A DFS can be used from master servers, slave servers, development servers and collaboration servers and is created on the shared disk of a shared device.
The by-id name generated by the udev function is used as the shared disk device name. The by-id name is a device name generated from the unique identification information set in the hard disk.
Use of the by-id name enables each server to always use the same device name to access a specific disk.
Use either the udevinfo or udevadm command to ascertain the by-id name from the conventional compatible device name.
An example of checking the by-id name is shown below.
Example
Name of compatible device where file system is created: /dev/sdc
Under Red Hat(R) Enterprise Linux(R) 5:
# udevinfo -q symlink -n /dev/sdc <Enter> disk/by-id/scsi-1FUJITSU_300000370107 (omitted)
Under Red Hat(R) Enterprise Linux(R) 6:
# udevadm info -q symlink -n /dev/sdb <Enter> block/8:48 disk/by-id/ scsi-1FUJITSU_300000370107 (omitted)
Note
In order to use the by-id name checked using the udevinfo or udevadm command, "/dev/" must be added at the start of the name.
See
Refer to the online manual pages for details of the udevinfo and udevadm commands.
Note
If shared disk partition information is changed using the fdisk, parted, or similar command, refer to "4.2.4 Partition Information of Shared Disk Device Modified with fdisk(8) is not Reflected" in the "Primesoft Distributed File System for Hadoop V1 User's Guide" and refresh the partition information at all servers.
Point
The DFS file system can operate in either Logical Unit (physical) units or disk partition (logical) units.
If volume copy using ETERNUS SF AdvancedCopy Manager is performed, take into account the device units supported by ETERNUS SF AdvancedCopy Manager.
Refer to the "ETERNUS SF AdvancedCopy Manager Operation Guide" for ETERNUS SF AdvancedCopy Manager details.
