Raw DiskSpace for the first time

Hi there : This is the first time I try to use raw disk space instead of cookied disk space. My platform is RedHat Linux 6.2 and Informix IDS 7.2 . I have a SCSI disk at /dev/sdb and make a partition on it (sdb1) , and then set a link "rootdisk" to "/dev/sdb1". So I set the parameter "ROOTPATH" in ONCONFIG like : ROOTPATH /opt/informix/workspace/rootdisk When I try to initiate by using "oninit -i" I get an error message : Segmentation failed I know I'm doing something wrong , but I need your help to resolve. Is it OK to use the whole partition(partitioned , not formatted) as a raw device ? Or I gave the wrong name for raw device ? Thanks in advance. Ken

Check permissions on the device, they should be owner: informix, group: informix, chmod 660. Also note that unless you have the new Raw I/O module, which is NOT distributed with RH6.2, and you use the /dev/rsd* device you are NOT using RAW disk. You are not using a filesystem file but you are still going through the Linux buffer cache and so are not using RAW disk which would bypass the Linux buffers. (Rumors have it that RAW devices will be officially part of the 2.4.xx kernel and so will probably be delivered with RH 6.3 or so) . Art S. Kagel ken@atlas.net.tw wrote: > Hi there : > > This is the first time I try to use raw disk space instead of > cookied disk space. > My platform is RedHat Linux 6.2 and Informix IDS 7.2 . > > I have a SCSI disk at /dev/sdb and make a partition on it (sdb1) , > and then set a link "rootdisk" to "/dev/sdb1". > So I set the parameter "ROOTPATH" in ONCONFIG like : > > ROOTPATH /opt/informix/workspace/rootdisk > > When I try to initiate by using "oninit -i" I get an error message > : > > Segmentation failed > > I know I'm doing something wrong , but I need your help to > resolve. > Is it OK to use the whole partition(partitioned , not formatted) > as a raw device ? Or I gave the wrong name for raw device ? > > Thanks in advance. > > Ken >

Thanks for your replying at first... So , you mean I need to use the new RAW I/O module first , right ? How can I do that , download some kind of patch and then re-build my kernel , or it is possible only in the new version of Linux kernel ? Is it right that it means there's no way to use "true" Raw Disk Space in Linux platform right now ? Thanks a lot !! Ken >Also note that unless you have the new Raw I/O module, >which is NOT distributed with RH6.2, and you use the /dev/rsd* device you >are NOT using RAW disk. You are not using a filesystem file but you are still >going through the Linux buffer cache and so are not using RAW disk which >would bypass the Linux buffers.

ken@atlas.net.tw wrote: > Thanks for your replying at first... > > So , you mean I need to use the new RAW I/O module first , right ? > How can I do that , download some kind of patch and then re-build my > kernel , or > it is possible only in the new version of Linux kernel ? Exactly. You have to get the source for the RAW IO module, compile it, and build a new kernel with it or at least list it in the modules list for dynamic loading (actually I don't know if it is a loadable module or a hard-link module). > Is it right that it means there's no way to use "true" Raw Disk Space in > Linux > platform right now ? A fairly solid version is available for the 2.2.xx kernels and a less mature version was available for the 2.0.xx kernel, but it is an optional evaluation module (or whatever Linus calls such unofficial things, in the 2.2.xx kernel. It is part of the main development path in the current 2.3.xx kernel and should be part of the released 2.4.xx kernels when 2.3.xx moves from development to production. It seems that Linus was (perhaps still is) morally opposed to RAW IO and felt that there was no valid need for it in Linux. Someone external developed the module and announced it and then a hoard of database folk like us petitioned for its inclusion. Thus the system works and Linux is still the user developed OS. Art S. Kagel > > Thanks a lot !! > > Ken > > >Also note that unless you have the new Raw I/O module, > >which is NOT distributed with RH6.2, and you use the /dev/rsd* device > you > >are NOT using RAW disk. You are not using a filesystem file but you are > still > >going through the Linux buffer cache and so are not using RAW disk which > >would bypass the Linux buffers.