Differences between current version and previous revision of SCSI.
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Newer page: | version 8 | Last edited on Sunday, September 11, 2005 9:12:24 am | by AristotlePagaltzis | |
Older page: | version 7 | Last edited on Friday, July 29, 2005 11:41:12 am | by CraigBox | Revert |
@@ -1,20 +1,18 @@
-SCSI is an
[Acronym] for Small Computer Systems Interconnect - a method of attaching peripherals to a computer motherboard. People generally consider SCSI to be more reliable (and more expensive) than [IDE]
.
+An
[Acronym] for __S__mall __C__omputer __S__ystems __I__nterconnect
.
-SCSI allows better throughput
than IDE by allowing commands
to be sent asynchronously - that is, you can send a "read" or "write" request and return immediately, and sometime later (when the device has finished reading or writing) do something with the data. In contrast, for IDE the read request doesn't return until the data has been physically read from the disk
.
+An electrical standard for attaching peripherals to a computer motherboard as well as a communication [Protocol] between devices, generally considered more reliable
than [
IDE]/[ATAPI]. Devices tend
to be palpably more expensive too
.
-The
SCSI protocol requires a host card (called an adapter)
. SCSI peripherals are then attached
to this card
. In theory (ha!) up
to 127 devices in one chain can be attached to each host card
. SCSI cables require a special terminator at each end
.
+[
SCSI] used to be far more sophisticated than [ATAPI]. F
.ex, [
SCSI] pioneered asynchronous command operation -- that is, the host could send a <i>read</i> or <i>write</i> request to a device and go on its merry way, only coming back
to collect the data when the device finished reading or writing
. In contrast, sending a command
to an [IDE] device meant waiting while the data or a success confirmation was being delivered
. Over time, though [ATAPI] (the [IDE] communications protocol) has been becoming ever more [
SCSI]-like
.
-People sometimes describe
SCSI as requiring black magic
(including sacrifricing goat's blood, or occasionally Lusers
).
+The [
SCSI] protocol requires a host card
(called an adapter
). [SCSI] peripherals are then attached to this card. In theory (ha!) up to 127 devices in one chain can be attached to each host card. [SCSI] cables require a special terminator at each end
.
-__Note:__ Do not underestimate the
black majick involved in SCSI! If you don't have
a terminator on the non-controller end, it might work for a while, and then never work again. Or it might work under some OS
's but not others. Put a terminator on it already. While you're at it
, ensure BOTH ends of each channel are terminated. Most modern cards have "Auto" termination, and this almost always works these days, but if unsure, set to "Enabled", terminate the end of the cable, and if you're unsure if your cable terminator is active
or passive, enable "term. power" on at least one of the devices on the channel
.
+People sometimes describe [SCSI] as requiring
black magic (including sacrificing
a goat
's blood
, or occasionally [Luser]s)
.
-The SCSI instruction set for controlling devices is used
in some
non-SCSI places -
for example
, [ATAPI
] uses
a subset
of SCSI commands for [IDE] devices
, and [USB]
"mass-storage
" uses SCSI commands over USB (which is why you need mod_scsi
and scsi_generic support in
the LinuxKernel for usb mass_storage support)
.
+__Note:__ Do not underestimate the black majick involved
in [SCSI]! If you don't have a terminator on the
non-controller end, it might work
for a while
, and then never work again. Or it might work under some
[OS
]s but not others. Put
a terminator on it already. While you're at it, ensure __both__ ends
of each channel are terminated. Most modern cards have "Auto" termination
, and this almost always works these days, but if unsure, set to
"Enabled
", terminate the end of the cable,
and if you're unsure if your cable terminator is active or passive, enable "term. power" on at least one of
the devices on the channel
.
-SCSI over
[IP
] is called
[iSCSI
].
+The [
SCSI] instruction set for controlling devices or a subset thereof is used in some non-[SCSI] places -- for example, the aforementioned [ATAPI], or the "mass-storage"
[USB
] device class (which
is why you need <tt>mod_scsi</tt> and <tt>scsi_generic</tt> support in the LinuxKernel for
[USB
] <tt>mass_storage</tt> support)
.
-!Debian Woody doesn't detect my
SCSI card
-
-Go to http://people.debian.org/~blade/install/preload/ and download the bf24 SCSI driver disc. Modules for the kernel included with Debian's bootfloppy-2.4 kernel are on this disc. It will make the woody install nice and smooth
.
+[
SCSI] over [IP] is called [iSCSI]
.
-----
CategoryStorage