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Think about availability. A large web site is going to keep replicated copies of data across many geographic locations, plus backed up in long term storage. Tho
by sweis 14y ago
Think about availability. A large web site is going to keep replicated copies of data across many geographic locations, plus backed up in long term storage. Those data are stored in hardware that is continually coming in and out of service. It's actually very hard to say with certainty that every copy of a particular piece of data has been deleted.
- cma 14y agoWhy should it ever be written to permanent storage?
- loeg 14y agoBecause RAM is orders of magnitude more expensive than spinning rust, or even SSDs.
- cma 14y agoThese are messages that last 20 seconds, there is no time that they will be on disk and not cached to ram anyway. (edit: well I guess it is 20 seconds after it is received)
- loeg 14y agoThe messages are stored for two days. Backups for 90… And: writing to (spinning) disk takes on the order of milliseconds. 20 seconds of RAM storage time (versus milliseconds) means several orders of magnitude larger working set size, which may well be larger than you can afford…