Re: HPUX V10.01 and Raw Devices

I have set up several Oracle databases, both V6 and V7, using HPUX LVM raw devices under HPUX 9.04, and have found they perform adequately. I have set up the raw volumes wherever I thought best, for space allocation and disk performance needs, then used a single directory to hold a series of symbolic links to those raw logical volumes. There may be a performance hit for using the links, but I found it smoothed the naming conventions, and gave me the flexibility to put replacement LVMs (if necessary, e.g. after a disk crash) wherever they would fit, and I could then just repoint the links to make Oracle happy. A few caveats:

1. Use the raw character device as the Oracle datafile in the CREATE TABLESPACE statement.
2. Set permissions to crw-rw-rw- for the given LVMs.
3. When specifying the size, remember that Oracle uses a 1-block overhead in setting up a datafile. This (Oracle) block size is 2k under HPUX 9.04 (and is probably also 2k under HPUX 10, but may be some other value). The size of the Oracle tablespace is thus (size of LVM - 2k), and the exact number must be specified by doing the arithmetic and putting the result in the SIZE clause of the CREATE TABLESPACE statement. For example, a 100 Mb tablespace would be (100*1024*1024) - 2048, or 104855552 bytes.

Good luck!

mbm

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