RE: Balancing disk drives

["Ketzes, Larry" <Larry.Ketzes@xxxxxxxxx>]

Great explanation Larry!

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of DrFranken
Sent: Friday, July 29, 2011 9:15 AM
To: midrange-l@xxxxxxxxxxxx
Subject: Re: Balancing disk drives

OK But it sounds as if you made a tactical error when you first added it 
by not using the "Add AND Balance" option. Rather it sounds like you did 
an "Add" followed by a "Balance" (with *CAPACITY).   These sound very 
very close but they are very much NOT.   The key difference is that with 
the former the drive is flagged to prevent any data getting on it until 
the balance is completed. Thus the system will FIRST fill it with an 
'average load' of stuff from the other drives and THEN make it available 
for new data. The latter process omits that flag and thus all the newest 
and frequently hottest data goes to that drive almost continuously until 
it's about evenly full with the other drives. The new drive in this case 
goes "hot".

Then you undertook the process of rebalancing for better performance.  
You collected three hours of data but in that three hours did you 
properly use all the stuff on that new drive? There is no guarantee that 
in that time frame you succeeded in running the right jobs to enable the 
system to perfectly balance that drive.

Finally while, yes, 10 is five times as much as 2, it's still only 10 
which ain't very busy.  Over time that will only get better.

     - Larry "DrFranken" Bolhuis

On 7/29/2011 8:50 AM, rob@xxxxxxxxx wrote:
> *This message was transferred with a trial version of CommuniGate(r) Pro*
> It was not well balanced on a usage standpoint previously.  We just added
> the drive this week and it dumped all new stuff into it.  It only took 3
> hours to balance it on usage.  Not counting the hours spent figuring the
> usage by tracing.
>
> What galled me was that the drive continues to get hammered.  Yes you're
> right, the first snapshot with the 15/100 ratio was quick.  However
> Elapsed time:   00:35:14
>    %
> Busy
> ...
>     2
>     2
>     2
>     1
>     2
>     2
>    10
> still shows it out of whack.
>
>
> Rob Berendt