RAM-SANTM Backup Methods


RamSan-520 Only

All storage devices should be supported by reliable backup procedures to ensure the integrity of the stored data.  This is especially true of SDRAM-based storage devices, since SDRAM is inherently volatile.  For this reason, power should not be removed from the RAM-SAN unless a separate copy of the data has been stored in a non-volatile external backup.  Several different options exist for implementing such a backup, ranging from simple to sophisticated, with the choice of a specific backup option left to the user.

The simplest RAM-SAN backup solution is to have the RAM-SAN mirror all write operations to a network RAID.  Simply adding a RAM-SAN to an existing storage area network and configuring it for mirrored storage operation achieves this goal.  All READ operations are serviced by the RAM-SAN for maximum performance, while all WRITE operations are performed simultaneously by the RAM-SAN and a network RAID for maximum data persistence.  This approach offers the best of both worlds performance and persistence and provides the added benefit that the RAM-SAN can serve as a short-term backup for the RAID device.

Another method encouraged by most SSD suppliers is the use of a dedicated hard disk (or RAID) to which the SSD will dump data under conditions of impending power failure.  If such a failure is detected in one of the RAM-SAN's hot-swappable redundant power supplies, the RAM-SAN can store the entire contents of its memory to this device.  Devices for this purpose may be supplied by TMS or by a third party, allowing maximum flexibility in the choice of a particular backup method.  Users may opt for a very fast and sophisticated backup method, a relatively simple backup method, or no backup method at all.

In support of these backup methods, TMS supplies a dedicated RAID controlled by the RAM-SAN.  This RAID can be configured for mirrored storage operation or for dedicated power-failure backup operation.  Depending upon the particular external storage device, a full-capacity RAM-SAN (128 Gbytes) can be dumped to disk in as little as 30 minutes.  For smaller-capacity RAM-SANs, the maximum required backup time decreases linearly with decreasing memory capacity.