Blizzard PPC scsi transfer speeds

[Boot_WB]

Hello,

I have BPPC/040/240 with scsi, and have been tweaking the settings to try to get the max transfer rate I can out of my Seagate 8.4GB UW hard drives (ST39173LC).  They're capable of differential 16-bit trnsfers, but have jumper set to force single ended, and automatically fall back to 8-bit transfer modes.
Termination is correct - I have created a 68-50 pin cable adapter for the blizzard ppc, so that a 68-pin cable attaches to the 50 pin HD connector on the PPC as shown here:

1  BPPCscsi provides low-byte termination
2  first position has a 68-50 pin adapter providing high-byte termination.
3  Next 2 positions have the 2 68-pin drives (set to single-ended mode)
4  Last position has a 68-pin active terminator on the end of the chain.

Thus both high-bytes are terminated around the hard drives (to keep them happy) and low-bytes are terminated at the Blizzard and at the end of the chain.  
I get no scsi errors, lockups, etc.

SCSIspeed reports that with 256Kb buffer, in Sync mode with 3-handshake bits I get ~8MB/s transfer speeds.  Not quite 10MB/s, but I am happy with that.

When I actually transfer a single large file (say 30MB) I get:

Hard-drive to memory = ~2MB/s
Memory to Hard-drive = ~1.8MB/s
Partition - Partition = ~1.8MB/s

I am currently using SFS, however the results were about the same with PFS3.

Mask        = 0xFFFFFFFF
MaxT        = 0x7FFFFFFF
Block size  = 1024
Buffers     = 256

(Buffer size = (Buffers * Block size) = 256Kb

Also, my TEAC scsi CD/rw doesn't perform as well as I'd expect - transfer speeds according to SCSIspeed are - at best - around 2.2MB/s.  The drive is capable of 32X speeds (around 4.8MB/s) - what gives?  I'm using CacheCDFS, since the Blizzard CD munting tool doesn't seem to support multi-volume drives.

All help/advice appreciated.

[Boot_WB]

Thanks Framiga, I'll give that a try.

[EDIT] - forgot to mention, the drive is split into 4 * 2.1GB partitions.

[Boot_WB]

I took the settings from the SFS.guide

SFS.guide:
Devices which can access data located anywhere in memory (a SCSI
controller which is embedded on an accelerator card, or a Zorro-III
IDE or SCSI controller) should have a mask of 0xFFFFFFFF.
....
In any case, if you have a SCSI drive, then a MaxTransfer value of
0x7FFFFFFF should be just fine.  For IDE drives, you probably need to
set it to 0x1FFFE or to 0xFFFE.  Those values represent 128 kB minus 2
bytes and 64 kB minus 2 bytes respectively.

Is this incorrect?

[Boot_WB]

This is weird.  I've just done the following tests on my system using a test file (Joe_Dirt.avi) from the OS3.9 disk of around 38MB:

Using mask 0x7fffffff
MaxT 0x00ffffff
Filesystem: SFS
Blocksize: 512 bytes
Buffers: 512
System ram: 194MB fast (60ns), 2MB chip

Partition - Partition (Same drive) = 24 seconds
Partition - RAM: = 27 seconds
Partition - Partition (between two drives) = 25 seconds
RAM - Partition = 16 seconds
RAM: - RAM: (copy between directories) = 21 seconds

I'm starting to wonder if there is some issue with having both the mediator and the bvision installed when running the system through the BVision.  When I get the motivation and time I'll try it with the mediator removed.

[Boot_WB]

Hi Alewis,

Thanks for the info.  I'll try removing the SE jumper, see if it makes a difference.  I'll also try setting (or removing, can't remember atm) the parity check jumper.

Good drives ain't they? :-) Someone was ebaying a bulk lot at £2 a piece recently, I got 10 - most of which now populate my PC and my Amiga, although I'm limited by the lack of available Molex connectors.

btw - you're right, the drives are 80-pin SCA, I didn't bother to mention it because they're the same logic as 68-pin versions, it's just the scsi ID, power, and options are set by the cable adapter attached to each drive using an 80-68pin SCA-SCSI adapter, as I have no rack to mount them in.  

If I had sufficient adapters, and an appropriate multi-headed 50-pin HD cable I'd try your suggestion, it was lack of the cable which prompted me to do the rather enlightening research to create the 50-68 pin hack in the first place, as the pitch of the 68-pin cable is the same as the 50-pin HD connector.

It never hurts to check (especially with SCSI) from the wires up, I have no hurt pride, but I really think it is filesystem/settings related rather than hardware - mainly due to the ~8MB transfer speeds I get on scsispeed checks, but also since the speed limitation is affecting my CDRW also, at approximately the same ceiling.

The slow file copying between directories of the RAM disk also suggests to me that something is wrong.  I need to find that memory speed checking program I used to have which showed 68k and PPC memory speeds.  Wish I could remember what it was called....