Re: FreeBSD 5.3b7and poor ata performance

Kenneth Culver said:

> Quoting fandino <fandino_at_ng.fadesa.es>:
>
>> Søren Schmidt wrote:
>>>> # dd if=/dev/ad4 of=/dev/null bs=1024k count=1024
>>>> 1024+0 records in
>>>> 1024+0 records out
>>>> 1073741824 bytes transferred in 31.090536 secs (34535970 bytes/sec)
>>>
>>> etc, and I get this:
>>> 1073741824 bytes transferred in 18.488903 secs (58074934 bytes/sec)
>>> 1073741824 bytes transferred in 14.956484 secs (71791059 bytes/sec)
>>
> ad4: 114440MB <Maxtor 6Y120M0/YAR51EW0> [232514/16/63] at ata2-master
> SATA150
> ad6: 114440MB <Maxtor 6Y120M0/YAR51EW0> [232514/16/63] at ata3-master
> SATA150
>
> Set up for striping:
>
> ar0: 228880MB <ATA RAID0 array> [29178/255/63] status: READY subdisks:
>   disk0 READY on ad4 at ata2-master
>   disk1 READY on ad6 at ata3-master
>
> I get the following performance with dd:
>
> dd if=/dev/ad4 of=/dev/null bs=1m count=200
> 200+0 records in
> 200+0 records out
> 209715200 bytes transferred in 3.538456 secs (59267433 bytes/sec)
>
> dd if=/dev/ad6 of=/dev/null bs=1m count=200
> 200+0 records in
> 200+0 records out
> 209715200 bytes transferred in 3.551439 secs (59050767 bytes/sec)
>
> dd if=/dev/ar0 of=/dev/null bs=1m count=200
> 200+0 records in
> 200+0 records out
> 209715200 bytes transferred in 1.837508 secs (114130226 bytes/sec)
>
> This is with a custom kernel with all debugging options off. I haven't
> seen a
> mail from you yet that says whether you turned off debugging options in
> the
> kernel or not, and if you haven't turned off debugging options, I'd
> strongly
> suggest doing so.

Out of curiosity, i ran this on one of our production servers, which runs
on a dual Xeon MB, with SCSI raid-10 setup, and to my surprise here are
the results:

CPU: Intel(R) Xeon(TM) CPU 2.80GHz (2799.22-MHz 686-class CPU)
real memory  = 2146959360 (2047 MB)
avail memory = 2099650560 (2002 MB)
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs

da0 at asr0 bus 0 target 0 lun 0
da0: <ADAPTEC RAID-10 3B0A> Fixed Direct Access SCSI-2 device

FreeBSD 5.3-BETA4 #0: Sun Sep 12 13:09:43 EDT 2004

(Custom kernel, no debugging)

# dd if=/dev/da0 of=/dev/null bs=1m count=200
200+0 records in
200+0 records out
209715200 bytes transferred in 6.225309 secs (33687517 bytes/sec)

Why is a SCSI raid-10 system slower than a plain IDE disk? Something is
wrong here.