Michael Worobcuk wrote:
Am 21.07.2007 um 00:18 schrieb Tom Judge:
Michael Worobcuk wrote:
Tom Judge wrote:
As for performance issues with the SAS5/i, there is a problem in the
controller. A work arround was created by Scott Long which created
a sysctl that could be set to cause the controller to turn on the on
drive write cache's. These changes where commited to RELENG_6 on
2007-06-05 21:32:57 UTC.
...
Here is the original commit log:
scottl 2007-06-03 23:13:05 UTC
FreeBSD src repository
Modified files:
sys/dev/mpt mpt.c mpt.h mpt_cam.c
Log:
mpt.c:
mpt.h:
Add support for reading extended configuration pages.
mpt_cam.c:
Do a top level topology scan on the SAS controller. If
any SATA device are discovered in this scan, send a passthrough FIS
to set the write cache. This is controllable through the following
tunable at boot:
hw.mpt.enable_sata_wc:
-1 = Do not configure, use the controller default
0 = Disable the write cache
1 = Enable the write cache
The default is -1. This tunable is just a hack and may be
deprecated in the future.
I set mpt.enable_sata_wc to 1, as hw.mpt.enable_sata_wc is, AFAIK not
tunable in mpt_cam.c. This did not take any effect to the
performance. Is there anything else to change ?
Not that I know of, do you have SAS or SATA disks attached to the
controller?
yes, SAS.
In that case the above sysctl is not going to work for you as as the
name suggests it is only for sata devices.
For someone with a bit more SCSI experience than me: Could this be
solved by setting the WCE (Write cache enable) bit in the modepage (8)
on sas devices if it is not already set? The driver could make this
change on SAS devices during the topology scan in similar way to the way
it does for SATA devices?
Tom
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