Hi! 

I have a Dell 1435 with folowing LSI config: 

mpt0:vol0(mpt0:0:0): Settings ( Hot-Plug-Spares High-Priority-ReSync ) 
mpt0:vol0(mpt0:0:0): Using Spare Pool: 0 
mpt0:vol0(mpt0:0:0): 2 Members: 
(mpt0:1:32:0): Primary Online 
(mpt0:1:1:0): Secondary Online 
mpt0:vol0(mpt0:0:0): RAID-1 - Optimal 
mpt0:vol0(mpt0:0:0): Status ( Enabled ) 
(mpt0:vol0:1): Physical (mpt0:0:1:0), Pass-thru (mpt0:1:0:0) 
(mpt0:vol0:1): Online 
(mpt0:vol0:0): Physical (mpt0:0:32:0), Pass-thru (mpt0:1:1:0) 
(mpt0:vol0:0): Online 
da0 at mpt0 bus 0 target 0 lun 0 
da0: <Dell VIRTUAL DISK 1028> Fixed Direct Access SCSI-5 device 
da0: 300.000MB/s transfers 
da0: Command Queueing enabled 
da0: 237464MB (486326272 512 byte sectors: 255H 63S/T 30272C) 


Here is simple test 

[root@FreeBSD tmp]# dd if=/dev/zero of=1g bs=1M count=1000 conv=sync 
1000+0 records in 
1000+0 records out 
1048576000 bytes transferred in 196.386202 secs (5339357 bytes/sec) 

[root@FreeBSD tmp]# time $(dd if=/dev/zero of=1g bs=1M count=1000 ; sync) 
1000+0 records in 
1000+0 records out 
1048576000 bytes transferred in 198.980241 secs (5269749 bytes/sec) 

real	3m24.876s 
user	0m0.002s 
sys	0m1.869s 

So I've got _only_ 5Megabytes per second. 
Now is the same server under RHEL5 

[root@RHEL5 tmp]# dd if=/dev/zero of=1g bs=1M count=1000 conv=sync 
1000+0 records in 
1000+0 records out 
1048576000 bytes (1.0 GB) copied, 5.34952 seconds, 196 MB/s 

[root@RHEL5 tmp]# time $(dd if=/dev/zero of=1g bs=1M count=1000 ; sync) 
1000+0 records in 
1000+0 records out 
1048576000 bytes (1.0 GB) copied, 4.70584 seconds, 223 MB/s 

real	0m42.567s 
user	0m0.007s 
sys	0m6.038s 

Both systems default install, no tweaking or custom kernels. 
FreeBSD 8.0-release is on UFS, RHEL is on ext3. 
I've tried same test on zfs/ufs FreeBSD 7.2 and 8.0 and got always about
6megabytes per sec.

Fix: 

N/A
How-To-Repeat: Perform tests on hardware described.