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The Book of SCSI, 2nd Edition
What's Good? For those in a hurry, Appendix A (The All-Platform Technical Reference) is the entire book in a nutshell. I think Appendix A should be included with every SCSI card sold. It includes pin-out descriptions of the major and not-so-major SCSI interfaces, tables for bus timings, and a quick description of termination rules. The pages that surround Appendix A are also quite good.
The chapter on connecting devices to a PC talks at length about one of the more troubling aspects of SCSI; termination. Anyone who has had to troubleshoot SCSI installation problems will enjoy how thorough Chapter 6 deals with troubleshooting. (It even includes what a SCSI signal should look like on an oscilloscope). Programmers will find a Chapter with information on programming using ASPI, as well as protocol specifications for those looking for more low-level information. You'd be very hard pressed to find a more complete and readable treatment of the SCSI protocol than this book.
What's Bad? Unfortunately completeness can lead to information overload. Novice users will find themselves at a disadvantage with the sheer amount of material presented.
When discussing how to set up a SCSI adapter, the book mentions the various PC busses from the earliest IBM PC to draft revisions of PCI and everything in-between. Had I been a novice reader, I would have been overwhelmed with all the information about historical PC busses that are no longer in use. (When was the last time you used VLB or EISA?) In the interest of completeness, the authors also include a chart comparing these interfaces. I question whether this is really necessary. Some may also be put off by the hand-drawn diagrams in the earlier chapters.
On the CD
The CD includes items such as the SCSI FAQ, ASPI Development Files, ASPI tar, SCSI disk driver source for MSDOS, Western Digital SCSI Utilities, SCSITool, Postmark I/O benchmark source code, and Linux SCSI information. Of note, the CD also includes a PDF file of the entire book.
What's in it for me?
The Book of SCSI is definitely written by SCSI enthusiasts. On the early pages, the authors include a bit of SCSI poetry, and the CD includes a text file entitled "SCSI: A Game With Many Rules and No Rulebook?". This book reads with an excitement only an enthusiast can project. If you have ever been curious about SCSI, I encourage you to sit down and read the first few chapters of this book. If you are in a position to use SCSI components more than occasionally, I recommend you purchase this book and keep it on your reference shelf for those times when troubleshooting is necessary.
My biggest complaint? I wish the authors had written this book ten years ago. However, it is still a welcome addition to my library today.
- Chapter Listing
- Chapter 1: Welcome to SCSI
- Chapter 1.5: A Cornucopia of SCSI Devices
- Chapter 2: A Look at SCSI-3
- Chapter 3: SCSI Anatomy
- Chapter 4: Adding SCSI to Your PC
- Chapter 5: How to Connect Your SCSI Hardware
- Chapter 6: Troubleshooting Your SCSI Installation
- Chapter 7: How the Bus Works
- Chapter 8: Understanding Device Drivers
- Chapter 9: Performance Tuning Your SCSI Subsystem
- Chapter 10: RAID: redundant Array of Independent Disks
- Chapter 11: A Profile of ASPI Programming
- Chapter 12: The Future of SCSI and Storage in General
- Appendix A: All-Platform Technical Reference
- Appendix B: PC Technical Reference
- Appendix C: A Look at SCSI Test Equipment
- Appendix D: ATA/IDE versus SCSI
- Appendix E: A Small ASPI Demo Application
- Glossary
- Index
You can purchase this book at Fatbrain.
Which chapter has the instructions for sacrificing the goat?
Funny, I've always heard it pronounced "scuzzy". =P
Perhaps there are even more ways? Feel free to reply with weird pronunciations you've heard.
-Kasreyn
Kasreyn: Cheerfully playing the part of Devil's Advocate to hairtrigger
What's so difficult about termination anyway? Terminate both ends of the bus, nothing else. If you have both internal and external devices, check if your controlles uses the same or separate buses for them. That seems to be it to me..
Yes they are. And this anoys me greatly. Is it really that SCSI parts are twice as expensive to manufacture? I doubt it. Its more likely that they want to keep a large prices difference between them so they can justify SCSI=better. Which it is.
IDE is clumsy and slow compared to SCSI when you start to get many devices in the same machine.
I have a 3-channel LVD SCSI controller in my video system and it's talking to devices of all vintages:
1) Three 18.2GB Barracuda LVD drives in a RAID-0.
2) Four 9.1GB Micropolis UW drives in a RAID-0.
3) 8x CD-R (not CD-RW) drive.
4) Brand new DVD-R drive (whoopee!)
5) Two 1.3GB 5.25" Magneto-Optical drives.
6) 7/14GB 8mm tape drive.
7) 12/24GB 4mm tape drive.
8) Very old (but needed) Archive 2150S (QIC-150).
9) 100 MB Zip drive.
