Re: raw devices - general questions

In article <328080BC.4984@mitre.org>, Peter Sylvester <peters@mitre.org> writes >David Williams wrote: >[clip] >> Sort of Informix can not access any part of the drive beyond the 2 >> gigabyte limit. This is because it uses the lseek() system call which >> only allow you to move to a postion up to 2 gigabytes into the drive. >> >> Therefore you need to use a Logical Volume Manager (LVM) to split the >> drive into what appears to be 2 x 2Gb) drives. Rather than one entry >> in /dev for the drive you will have two entrys in /dev one for each >> Logical Volume. >> >> Also be aware that if you are using ICL's Logical Volume Manager you >> will need to disable Informix Online's Kernel Asynchronous I/O feature >> by setting the environment variable KAIOOFF to 1 before you start >> Online 7.13. If not you will probably get data corruption (we got the >> Unix root partition (/) corrupted so bad it was not recoverable and we >> had to restore the complete machine from backups). This happen to us >> 4 times before Informix admiteed a problem... >> >> PS No part of this posting may be used by Oracle marketing people. >> I'm not having Oracle quote my Usenet posting as they have done to >> other people. Copyright David Williams 1996. >> >> -- >> David Williams > >Am I missing something here? >Why not just use the format command to partition the disk into (3) >partitions. The first one is a single track to reserve space for the >disk lable data, the other (2) split up the rest, into just under 2GB >each. Create (2) chuncks, each of which references the raw device file >for each partition (slices). The offsets will be zero for each. >I havn't tried it, but I would think it should work. As a general rule you should try and never use an offset of 0Kb. On some operating systems, the first couple of blocks of a slice holds slice information. I generally use an offset of 10Kb and that way I know that Informix is not going to overwrite that information. I fell into this trap on a Solaris 2.5 box and had to re-initialize my instance. HTH -- ######################################### # Neil Stevenson # # DSW Computer Systems Limited # # E-mail : neil@dsw2.demon.co.uk # # WWW : http://www.dsw2.demon.co.uk/ # # Voice : +44-1236-731330 # # Fax : +44-1236-731330 # #########################################