Many applications or userids go and get TDISK in their PROFILE EXEC, and then seldom or never use it. Further, if they do have a problem, they increase the TDISK size, and never shrink it again.
Such users do lots of I/O to format the TDISK, and little else. Switching to VDISK will really help here -- no formatting I/O at all. On the other hand if you have applications that write large quantities of data to TDISK, perhaps as part of a sort, and then read it back in again, they may swamp your paging system. I don't know any easy way to tell the difference. One possibility is to limit VDISK per user, and go for TDISK when they have used up that limit. That's easy to do if you have a common EXEC that goes and gets TDISK, otherwise more difficult. (We issue USE TEMP100 to get 100 cylinders of TDISK.) We got an RVA, which did instant-format of TDISK, so we never used VDISK very much. We do use it for Linux Swap, though. On Tue, 24 Jan 2006 10:51:13 -0600, Mike Walter <[EMAIL PROTECTED]> wrote: >I second (or third) the motion to consider VDISK. \ > >For years I was worried that it would swamp our limited real storage (1G). > But in real-life experience it has been FANTASTIC! Even with two 3390-3s >reserved for TDISK, we used to frequently run into fragmentation. >Formatting VDISK is instantaneous (regardless of size), and the I/O is >awesome (no moving parts!). > >We've had a local TDISK EXEC here since almost day one. It just took a >small change, defaulting to VDISK (but allowed options to force it to be >allocated on with VDISK or TDISK). Happier (much) users, no more >fragmentation. Virtual life's great. > >Mike Walter >Hewitt Associates >The opinions expressed herein are mine alone, not my employer's.