10) 300 DPI scanner (for rough stuff).
11) 1200 DPI scanner (for more important stuff).
The system lives in a server case with dual 450W power supplies, so of these devices, only the two optical drives and the two scanners are external. There are only three cables inside the case for the lot. Theoretically, there are 28 more SCSI IDs available for use.
Now, the nice thing about this is that I can have damn near all of them running at the same time without any appreciable slowdown -- something that never happens on my "play" system with IDE drives.
On my IDE system, I've got two hard drives, a CD-RW and an IDE tape, and the IDE channels often seem to slow each other down and fight for control when I start to burn, backup, and do lots of disk I/O at the same time. I've been told that this is because a single IDE interface doesn't do concurrent access to both drives.
Either way, I love using the SCSI system. It's an I/O monster. And I love being able to just hang whatever kind of device I need to use off of the external connector and know with reasonable certainty that Linux will support it. Long live SCSI.
STOP . AMERICA . NOW
..you're behind the times. Fiberchannel, firewire, and yes, IDE, have made SCSI obsolete. IDE made SCSI obsolete? Heresy! So I would have said myself only a couple of years ago, but today the cost/benefit ratio puts me firmly behind IDE for anything on the low end... and on the high end, let's give SCSI a well deserved retirement, with fanfare and honors, and replace it with more modern stuff, please.
On the low end, the cost difference between IDE and SCSI has been increasing (i.e. prices for IDE drop faster than SCSI) and IDE has also been getting better, to the point where the benefits of SCSI simply aren't enough anymore. IDE drives have gotten smarter, too, making up for some of the performance and reliability differences. If you want a high-performance, cost-effective, "low-end" RAID solution, look to i.e. 3Ware which makes some absolutely superb RAID cards for IDE drives... even though it needs an IDE controller dedicated to each drive it's still cheaper than a comparable SCSI solution, even before factoring in the cost of the drives! And performs at least as well.
As to the high end... Fiberchannel is a step forward, but not enough. Forget all these special purpose buses anyway... my suggestion would be to put a gigabit ethernet interface and an IP stack directly in the drive. In fact, I hear that people are doing exactly that and using something called "SCSI over IP", which sounds like an interesting idea but probably not optimal. Better to run something like GFS directly on the drive.
In other words, my objection to SCSI is: not enough brains per drive! On the low end this can be accomplished with fewer drives per brain... instead of huge RAID arrays with one smart control node (like NetApps, etc), use lots of PCs with small IDE RAIDs... call it RAIIS (redundant array of independent inexpensive servers) if you will. Fewer drives per brain means more brains per drive. On the high end take this to its logical extreme... one drive per brain, a full computer in each drive, each drive a full node on the network.
Either way SCSI is not the answer.
-j
Paying $200 for 34gb of storage isn't whant I would consider reasonable. Especially considering I can buy an IDE drive, with similar performance features and twice the storage space, for $150.
I find it extremely annoying that varying types
of SCSI terminators with the same number of pins
are not labeled by the OEM as HVD, LVD, etc...
I have a zillion terminators here for normal SCSI
devices and a few HVD for my tape libraries and
it's impossible to determine (to my knowledge)
which is which... ugh
A year spent in artificial intelligence is enough to make one believe in God.
Yep, so do I. I have a 486 at home with VLB, and a few at work. Hmmm...a gateway running Linux, a couple of Samba PCs for printer sharing as well.
I also have a server with an EISA bus supporting 4 slots.
--
"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
The reviewer comments that there may actually be too much information in the book, and that newcomers to the subject of SCSI may get lost. My response is that the book itself was never really written for beginners; It was written, IMO, as a technical reference for folks who are in the range between decently hardware-literate (able to build a system without too much trouble) and engineering technician. Witness the oscilloscope examples. How many would-be SCSI users in the Joe/Jane Consumer arena have even seen an O-scope, let alone could guess how to use one or what they're useful for?
Speaking as a second-year EE student, and as someone who's spent 20+ years doing hands-on with all kinds of electronics, the book came as a very welcome reference for me. I would not, however, recommend it for someone who just wants to find out enough about SCSI just to make use of it. For that, I would suggest http://www.scsifaq.org
I would suggest to the reviewer to place a book in context before writing said review. It just plain looks better in print.
Bruce Lane, KC7GR,
Blue Feather Technologies
Basically, take 2 computers with a scsi card in each, and use a scsi cable to connect the two machines. I don't know how this solution compares to myrinet or gigabit ethernet in terms of performance, but the idea is a nice one.
"Hasta la victoria siempre!" El Comandante
if you will notice that most of the more recent
SCSI devices have gone to the LVD technology...
this is due to the fact that every time a faster
SCSI standard emerged, the max cable length was
reduced to a fraction of the previous standard.
