In this post I wanted to discuss few features about shared filesystems developed by Oracle as a solution to customers in a single plate.
OCFS has a GUI tool OCFSTOOL. Integrate well with RAC.Install 'fileutils-4.1-4.2-i386.rpm' for new cp and dd, even if on is using ASM can still use OCFS for trace files.
-Open source project developed and maintained by Oracle
-Version 1 available for Windows and Linux
-Separate code tree for Windows and Linux
-A true cluster filesystem
-Only supports Oracle datafiles, logfiles, archive log files, RMAN backups
-Do not use as a general purpose filesystem!
-Can be used a general purpose shared filesystem
-Is intended for shared operating system files and third party cluster apps
-Included in the mainstream Linux distributions
Repaclement for CFS (datafile,control and log files).Also useful for Non-RAC databases. A new instance type - ASM is introduces in 10g. ASM instance needs to start first to start any node and has no data dictionary.
-Disk Addition—Adding a disk becomes very easy. No downtime is required and file extents are redistributed automatically.
-I/O Distribution—I/O is spread over all the available disks automatically, without manual intervention, reducing chances of a hot spot.
-Stripe Width—Striping can be fine grained as in Redo Log Files (128K for faster transfer rate) and coarse for datafiles (1MB for transfer of a large number of blocks at one time).
-Buffering—The ASM filesystem is not buffered, making it direct I/O capable by design.
-Kernelized Asynch I/O—There is no special setup necessary to enable kernelized asynchronous I/O, without using raw or third-party filesystems such as Veritas Quick I/O.
-Mirroring—Software mirroring can be set up easily, if hardware mirroring is not available.
Third party solutions supported by Oracle:
Veritas (Supported by Oracle for Solaris, HP-UX, AIX)
CFS (True64) Supported by Oracle
GPFS (AIX) Supported by Oracle
Polyserve (Vendor support Linux, Windows)
Sistina (Vendor support - Linux)