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:

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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