Dan C wrote: >(simplified) The first thing the MacOS does, when accessing a drive, >is read its partition map. Then it loads the full driver (which >Apple stashes in a special partition). Then it accesses the file >system's data (HFS/HFS+ directory structures) from the boot >partition. Then it creates a small file on the boot partition (the >existance of this file is how the system knows it crashed when next >you boot). Then it continues with the boot process. > >If the packets on the SCSI are being corrupted, the read operations >just get repeated until they work (more or less). But the write can >damage things. Murphy's law says it will be the directory write >operation and not the actual file data write that's damaged. :\ > >At that point, the disk is usually repairable if you use Disk First >Aid or another such tool on it. But the longer you wait (the more >writing you do) the worse the problem gets...
I've always run TechTool's defrag and Directory Maintenance at the slightest sign of trouble because I've assumed that system and program troubles compound themselves and by what you've explained, it makes even more sense to nip things in the byte. Thanks for this; it's a keeper. I'm still on the 660 but the 9500 is sitting here running too - I'll file share this info over. >What's the full model number of the Micropolis? Perhaps we can find >you some detailed/better info. Model 3243 - seems to me I saw 3.9 GB on screen at some point; icon title maybe? Here are the two sites that are still leaving me in the dark: http://www.groove-trax.de/jumper/h/txt/2544.txt http://www.thetechpage.com/cgi-bin/db/db.cgi?displayItem=884 What contributes to my confusion is that, of the fourteen pairs of pins, 2 pairs (4 pins) are missing leaving empty holes in the black jumper block. An actual photo would be excellent as these graph-like layouts don't seem to line up, numbers to names not to mention all the mysterious plus' and minus'. There are a couple of other two or four pin groupings elsewhere on the Hd's board as well. >Termination is needed to prevent signals from "echoing" off the end >of the cable. It's the echos overlapping that cause the corruptions. >Sometimes, when cables are short and data rates are slow, such as on >an internal SCSI-1 bus, the echo is minimal so things just hum along >fine. SCSI-2 isn't that tolerant tho... That sounds like the end device in a chain is the only one requiring termination then; isn't that so? Thanks again for expanding my horizons, Terry -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
