1ec8f24b7SThomas Gleixner# SPDX-License-Identifier: GPL-2.0-only 29b45ef44SBorislav Petkovmenuconfig RAS 39b45ef44SBorislav Petkov bool "Reliability, Availability and Serviceability (RAS) features" 49b45ef44SBorislav Petkov help 59b45ef44SBorislav Petkov Reliability, availability and serviceability (RAS) is a computer 69b45ef44SBorislav Petkov hardware engineering term. Computers designed with higher levels 79b45ef44SBorislav Petkov of RAS have a multitude of features that protect data integrity 89b45ef44SBorislav Petkov and help them stay available for long periods of time without 99b45ef44SBorislav Petkov failure. 109b45ef44SBorislav Petkov 119b45ef44SBorislav Petkov Reliability can be defined as the probability that the system will 129b45ef44SBorislav Petkov produce correct outputs up to some given time. Reliability is 139b45ef44SBorislav Petkov enhanced by features that help to avoid, detect and repair hardware 149b45ef44SBorislav Petkov faults. 159b45ef44SBorislav Petkov 169b45ef44SBorislav Petkov Availability is the probability a system is operational at a given 179b45ef44SBorislav Petkov time, i.e. the amount of time a device is actually operating as the 189b45ef44SBorislav Petkov percentage of total time it should be operating. 199b45ef44SBorislav Petkov 209b45ef44SBorislav Petkov Serviceability or maintainability is the simplicity and speed with 219b45ef44SBorislav Petkov which a system can be repaired or maintained; if the time to repair 229b45ef44SBorislav Petkov a failed system increases, then availability will decrease. 239b45ef44SBorislav Petkov 249b45ef44SBorislav Petkov Note that Reliability and Availability are distinct concepts: 259b45ef44SBorislav Petkov Reliability is a measure of the ability of a system to function 269b45ef44SBorislav Petkov correctly, including avoiding data corruption, whereas Availability 279b45ef44SBorislav Petkov measures how often it is available for use, even though it may not 289b45ef44SBorislav Petkov be functioning correctly. For example, a server may run forever and 299b45ef44SBorislav Petkov so have ideal availability, but may be unreliable, with frequent 309b45ef44SBorislav Petkov data corruption. 319b45ef44SBorislav Petkov 329b45ef44SBorislav Petkovif RAS 336c36dfe9SBorislav Petkov 348636a1f9SMasahiro Yamadasource "arch/x86/ras/Kconfig" 356c36dfe9SBorislav Petkov 369b45ef44SBorislav Petkovendif 37