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Posted by Brian Cryer on 05/24/05 13:15
"wriggs" <ian.w@btinternet.com> wrote in message
news:1116923667.752900.260220@f14g2000cwb.googlegroups.com...
> Hi,
>
> Any suggestions on the following as I've kind of run out of ideas.
>
> I have 2 servers which are the same spec ie box, processor etc. The
> only difference I can tell is that the production box has raid setup
> but the test box hasn't (I think).
>
> I have created a stored procedure to insert 10k rows into a dummy table
> with two columns.
>
> I have logged onto the boxes directly so there are no networks issues
> here. Also the boxes only have light traffic on them really, there
> isn't much going on at the point of running.
>
> The production box inserts the rows two times faster than the test box
> i.e 30 secs rather than 1 min. Does anyone have any idea why this could
> be, do you think it could be raid?
>
> The prod box has 8 disks I think in hardware Raid 5 but as the test box
> has 4 disks and it looks as if all the space is available i doubt raid
> is being employed.
>
> Thanks
>
> Ian.
>
> ps. does anyone know if there is a way to check the raid configuration
> of a box from within windows? or do you have to re-boot and go through
> the setup?
Regarding performance, if the disk arrangement is the only difference
between the two servers, i.e. same CPU, same memory then that leaves only
the disk configuration. (Its unlikely to have any noticeable bearing, but
you could check that neither system is using heavily fragmented disks.)
Your production box may have raid 5 and 8 disks but are you saying that all
8 disks are used in the raid to produce a single logical disk?
If you consider a raid 5 across 3 disks compared with a single disk system.
Each time you write 2MB of data, each of the 3 disks in the raid would have
1MB of data written, but the single disk system would need to write all 2MB
to the disk. Thus on paper the raid would give the impression of being twice
as fast (i.e only half the time to write). But if you were to change your
single disk system to a dual disk arrangement and have the log file and data
files on separate disks then you would get similar-ish performance to the 3
disk raid. The actual performance you get in reality is tempered by other
factors such as how much data you can push through the bus and how many
buses the disks are on, the characteristics of the individual disks, whether
you are using software or hardware raid and in the case of hardware raid the
characteristics of the raid controller (such as how large a cache it has and
whether it does write behind caching).
One other thought, on one of my Windows 2003 servers my sql server database
was crawling along when doing bulk inserts. It turned out to be that
write-behind caching on the disk (single disk system) was turned off. That
meant that each time sqlserver updated a data file or wrote to the log, it
couldn't carry on until the disk write had been completed. Turning on
caching in windows and it was much much faster.
As for checking the raid configuration from windows. If you are using a
software raid then you should be able to see the raid configuration from
within computer management > storage > disk management. If it is a hardware
raid then it may have come with a utility for allowing you to configure (or
monitor) it from within windows. You will need to check with the
manufacturer of the raid card. Failing that, reboot and the raid card should
give you the option to manage/view the raid configuration. If you do that
just be careful that you don't change the raid configuration - do that and
you loose your raid and everything on it.
Hope this helps,
Brian.
www.cryer.co.uk/brian
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