Raw LVM devices on Linux

I'm having a difficult time finding a definitive answer to the proper usage of raw devices on Linux. We are running IDS 9.40 on SLES9 using LVM partitions for our dbspaces. We use soft links to the /dev/volgroup/volname files. While this clearly is not "cooked" file system space, is it buffered by the OS? The /dev/volgroup/volname devices are block devices, not character devices: brw-rw---- 1 informix informix 253, 5 Sep 29 20:33 vg1-disk1 If you do some Googling on the subject, you'll find out about /dev/raw/rawN devices, which ARE character devices. And that's what I've always believed is a proper raw device for Informix. I've set up a test machine (CentOS 4.2) using /dev/raw: crw-rw---- 1 root disk 162, 1 Mar 14 14:05 raw1 As a side note: When using /dev/raw, the owner and group do not stick because the devices are created at each boot. But Informix does not seem to mind as long as you chown informix:informix just before creating the dbspace. This SuSE link has instructions for using /dev/raw: http://www.novell.com/products/linuxenterpriseserver8/whitepapers/LVM.pdf But this IBM link instructs you to link directly to /dev/hdbN: http://www-128.ibm.com/developerworks/db2/library/techarticle/dm-0603breitfeld/ Ignore the 'db2' in the url path, the article is about Informix. It's not LVM, but they still don't mention /dev/raw So, what's the scoop? Are both /dev/whatever and /dev/raw unbuffered? -- Jeff jlar310 at yahoo

Jeff wrote: > > So, what's the scoop? Are both /dev/whatever and /dev/raw unbuffered? > AIUI until IDS10 you have to use raw however in 9.3 ( I dont have SLES ) /etc/raw is borked See http://forge.novell.com/modules/xfmod/newsportal/article.php?group_id=1459&msg_id=19035&group=novell.support.suse.linux.professional -- Clive