Hi Rugxulo,

that mail/quote was a bit long, trying to summarize ;-)

- UDMA XDMA XCDROM (-2/2006) are only for IDE/ATAPI

- GCDROM XGCDROM are based on XCDROM and might work
   for SATA (XGCDROM: SATA+ATAPI) but tend to fail.

   (possibly BD, HD-DVD?) and harddisks. UIDE also has
   a cache for all drives and a BIOS based floppy cache.
   For AHCI boards, set the BIOS to native IDE / legacy.

- to access SATA CD/DVD/..., you should use UIDE(JR)
   and not the old drivers. Also supports IDE/ATAPI.

- using UIDE(JR) also gives better protected mode DMA
   stability and performance than BIOS for harddisks if
   (J)EMM(386/EX) / protected mode is used. Recommended.

- using caches is recommended (UIDE, lbacache, cdrcache)
   for example because metadata (FAT, directories) are
   accessed sector by sector (also read-ahead, tickle?)

- the UIDE on ibiblio needs update (15 Aug 2010) and the
   old UDMA XDMA XCDROM GCDROM should be marked as old.

I think we should still keep the old drivers for reference
be we should indeed have them "less announced" (e.g. LSM).

Talking about read-ahead, I think that in particular for
SSD it would be very interesting to do even a small amount
of write pooling... This is because SSD are very fast with
seek and read but each write has some delay. Writing larger
blocks less often is therefore faster than many small ones.

I would suggest to experiment with something like 4-64 kB
cache pool size a sub-second maximum age of dirty sectors.
This still gives data and metadata the chance to accumulate
to some/much larger chunks while keeping the risks limited.

Regards, Eric

> http://johnson.tmfc.net/dos/driver.html
> www.ibiblio.org/pub/micro/pc-stuff/freedos/files/dos/udma/

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