Format hard disk

[Ngoh Chean Siung]

Hi,

Just wonder what is the difference between cooked & blocked device file?

regards

[Geoff Wild]

Cooked & block? That means the same thing.

All cooked (or block) disks are located in /dev/dsk.

Some database vendors may recommend bypassing the file system (using raw logical volumes) for best performance. With newer disk arrays like the XP, performance on "cooked" volumes is equivalent.

Rgds...Geoff

[Bill Hassell · Accepted solution]

Actually, they point to the same disk but use different drivers. That's why the major number is different. A raw devicefile points directly to the disk, no special processing. The blocked or cooked devicefile uses a driver that first routes the data to the buffer cache in RAM. This is why opening a large file for the first time in vi takes a while, but the second time, it's almost instantaneous. The blocked driver is optimized for filesystems so using it as an Informix disk will slow things down by routing the raw Informix read/write activity into the buffer cache.