Some manufacturers simply fit more fans than are needed, while others fit two fans in each position, to maintain optimum airflow when a failure occurs. As with power units, load sharing can prolong the life of the fans, which can also be made hot-swappable so that they can be replaced without powering down the server. But it is not just ancillary components like power supplies and fans that can benefit from redundancy. There are systems on the market that can tolerate an individual processor failure, such as the Tandem Non-Stop Himalaya server, but these are beyond the budgets of many businesses. More mainstream Intel-based servers can now be set to reboot when such a problem arises, and restart with the faulty CPU disabled, which is the next best thing.
Memory also benefits from redundancy.
The ECC information is based on the contents of individual memory bits and is recalculated every time the data is accessed. The memory controller compares the results against the stored values so that if a memory fault occurs it can be fixed on the fly. All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of ZDNetUK is prohibited. ZDNetUK and the ZDNetUK logo are trademarks of Ziff-Davis Publishing Company.