Jesper Krogh wrote:
A Battery Backed raid controller is not that expensive. (in the range
of 1 or 2 SSD disks).
And it is (more or less) a silverbullet to the task you describe.
Maybe even less; in order to get a SSD that's reliable at all in terms
of good crash recovery, you have buy a fairly expensive one. Also, and
this is really important, you really don't want to deploy onto a single
SSD and put critical system files there. Their failure rates are not
that low. You need to put them into a RAID-1 setup and budget for two
of them, which brings you right back to
Also, it's questionable whether a SSD is even going to be faster than
standard disks for the sequential WAL writes anyway, once a non-volatile
write cache is available. Sequential writes to SSD are the area where
the gap in performance between them and spinning disks is the smallest.
Plugging your system (SSD's) with an UPS and trusting it fully
could solve most of the problems (running in writeback mode).
UPS batteries fail, and people accidentally knock out over server power
cords. It's a pretty bad server that can't survive someone tripping
over the cord while it's busy, and that's the situation the "use a UPS"
idea doesn't improve.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg@xxxxxxxxxxxxxxx www.2ndQuadrant.us
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