klingler@triton.unm.edu (David Klingler) (03/30/91)
Hi, folks. First of all, thanks to Andrew Zimmerman, Patrice Belleville, Tyler Gingrich, Eric Scott, Mark Adler, Scott Bennett, and as always Scott Hess for their quick replies to my help requests on swapfiles and serial port programming. I had asked about modifying my swapfile to make it large enough for my 8 megabyte upgrade (remembering a rule of thumb I'd seen that a swapfile should be about twice the RAM) and programming the NeXT's serial port. For those of you who upgrade your memory and want to change your swapfile to reflect this (and don't know how), modify /etc/swaptab after looking at the man page mach_swapon(8). That's probably something that should be taken care of in future operating system upgrades so that guys like me who are new to unix system management don't have to learn it, and people who buy NeXTs as PC's don't get scared and run screaming out of the house. As far as programming serial ports goes, well, heck. If you're from the PC world and want to program the 8530 directly against everyone's strong advice, or just want higher speeds out of the port, get a Zilog 8530 manual set, read it, and, uh, I don't know the rest yet. I'll tell you when I find out, and maybe by then you'll be done reading the manuals. I've now gone through five optical drives. For those of you who use optical drives, I can tell you this: GET A FILTER! Run, don't walk, to your local NeXT rep or Businessland and ORDER ONE! Sooner or later, no matter how well your drive has been running, it will begin to make reindexing noises and munch a disk. This disk can almost always be recovered (from my experience alone I'd say always), and the drive might work fine after a good cleaning, but now consider the price of a drive out of warranty and how impossibly hard to reach that might be. I bought one of the Businessland fire-sale cubes last November, telling myself that I couldn't buy the equivalent system even using a dread iAPX Taiwanese nastiness (386 or 486 clone) for even near that amount of money, and that I'd program to get my money's worth until my fingers were nubs. Someone at BL in New York took my used cube before it got to me, and I ended up getting one new at the used price. Now comes the tricky part. Between then and now I went through five ODs. I tried steam-cleaning the rugs, building a shelter/hut around the cube and caulking the windows, to no avail. Putting a filter on my drive just about did it, but I put a filter on a drive that had a little dust in it already and after two months it went belly up too. After talking to a NeXT engineer, I found out the following: What my poor local Businessland did not know ---------------------------------------------- Canon is the only optical drive manufacturer that runs cooling air through the mechanical portion of the drive. They have decided not to do this anymore, because doing it bordered on accidental in the first place. NeXT designed a filter for the drive after running into a few people that just could not keep them running. NeXT makes head and disk cleaning kits. They're both worth their weight in gold the first time your drive/disk fails. The head cleaning kit is $60, the disk cleaning kit $15. Get 'em both. If your disk goes down, and you haven't already bought the cleaning kits, do it. Now take the center assembly out of your cube and carefully remove the drive. Do all of this on a nice clean table or work bench with plenty of space, with your shoes off. Touch the kitchen faucet to let loose any extra electrons you've accrued. Clean the drive out thoroughly, using a soft rag, the head cleaning kit and some acetone if you need it. Try not to leave anything, and follow the instructions in the cleaning kits. Remount the drive and put your cube back together after firmly fitting a filter onto the back of the drive. Don't turn your cube back on without a filter. Clean your disk with the disk cleaning kit. Remember to wipe only at a 90 degree angle to the tracks; i.e., from inside to outside. If you clean tangentially to the tracks the servo hardware will have more trouble with any scratches you might add. Be tense, but not too tense. These disks have 70-some megs of error correction in addition to UNIX's duplicate superblocks. You'd really have to mar the disk to make it completely unrecoverable. Try out your drive. I hope it works. I realize that everyone out there with an od might be a little steamed at the thought of dropping an extra hundred bucks on filter and cleaning kits, but consider that one cannot expect any removable media to work indefinitely without cleaning. Concentrate on the $2300 you just saved. My local Businessland has been nothing but courteous and professional through this entire process, even if they didn't know much about the problem. They kept smiling and swapping the whole last few months. I have nothing but respect for these guys. NeXT has been out of this world. I say that only partly because of a recent experience with Mr. Steven Jobs. I won't talk about it but I'm more impressed than ever with the whole company. My computer is the most well-designed piece of equipment I've ever owned except my CDC Wren, and I'm going to do everything I can to make NeXT a success. As I get to know the company who made my computer I feel more and more comfortable recommending it. My optical drive is working now, and I expect it to keep working. As a technician I think it's basically a great piece of equipment that needs a filter to stay that way. Get one and have cheap/reliable storage that becomes doubly invaluable AFTER you add a hard drive. My computer's name is Alice, and I will spend the next decade growing into her. She now has a Maxtor 349 meg hard drive, an eraseable magneto-optical 256 meg drive, 16 megabytes of RAM and the best GUI I've ever used, not to mention some dandy throughput. Great PC, huh? Dave klingler@triton.unm.edu (505) 266-8135 By the way, I guess the world being what it is I should mention that you follow the above instructions completely at your own risk. I just stopped worrying about my _own_ optical drive! Be careful, and take the instructions to a certified NeXT technician if you're the least bit nervous. Good luck!
rca@cs.brown.edu (Ronald C.F. Antony) (03/31/91)
In article <1991Mar30.083055.21766@ariel.unm.edu> klingler@triton.unm.edu (David Klingler) writes: >For those of you who upgrade your memory and want to change your swapfile to >reflect this (and don't know how), modify /etc/swaptab after looking at the >man page mach_swapon(8). As far as I know this is not needed. The swapfile adjusts it's size as needed. Or have there been any changes in 2.0 that escaped me? Ronald ------------------------------------------------------------------------------ "The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man." G.B. Shaw | rca@cs.brown.edu or antony@browncog.bitnet
matthews@lewhoosh.umd.edu (Mike Matthews) (04/01/91)
Regarding the "swapfile should be twice as large as real memory" comment, I have been running a 20M swapfile on a 20M core memory system for a while now, with nary a problem. The only time the swapfile grew (by more than a megabyte) was when one of the programs I got off the net really screwed up virtual memory (one program should not cause the swapfile to grow by 18 megs when nothing is really happening...) If you don't swap much, then you don't really need a huge swapfile. ------ Mike Matthews, matthews@lewhoosh.umd.edu (NeXT)/matthews@umdd (bitnet) ------ "Every time I think I know where it's at, the move it."