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Message Posted: Thu, 03 Apr 2003 @ 14:36:41 GMT


     
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Subj:   Re: Out of spool spcae on disk
 
From:   Lewis, Huw

If you are running a heavily-skewed query and it has caused your machine to run out of available spoolspace on a vproc, then you may well have allocated individual users too much spoolspace. Allocating a ton of spoolspace just to ensure queries get through is not necessarily the best way to manage your system, as it can let poor (skewing or bad product join) queries get through, with their associated impact on other users.

Possibly, you have a lot of users active at a point in time, and they are using all the spool available in an even fashion, with a skew from one user causing the problem, but it needn't necessarily be a massive skew in this case.

Another possible explanation is that the number of cylinders available for spool is small, and you have some degradation of space utilised per cylinder (both determined from Showspace utility). Running Showspace on a regular basis (it has no system impact) will allow you to get an idea of the disk utilisation on your system. If you also collect total spool usage at the same time, you will get a good feel for what the problem is. If the average utilisation per cylinder is dropping over time, then you can look at Freespace percentages, usually on your larger or more frequently updated tables. If the number of cylinders being used by spool is large, then concurrent user activity is causing your problem, and the only real solution is more disk, as constraining your users tends to be a bad idea. If the number of Free Cylinders (i.e. available for spool) is low when the system is quiet, then you either need to reduce your Freespace percentage or need more disk. Some combination of these issues is likely.

You can run a Packdisk utility to restore free space. Running Packdisk on a regular basis is usually an indication that your machine is approaching its limits in terms of perm space, or that you need to play around with your free space percentages, possibly on a table-by- table basis.

Refer to the Teradata Utilities Volume 1 manual (A-K) for the Ferret utility, from within which Showspace and Packdisk can be run.



     
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