1*9b45ef44SBorislav Petkovmenuconfig RAS 2*9b45ef44SBorislav Petkov bool "Reliability, Availability and Serviceability (RAS) features" 3*9b45ef44SBorislav Petkov help 4*9b45ef44SBorislav Petkov Reliability, availability and serviceability (RAS) is a computer 5*9b45ef44SBorislav Petkov hardware engineering term. Computers designed with higher levels 6*9b45ef44SBorislav Petkov of RAS have a multitude of features that protect data integrity 7*9b45ef44SBorislav Petkov and help them stay available for long periods of time without 8*9b45ef44SBorislav Petkov failure. 9*9b45ef44SBorislav Petkov 10*9b45ef44SBorislav Petkov Reliability can be defined as the probability that the system will 11*9b45ef44SBorislav Petkov produce correct outputs up to some given time. Reliability is 12*9b45ef44SBorislav Petkov enhanced by features that help to avoid, detect and repair hardware 13*9b45ef44SBorislav Petkov faults. 14*9b45ef44SBorislav Petkov 15*9b45ef44SBorislav Petkov Availability is the probability a system is operational at a given 16*9b45ef44SBorislav Petkov time, i.e. the amount of time a device is actually operating as the 17*9b45ef44SBorislav Petkov percentage of total time it should be operating. 18*9b45ef44SBorislav Petkov 19*9b45ef44SBorislav Petkov Serviceability or maintainability is the simplicity and speed with 20*9b45ef44SBorislav Petkov which a system can be repaired or maintained; if the time to repair 21*9b45ef44SBorislav Petkov a failed system increases, then availability will decrease. 22*9b45ef44SBorislav Petkov 23*9b45ef44SBorislav Petkov Note that Reliability and Availability are distinct concepts: 24*9b45ef44SBorislav Petkov Reliability is a measure of the ability of a system to function 25*9b45ef44SBorislav Petkov correctly, including avoiding data corruption, whereas Availability 26*9b45ef44SBorislav Petkov measures how often it is available for use, even though it may not 27*9b45ef44SBorislav Petkov be functioning correctly. For example, a server may run forever and 28*9b45ef44SBorislav Petkov so have ideal availability, but may be unreliable, with frequent 29*9b45ef44SBorislav Petkov data corruption. 30*9b45ef44SBorislav Petkov 31*9b45ef44SBorislav Petkovif RAS 32*9b45ef44SBorislav Petkovendif 33