Re: How do I use raw devices?

Bob,

In answer to your question you simply name the raw devices in the install process or in the create tablespace command. Points to watch are that the devices are owned by the oracle userid, chgrp dba and chmod 600. These devices are usually of the form /dev/rdsk/c?t?d0s? - note the rdsk not dsk. Also make sure the partition starts at cylinder 1 so as not to overwrite the disk label.

1. Performance will be increased at peak throughput only.
2. If you want to make a file system on disk quickly however big use the -i option the the newfs command. eg newfs -v -i 32768 /dev/rdsk/c?t?d0s? Using this I have seen a single 48GB file system created in under 15 minutes.
3. To balance I/O always use Sun's Online disksuite product as this makes life very simple. (it isn't that expensive!) and then either put a file system and database on striped UFS disk or use raw disk I/O to a striped meta device. Make the stripe as wide as you want - internal we have used up to 24 - 30 disks.
4. If you want this kind of flexibility then raw disk is probably out as you can currently only have 7 partitions per disk.
5. You can mix raw and UFS.
6. How about Oracle Parallel Backup ? :-)

Tim

---