
1-48 IBM Informix OnLine Database Server Administrator’s Guide
OnLine Disk Space Allocation
Raw File Space
Consult your UNIX system manuals for instructions on how to create and
install a raw device.
In general, you can either repartition your disks or unmount an existing file
system.Ineithercase,takeproperprecautionstobackupanyfilesbeforeyou
unmount the device.
Change the group and owner of the character-special devices to informix.
(The filenameof thecharacter-special device usually begins with the letter r
(for example, /dev/rsd1f).
Verify that the UNIX permissions on the character-special devices are 660.
Usually,the character-specialdesignation and devicepermissionsappear as
crw-rw---- if you execute the UNIX ls -l command on the filename. (Some
UNIX systems vary.)
Many UNIX systems keep partition information for a physical disk drive on
the driveitself ina volumetable ofcontents (VTOC). The VTOC is commonly
stored on the first track of the drive. A table of alternate sectors (and bad-
sector mappings) can also be stored on the first track.
If you plan to allocate partitions at the start of a disk, use offsets to prevent
OnLine from overwriting critical information required by UNIX. Specify an
offset for the root dbspace or its mirror with the ROOTOFFSET and
MIRROROFFSET parameters, respectively.
Create a link between the character-special device name and another
filename with the UNIX link command, usually ln.
Do not mount the character-special device. Do not create file systems on the
character-special devices.
ExecutetheUNIX commandls -lgonyourdevicedirectorytoverifythatboth
the devices and the links exist. An example output follows, although your
UNIX system display might differ slightly:
crw-rw---- 1 informix Mar 7 14:30 /dev/rxy0h
crw-rw---- 1 informix Mar 7 14:30 /dev/rxy0a
lrwxrwxrwx 1 informix Mar 7 15:15 /dev/my_root@->/dev/rxy0h
lrwxrwxrwx 1 informix Mar 7 15:15 /dev/raw_dev2@->/dev/rxy0a
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