Robert Davis (3/4/2013)
ScottPletcher (2/28/2013)
Yes, that's the problem. You're scattering (small) I/Os all over the drive, causing lots of drive head movement, which is brutal on performance.Allocating "one drive" is very nebulous. Does this mean 2TB? 3TB? 5TB? No matter what SQL actually needs. How do you know ahead of time for a new instance what a massively-oversize, will absolutely never fill up drive size is? [Btw, how do you get the storage people to let you waste TBs of unused disk space on half-filled "tempdb drives"?]
We weren't talking size. We were talking whether or not additional files should be separated to a different drive. How is saying "on a single drive" nebulous?
There is no way to know what size could never possibly be filled up. That's true whether you pre-size the files out or not. Whether you pre-size or not, it doesn't change how you estimate how big the drive should be. You're really grasping at straws in an effort to continue arguing.
I don't waste TBs of space. You pulled that out of your backside, I never advocated having multi-TB drives for tempdb. You're so intent on arguing that you're making stuff up now. I aslo don't leave tempdb drives half-filled. I have stated many times in this thread that I pre-size the files out to consume at least 90% of the drive space. In what world is at least 90% allocated the same as half-filled?
"How is saying "on a single drive" nebulous?":
All drives aren't a fixed size; saying you allocate "a whole drive" to tempdb is nebulous as to the amount of space.
"I don't waste TBs of space."
This person needs 1.5G of space for tempdb. What's the smallest drive size you can realistically buy now? Add a few of those together and you're easily wasting TBs of space.
"In what world is at least 90% allocated the same as half-filled?"
Allocated is not the same as used. In this case, a, say, 400GB allocation would be 99% unfilled/unused.
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.