On Sat, 03 Feb 2018 18:49:50 +0000 "Digby R.S. Tarvin" <digby...@gmail.com> wrote: Digby R.S. Tarvin writes: > > My experience of running normal (read mostly) Linux filesystems on solid > state media is that SSD is more robust but far less reliable than rotating > media. > > MTBF for rotating media for me has been around 10 years. MTBF for SSD has > been about 2. And the SSD always seems to fail catastrophically - appearing > to work fine one day, then after an inexplicable crash, half the media is > unreadable. I assume this is something to do with the wear leveling, which > successfully gets most of the blocks to wear out at the same time with no > warning. If I reformat and reload the SSD to correct all the mysterious > corruptions, it last a few weeks, then does the same thing again.
MTTF doesn't make much sense for SSDs. A 1TB SSD I bought a couple years ago has a rating of 300 TB written, an MTBF of 2M hours and a 10 year warranty. It can do over 500MB/s of sequential writes. If I average 9.5MB/s writes, it will last year. If I continuoulsy write 100MB/s, it will last under 35 days. In contrast the life of an HDD depends on how long it has been spinning, seeks, temperature and load/unloads. A disk with 5 year warraty will likely last 5 years even if you write 100MB/s continuously. And consumer HDSC cards such as the ones used in cameras and Raspi are much much worse. In practice an SSD will last much longer than a HDD since average write rates are not high for the typical things people do.