Noah Dain noahdain at
Tue Sep 25 02:52:35 UTC 2007

On 9/24/07, Bart Silverstrim <bsilver at> wrote:
> Somebody, please tell me you're running Ubuntu on a Dell Poweredge
> system with a PERC controller.
> I'm running on a RAID 5 container and I believe I'm getting miserable
> disk throughput...
> sudo hdparm -Tt /dev/sda
> /dev/sda:
>   Timing cached reads:   944 MB in  2.00 seconds = 471.24 MB/sec
> HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate
> ioctl for device
>   Timing buffered disk reads:   42 MB in  3.10 seconds =  13.53 MB/sec
> HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate
> ioctl for device
> Hints?  Help?  Guidance?

perc 4 scsi3-320, 3 drives in raid5, ubu-6.06

sudo hdparm -Tt /dev/sda
 Timing cached reads:   3220 MB in  2.00 seconds = 1610.00 MB/sec
 Timing buffered disk reads:  154 MB in  3.43 seconds =  44.90 MB/sec

of more interest are the messages you get:
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate
ioctl for device

I've seen similar messages with cheap ide drives in the past, ones
that do not support explicit buffer flushes ( the drive's firmware
doesn't support it ).  However, I don't think there are any percs that
support ide drives.

Still, we don't know what kind of system you have.  If the system is
relatively new it probably has an sas (serial attached scsi)
controller.  However, sas controllers also support the much cheaper
sata drives.

Now typically there are two grades of sata drives.  Cheap consumer
(desktop grade) crap, and the faster more robust "enterprise/raid"
grade drives.  It could be that you have some cheap sata drives in
there with crappy firmware.  This could explain the low performance
and the HDIO_DRIVE_CMD errors.

Then again, you could have high-quality sas drives that have buggy
firmware which can be updated and fixed.  Again, just educated

next, you need to collect some data for us.

run: sudo lspci -v|less
and look for something describing your storage system.  for example,
the machine I tested hdparm on above shows entries like:

0000:02:04.0 SCSI storage controller: LSI Logic / Symbios Logic
53c1030 PCI-X Fusion-MPT Dual Ultra320 SCSI (rev 08)
        Subsystem: Dell PowerEdge 1800

0000:02:05.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID (rev 01)
        Subsystem: Dell MegaRAID 518 DELL PERC 4/DC RAID Controller

you also want to look at dmidecode's output to get a better idea of
what your system is:

sudo dmidecode|less

again, as a reference the system i tested on before:

System Information
        Manufacturer: Dell Computer Corporation
        Product Name: PowerEdge 1800
        Version: Not Specified
        Serial Number: A12B345
        UUID: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxx
        Wake-up Type: Power Switch

the "Serial Number" entry above is actually a Dell service tag.  You
can plug that number into and pull up some info on
your machine, as well as software updates.

Noah Dain
"The beatings will continue, until morale improves" - the Management

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