LVD and HVD were introduced to combat this problem
while maintaining speed. I'm not sure about the
max cable length of LVD, but HVD is at least 25
meters max length, which makes it more than sufficient for
future desktop devices should cable lengths start
to again shrink with future speed increases...
A year spent in artificial intelligence is enough to make one believe in God.
I'll bet that there's still quite a few EISA systems alive and kicking out there (maybe hidden behind some drywall :-) ).
I had one on the home network up until just last month. It was, alas, decommissioned it after ten years of service and replaced with a PIII/733. Originally, purchased with an Adaptec 1740 adapter (later switched to a 2740) and 420MB of disk space (later up to 12GB) to run Coherent and SVR4.2, it ran various flavors of Linux (mostly Slackware and RedHat) beginning in 1996. If it weren't for what appeared to be problems developing with the memory (hard to find that old stuff) it'd probably still be performing some useful function on the home network. (I haven't tossed it yet so there's still that possibility.)
Cheers...
CUR ALLOC 20195.....5804M
Well, common sense will tell you that if you only need 1 or 2 HDD's and 1 or 2 CD/DVD's then IDE is the way to go if you are the least little bit concerned about price. You get something like 90% of the speed and 90% the reliability in a machine that will serve you well and cost possibly thousands less than a SCSI setup.
Even if you need another 9.9% reliability, IDE raids are becoming more and more commong.
Now, if you're doing 'mission critical' stuff (I hate that term.) you'll know that you'll get that extra reliance and speed, but you'll pay through the ass for it.
Price versus quality, folks.
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
The concept of needing a 400 page book for end users of SCSI devices is appalling.
I bought this book about a year ago, & also read it cover-to-cover. It is good in explaining the hardware issues with SCSI, but it hads a major oversight.
When it talked about Operating Systems, & SCSI programming, it was extremely Wintel centric.
The point of my criticism is not that Fields, et alia, devoted room to getting SCSI to work with Windows 95, NT & 2000, but that they kept in a number of pages from the first edition that talked about SCSI & DOS. (Who is going to lay out several hundred dollars in hardware then run an antiquated OS with it?) This wouldn't be so irritating if it weren't for how little some space they devoted to UNIX-like systems -- less than five pages in total, which amounted to saying ``there are issues, & learn what they are by talking to your OS vendor."
The authors devoted an entire chapter to writing SCSI drivers under Windows using one vendor's SDK, but failed to even mention that one could study how to code for UNIX by looking at *BSD or Linux code -- that was available for study to all.
And as pathetic as the UNIX coverage was, Mac SCSI users received only a pair of by-the-way mentions in the text. And the hardware discussions focussed on common, Intel-based systems; for instance, there is no mention of the Mac 25-pin SCSI cable. Perhaps a beginning SysAdmin could use Appendix A to troubleshoot her/his Sparc, PowerPC, or Alpha systems, but I would recommend Evi Nemeth, et alia _Unix System Administration Handbook_ as the first reference to turn to. Nemeth's book discusses much of the same hardware issues in less space, & in a far more hardware-agnostic manner.
And the material on the CD, although Linux-oreinted, is out of date -- as a simple ``ls -l" will show.
There are strengths in this book, but the weaknesses in it bothered me far more. I hope in the next edition much of the DOS-related stuff is flushed out, & far more useful UNIX-related information is included. And that would make it a definite buy for any computer nerd's library, instead of a strong maybe.
Geoff
I think I see a trend here. Maybe for them it really would be easier to muzzle the entire internet than to produce p
Buslogic made one (the 445 VLB). I have one in my closet gathering dust if you need it. :)
I use my IBM Model 8595 PS/2 for many things including Firewall, HTTP Proxy, NFS & Samba, DNS, VPN, DHCP, SMTP & IMAP, SSH, etc. It has ~27 GB of SCSI disks inside and outside of the frame. Not bad for a 486-50 with 64MB RAM.
-- Remember: Wherever you go, there you are!
Wow, it sounds like you actually have a use for all that stuff. It sounds strange to me to have it all on one system. It seems like keeping it all working would take a significat amount of your time. It also leasves you with one point of failure for all those different tasks. Maybe in your case this all makes sense.
The drives could (admittedly) be replaced by a newer drive configuration (I have a pair of 75GB SCSI waiting to replace all), but I keep putting it off and depending on my DAT24 backups because the move will be a pain and will shut me down (by completely occupying my attention and waiting for everything to copy) for a day or two while I make the switch.
I can imagine that if I got all that equipmet working well together, I wouldn't want to play with it any more than I had to either. If it works, don't screw with it is a good rule to live by in many cases. If you decide you don't need those 75 GB SCSI drives sitting around taking up space, let me know.