30 hours to format a LUN on 8400

[Nelson Jeppesen]

It took 25 hours to do a full format of a 1TB LUN from windows at about 11MB/S on a Windows 2008r2 box. It was NOT a quick format and before you ask the EVA, disk, HBA, MPIO, windows patches are all to the latest version. The disk group has (100) 15k 500GB FC drives.

This is 100% re-producible. Any ideas?

[Uwe Zessin]

Use quick format ;-)

Seriously, the full format has always been 'slow'. I don't know what it does exactly during that time, but I don't believe it really does overwrite all blocks.
I have a dim memory that I looked into this a loong time ago and saw a lot of read I/O instead of writes.

[S. Boetticher]

I agree with Uwe's recommendation...

since we use EVAs we always had loooong full formats for VDisks, so we only use quick formats and never had any issue due to this.