Re: [9fans] Is fossil/venti file system a good choice for SSD?

[Bakul Shah <bakul@bitblocks.com>]

On Sat, 03 Feb 2018 18:49:50 +0000 "Digby R.S. Tarvin" <digbyt42@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.