Date: Thu, 4 Dec 2003 12:20:44 -0800 From: John Niven <[EMAIL PROTECTED]>
This is a good point. Somebody told me the NuBus bus only could do 10Mb/s. When I get the stripe mounted and running I'm only getting 4~5 MB/s. So I wasn't expecting much. This was more about RAID/SCSI hands-on education :-)
NuBus runs at 10 MHz. However, it is 4 bytes wide (32 bits) so the theoretical maximum transfer over NuBus is 40 MB/s or 320 Mb/s. However, because of transaction overhead and such you can't expect to actually see that performance.
If your NuBus card's firmware uses block transfers (transfers several cycles of data for a single address cycle) then you can get pretty close to 40 MB/s in theory, but still probably not closer than 7/8.
FWB was a good company in the distant past, so I expect that the JackHammer does use/support block transfers.
A single drive of a more modern vintage could supply close to the 20 MB/s potential of the JackHammer. But, that might cost money of course...
Originally I had visions of doing more than 2 drives in one of the more secure RAID schemes. I liked the idea of having some secure storage available on my home network. I've just got hung up making the basics work. Also FWB HDTK can only do RAID 0 or RAID 1 :-( Got any other s/w suggestions?
I am not aware of any RAID solutions beyond level 0 and 1 for Macintosh NuBus systems. There was probably something, somewhere, which was rare and expensive, but it certainly wasn't common and probably wasn't a software solution.
However, for data security on a NuBus system, I would probably pick up a few modern wide SCSI drives which will deliver 20 MB/s of real world performance (this is very different from the advertised interface transfer rates) and RAID them in a level 1 (mirrored) RAID. Each drive will max out the JackHammer during transfers and while writes would probably be at half speed (~10 MB/s because you're writing to two drives) most of the RAID level 1 software will interleave the reads so that you should get close to 20 MB/s on reads.
Another trick is to get something like a Quadra 900 or 950 and install two JackHammers and spread the drives across the JackHammers. However, Kaye Yum tried this and found that performance was not improved. He may have been using SoftRAID though. I'm not sure if anyone's tried it with an older version of RAID ToolKit. SoftRAID is relatively recent so it may not have optimized NuBus transfers the way it does on PCI systems.
Jeff Walther
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