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February 9, 2018 UPDATE
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Receipt today of a working Adaptec AHA1542B controller has provided
me the means to test and utilize SCSI support in Mach386.
Preliminary testing shows that the late-1992 Mach386 vmunix kernel
works well for SCSI disk. SCSI tape seems to have an issue wherein
it is writing an extra tape record when a tape device is closed after
writing.
This first SCSI Disk testing was performed with a Seagate ST15150N
Barracyda 4 drive. This drive is 4,294 Mbytes formatted, This is
exactly the 4GByte disk-size limit of the 32-bit Mach386 kernel.
The BSD UFS filesystem limit is 2GByte. Full testing of this drive
and the 4GB limit will occur in the next few days.
A 2GB (Max, for the BSD UFS architecture) can be created and mounted:
# df /mnt2 Filesystem 1024-blocks Used Available Capacity Mounted on /dev/sd0h 1969518 2 1772564 0% /mnt2
The SCSI Tape testing was first performed with a Seagate STD2401LW DDS-4
tape drive utilizing a DDS-1 tape. Various DDS tape drives were
actually tested, but I settled on this DDS-4 drive once I realized
that the extra block being written (and read) from the tape was
not specific to a particular drive.
Additional drive testing with a Quantum 4000 (TH5AA-YF) DLT tape
drive indicates the same sort of problems. Additionally, preliminary
testing there shows that at 20480-byte block size, the 20480th
byte of the first block is being written or read back incorrectly
as that byte fails comparison to the original data.
There are definitely problems with the st.c SCSI tape driver.
Today I also successfully mounted an NFSv2 filesystem from a FreeBSD 11.0
server onto Mach386:
# mount mod5:/tiny /nfs # df /nfs Filesystem 1024-blocks Used Available Capacity Mounted on mod5:/tiny -785220319 -1208500253 423279934 154% /nfs
Compare that to the server's reporting of that filesystem:
# df /tiny Filesystem 1K-blocks Used Avail Capacity Mounted on zpool1/tiny 12099681569 938983394 11160698174 8% /tiny
It will be interesting to see what issues arise.
