The high availability features of the Oracle FS System allow the system to respond gracefully to an unexpected hardware or software failure that has the potential for service disruption. This feature keeps customer data accessible even during hardware replacement procedures.
Moves data from a temporary location to a newly replaced drive. For HDDs, the temporary location is an active spare strip. For SSDs, the temporary location is a dedicated spare drive.
Stores the original user data plus two sets of parity bits to help in the recovery of lost data. Access to the data is preserved even after the simultaneous failure of two drives. Double parity is implemented using RAID 6 technology and is the default redundancy level for the Storage Classes that specify the capacity-type media.
Unallocated strips on high-capacity hard disk drives (HDDs) in a given drive group. This spare capacity is striped across all of the HDDs in the drive group. Dynamic spares are used to support the RAID 5 protection level and the RAID 10 protection level. Dynamic spares cannot cross drive group boundaries.
A RAID level in which the Oracle FS System maintains an exact duplicate of a logical volume at a different location. No parity data is used. Mirroring protects against the loss of at least one drive and possibly more drives with an improvement of the performance of random write operations. Mirrored RAID is implemented using RAID 10 technology.
A feature of the Oracle FS System firmware that copies the data on a drive that has been predicted to fail to a spare drive or to a dynamic spare. This operation occurs before the suspect drive fails and is subsequently taken offline for replacement. This feature avoids the performance degradation and the potential exposure to data loss when the drive does fail. This feature optimizes overall performance by avoiding the overhead of rebuild operations. Sometimes referred to as copyaway.
As a benefit, the copyaway operation is performed while the data on the failing drive is redundant so that any errors that might exist can be corrected using the parity data. Also, because the failing drive remains online, data loss cannot occur if a second drive fails while the copyaway operation is in process.
Stores the original user data plus one set of parity bits to help in the recovery of lost data. Access to the data is preserved even after the failure of one drive. Single parity is implemented using RAID 5 technology and is the default redundancy level for the Storage Classes that specify the performance-type media.
An unused solid state drive (SSD) that can support the rebuilding of a drive group by means of copy-away operations. Drive Enclosures and drive groups do not contain an SSD that is dedicated only to this purpose. If, however, an unused SSD exists in a Drive Enclosure and if an SSD in that Drive Enclosure fails, is predicted to fail, or is removed, the system uses that unused drive to rebuild the problematic drive.
Furthermore, if no unused SSD exists, the system can use its parity data to continue functioning with a lost SSD.
A RAID optimization technique that groups multiple, small write operations to a particular stripe into a single write operation. This single write operation affects all LUNs that have unwritten data on that stripe. Write coalescing can increase the performance of random write operations that involve small amounts of data.
This optimization technique particularly benefits RAID 5 and RAID 6 storage arrays and auto-tiered LUNs.