iscsi_initiator 2.2.2 slow to write and read

[Jiansong Liu]

On Mon, Jul 13, 2009 at 5:48 PM, Ivan Voras <ivoras at freebsd.org> wrote:

> Jiansong Liu wrote:
>
>> On Wed, Jul 8, 2009 at 1:36 AM, Gary Palmer <gpalmer at freebsd.org> wrote:
>>
>>  On Tue, Jul 07, 2009 at 07:05:03PM +0800, Jiansong Liu wrote:
>>>
>>>> Hello All,
>>>> .
>>>
>>> .
>>>>
>>>>  =iqn.1984-05.com.dell:powervault.md3000i.60024e80004e71a9000000004a011120
>>>
>>>         TargetAddress =192.168.4.182:3260,1
>>>>         tags =4
>>>> }
>>>>
>>> I'm no expert, but if that "tags" line refers to SCSI tags then that
>>> number is too small.  Try increasing it and see if that helps to
>>> address the problem.
>>>
>>> Regards,
>>>
>>> Gary
>>>
>>>
>> Hi Gary,
>>
>> Thanks for the advice, I have tried set tags to 32 and 64,
>> but it could not get more performance on IO (90MB write and 56MB read).
>> I think the writing is good enough for my application, but the reading
>> still
>> is a problem.
>>
>> # dd if=/home/mogdata/test.foo of=/dev/null
>> 2048000+0 records in
>> 2048000+0 records out
>> 1048576000 bytes transferred in 17.670549 secs (59340318 bytes/sec)
>>
>
> Are you really reading sector by sector? Try adding bs=1m to the dd line.
>
> There is something else you can try to increase sequential reading, if
> that's what you're interested in: increase the vfs.read_max sysctl to 32 or
> 64.
>
> On the other hand, it will do nothing to improve, and may harm random read
> performance. Test with your actual application before drawing conclusions.
>

Hi Ivan,It got 8MB/s better after adding bs=1m to the dd command.

Thanks for your notice, random read is more important to my application, it
is a image storage which stores pictures between 10KB~5MB, sequential
reading performance is not important.

Thanks all who kindly gave advice to me.

Best regards,
Liu Jiansong