Time to increase MAXPHYS?
Hans Petter Selasky
hps at selasky.org
Sun Jun 4 07:54:50 UTC 2017
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.
--HPS
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