About RAID Technology

RAID (Redundant Array of Inexpensive Disks) devices might be used to contain the database and index tablespace files to provide protection against disk failure.

Hot-swappable RAID 0+1, or perhaps a RAID 5 device with large buffer cache, are recommended for the best combination of write performance and downtime prevention. Read performance will not usually be affected by RAID, as the database should reside almost entirely within the server's memory (System Global Area). Redo logs and Archived logs are accessed sequentially (usually for writes) and therefore are not ideally suited for being placed on a RAID-5 device. Also, datafiles that belong to temporary tablespaces and rollback segments should not be placed on a RAID-5 device.

Fault Tolerance and Data Availability with RAID

The following chart is designed to reflect the various RAID configurations and weigh the benefits on a scale of 1-5 (5 being least desirable):

  Independent Disks RAID 0 RAID 1 RAID 0+1 RAID 3 RAID 5
Random Read Access 2 1 2 1 5 1
Random Write Access 1 1 2 1 5 5
Sequential Performance 4 1 5 1 2 3
Data Protection 4 5 1 1 2 2
Cost of Redundancy 1 1 3 5 2 2

The benefits and drawbacks of each RAID configuration are spelled out in the table that follows.

Description of RAID arrays

RAID supplies fault tolerance and improves data availability
RAID 0 RAID 1 RAID 0+1 RAID 2 RAID 3 RAID 4 RAID 5
Striped disks (speed) Mirrored disks (reliable redundancy) Striping plus Mirroring Provides check disks with data 'bit-striped' across data and check disks Parallel data transfer Block or sector striping is done on the data disks, allows for multiple unrelated sectors to be read simultaneously. Distributed data and parity

  • Excellent sequential transfer rate performance and very good transaction rate performance
  • No redundancy
  • Low cost
  • Fully redundant copy of data on a second disk
  • Doubles the cost of storage
  • Both drives can be used for reads to improve performance
  • Excellent random write and transfer rate performance
  • Suitable for all-around performance and reliability
  • Expensive, data is completely duplicated
  • Detects and corrects single bit errors, detects double bit errors
  • Check disks consume 30% of the total disk array, complex to implement
  • A parity disk is used for a group of drives, the data written to the disk array is bit-striped across the data disks
  • Reduces overhead for check disk, consumes 20% of the total array space
  • Used for transaction processing systems
  • Write operations can become a bottleneck
  • Allows for multiple read and write operations simultaneously
  • Can have poor random write performance
  • Transfer rate and read transaction rate scale with the number of drives

Common RAID selections


  • RAID 0+1 for best protection and high transaction rates, most expensive.
  • RAID 5 for excellent protection, but willing to sacrifice possible loss in write performance, has excellent read performance.

So, with a RAID system the Oracle/ENOVIA Live Collaboration configuration solution may be as follows:


  • Raid 0+1: Data/Index datafiles, ENOVIA Live Collaboration User datafile, System datafiles, control files, Oracle/ENOVIA Live Collaboration installation, Rollback datafile
  • Raid 1: Redo Logs, Temp tablespace
  • Raid 1: Captured store data
  • External Disk: Backup disk, archive logs