More Adaptec 29320 + Seagate ST336607LW woes

[Don Lewis]

On  6 Dec, Nate Lawson wrote:
> On Sat, 6 Dec 2003, Don Lewis wrote:

>> One place where folks have noticed a performance difference between WCE
>> on and WCE off is when using newfs after we got rid of the buffered
>> block devices and forced newfs to use the raw character device.  Newfs
>> only issues one write() at a time and waits for the status before
>> issuing another write().  If WCE is on, the writes only have to hit the
>> drive cache before the drive returns a status that gets returned to
>> userland, but if WCE is off the data has to hit the platter before the
>> status is returned, which slows down newfs quite considerably.  Tagged
>> queuing doesn't make any difference in this case because the drive will
>> only see at most only one command at a time.
> 
> Great explanation.  We should probably add write clustering to newfs at
> some point.

Yes, but it is somewhat less of an issue now that UFS2 does lazy inode
initialization.