the real risk is the lack of power loss protection. Data can be
corrupted on unflean shutdowns
it's not! lack of "advanced power loss protection" only means lower iops
with fsync, but not the possibility of data corruption
"advanced power loss protection" is basically the synonym for
"non-volatile cache"
A few years ago - it was pretty common knowledge that if it didnt have
capacitors - and thus Power-Loss-Protection, then an unexpected power-off
could lead to data-loss situations. Perhapos I'm not updated with recent
development. Is it a solved problem today in consumergrade SSD?
.. any links to insight/testing/etc would be welcome.
https://arstechnica.com/civis/viewtopic.php?f=11&t=1383499
- does at least not support the viewpoint.
All disks (HDDs and SSDs) have cache and may lose non-transactional writes
that are in-flight. However, any adequate disk handles fsync's (i.e SATA
FLUSH CACHE commands). So transactional writes should never be lost, and
in Ceph ALL writes are transactional - Ceph issues fsync's all the time.
Another example is DBMS-es - they also issue an fsync when you COMMIT.
--
With best regards,
Vitaliy Filippov
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