrospect General Preferences panel, select "SCSI" in the left hand column and uncheck "Enable SCSI Manager 4.3" (see image below)
  5. Click OK and then exit Retrospect
  6. Restart Retrospect to have the new settings take effect. Backups should now complete successfully

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.

Got 8.5, turned SCSI 4.3 back on, and tried backing up with extensions off. No good - not only did the program quit, but then I got a finder message saying "one of my disks couldn't be used because an error of type -127 had occurred." Worried about disk corruption, I breathed easier after restart returned all normal.

Then I pondered the Macweek article saying that Crescendo cards had a software fix for the G3 timing problem. Sooooo - I downloaded the driver, installed it, and tried retrospect again. - no luck, it crashed again. That was with a full set of extensions, however....

Setting up so that only the Crescendo extension was active (other than the few basic locked ones), and AHA it worked! Twas even fast!
Thought you might like to know. "

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]
I have had nothing but problems with Retospect giving literally hundreds of "Storageset Header Errors" and "Compare Errors" as well as the scsii bus lockup problem after 300-400mb of backup.
When I called XLR8, they said turn off backside cache. This did not help. (even with all inits disabled)
Yesterday I talked to XLR8 again and they said you need to an "integer bus speed ratio"
The recommended settings for this card had a "7.5 Bus Ratio" which produced a 300mhz processor speed at a 40mhz bus speed.
Changing to a "7.0 Bus Ratio" (an integer) produced a 301mhz processor speed at a 43mhz bus speed. ALL PROBLEMS SOLVED.
I ran 3 succuessful Full Backups of 4 different partitions: 900mb, 740mb, 650mb and 490mb.
This was with backside cache running, all my inits (and I have a bunch) and the energy saver control panel set to sleep the monitor after 15 minutes and spin down the hard drive after 30 minutes of inactivity.
BTW this was all done with MacOS 8.5
Good Luck everyone
Gary Schlei "
He later wrote with additional comments:

" Mike,
I always had an integer BUS Speed of 40 and a noninteger ratio of 7.5 as was the recommended setting. Changing the ratio to 7 is what solved the problem. My system worked well with BUS Speeds of 43, 43.6 and 44. (all with a ratio of 7)
I also used a ratio of 6 and was able to achieve a Bus Speed of 50mhz with a 300mhz processor speed. Any higher bus speed and I lost video on my Xclaim 3D video card and 21" Viewsonic PT813 set at 1152x870 at 75hz "

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.

Retrospect Updates:

  • Retrospect 4.1A Updater
    Fixes a problem that occurs when Retrospect is run on an AppleShare IP 6.x Server. This problem can keep users from logging in to the ASIP Server.

  • Retrospect 4.1 Driver Update, Version 1.6
    Updates Retrospect 4.1 to support new CD-RW drives. It also fixes a problem in Retrospect 4.1 which caused faster DAT drives (DDS-2 and DDS-3) on some computers to operate slower than with Retrospect 4.0.

  • Retrospect 4.1 Client Updater
    Correctly updates Retrospect 4.0 Clients to 4.1.

If you can verify that these fixes work for your G3 CPU card
(Vimage owner feedback is especially wanted), please
contact me. Please note your OS version, CPU Card type (Brand/Speed), Mac model, Retrospect version and backup device used when submitting reports.

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