On 0604T0952, Hans Petter Selasky wrote: > On 06/04/17 09:39, Tomoaki AOKI wrote: > > Hi > > > > One possibility would be to make it MD build-time OTIONS, > > defaulting 1M on regular systems and 128k on smaller systems. > > > > Of course I guess making it a tunable (or sysctl) would be best, > > though. > > > > Hi, > > A tunable sysctl would be fine, but beware that commonly used firmware > out there produced in the millions might hang in a non-recoverable way > if you exceed their "internal limits". Conditionally lowering this > definition is fine, but increasing it needs to be carefully verified. > > For example many USB devices are only tested with OS'es like Windows and > MacOS and if these have any kind of limitation on the SCSI transfer > sizes, it is very likely many devices out there do not support any > larger transfer sizes either.
FWIW, when testing cfiscsi(4) with Windows and OSX I've noticed that both issue 1MB requests. I wouldn't be surprised if they avoided doing that for older devices, depending on eg the SCSI version reported by device. _______________________________________________ freebsd-current@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
