This assumption was wrong for Intel Optane memory. Power loss could cut the data stream anywhere in the middle. (Note: the DIMM nonvolatile memory version)
consumer Optane were not "power loss protected", that is every different than not honoring a requested a synchronous write.
The crash-consistency problem is very different than the durability of real synchronous writes problem. There are some storage devices which will lie about synch writes, sometimes hoping that a backup battery will allow them to complete those write.
System crashes are inevitable, use things like write ahead logs depending on need etc... No storage API will get rid of all system crashes and yes even apple games the system by disabling real sync writes, so that will always be a battle.
You're missing the point. GP was mentioning the common assumption that all systems in the last 30 years are sector-atomic under power loss condition. Either the sector is fully written or fully not written. Optane was a rare counter example, where sector can become partially written, thus not sector-atomic.
Really? A 512-byte sector could get partially written? Did anyone actually observe this, or was it just a case of Intel CYA saying they didn't guarantee anything?
Yes, really. "Crash-consistent data structures were proposed by enforcing cacheline-level failure-atomicity" see references in: https://doi.org/10.1145/3492321.3519556
nyrikki|1 year ago
The crash-consistency problem is very different than the durability of real synchronous writes problem. There are some storage devices which will lie about synch writes, sometimes hoping that a backup battery will allow them to complete those write.
System crashes are inevitable, use things like write ahead logs depending on need etc... No storage API will get rid of all system crashes and yes even apple games the system by disabling real sync writes, so that will always be a battle.
yuboyt|1 year ago
lmm|1 year ago
yuboyt|1 year ago