I think the stalactites indicate G-list sectors that the head has to move to before reading. The read block size affects the graph sharpness, like the bandwidth controls on a spectrum analyzer. In Windows the boot drive will show non-repeating spurious spikes when the OS kernel preempts the drive.
It's typical for a hard drive to slow down considerably toward the end, and a CD or DVD drive to ramp up. DVD-DLs give a peaked-roof graph. jsw
And this is FC-AL. It accepts the SCSI commands (so does IDE, for the most part), but the hardware part of the interface is quite different.
It has only two wires of input, and two of output, both differential. It looks for its address on the data flowing through, and if it is not for it, it lets it flow through to the next drive, for up to 126 drives total in the chain. And it is faster than the fastest SCSI.
Original SCSI was a 50-pin connector, with an 8-bit wide bidirectional data path, and a few handshaking signals, plus a matching ground for each data wire.
Wide SCSI is a 68-pin connector, and 16 data bits, but otherwise pretty much the same. Except that it may also be HVD (High Voltge Differential) or LVD (Low Voltage Differential). The latter can have the plain (single-ended) drives connected and it will work, but it slows down a bit. :-)
Then there is the SCA (Single Connector Access) which has an
80-pin wide connector, which gets the wide SCSI data though some of those pins, the +5V and +12V power, and four wires to specify which SCSI ID the drive will answer to. (It is determined by which socket it is plugged into when there are multiple drives in a housing.) It is a hot-swappable interface, unlike the others. The power pins make last or break first when plugging in or unplugging.
The FC-AL is like the SCA, except that it is only a 40-pin connector, and has seven wires to specify the SCSI address. Also hot-swappable.
O.K. I actually have a Windows 2000 system, and the install media for it. All I need is the right card to allow it to talk to the drives. :-) It's not like I'm using that system for anything else. :-)
Hmm ... At work, I was part of the SysAdmin team, and at home I own all the Sun machines (purchased at hamfest and eBay prices -- certainly not new. :-)
I had already been playing with Sun workstations and servers at home when they started that SysAdmin team. I'm retired now, so it is all my machines (well ... except for the one which my wife uses. :-)
A very good page. Thanks. I did learn things, some of which should have been obvious, but I had not considered them.
Ouch! Linux 10.54, and I'm running 6.6.?, which appears to be the last version to escape for the UltraSPARC 64-bit CPUs. This means that I have to get a PCI interface FC-AL card to talk to the drives with something newer.
But then, I'm not sure that a benchmark program would be much help, anyway.
A graph of read speed is the best free quick test I've found to determine the quality of used hard drives, or sample CDs and DVDs before buying a big spindle. Any problem slows it down; it's like a Check Engine light. I save the initial graphs to check for deterioration later.
Rubtsov's HDD Scan program goes further and records the access time and block number if it's over 50mS. That's good for serious repair such as partitioning around a crash site, but the simpler HDTune type is easier to use otherwise. jsw
The trick is "never switch the output side of a VFD while it is powering a motor. If it is halted, you can swithc over to another motors before spinning it up again. (What you need is an interlock so the VFD has to be at "halt" before you can switch to a new motor.) But two VFDS are nicer, anyway.
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