[Cialug] ssd raid

[David Bierce]

I've been told that SSDs will go into a readonly failure mode when run out
of good cells, I have run lots of data through many, many disk and have
never come across this mode.  The earlier OCZ, Samsung and Intel drives
I've had crash so bad the controller would lose state and require reboot.
I've had them fall off the bus never to return, I've had them start
returning 0 sector size.  The earlier series drives from everyone would
fail in batches with in a week of each other.

In production, ZIL/L2ARC for ZFS and Journals for Ceph so losing a bunch
together was annoying not fatal, but when they went bad, they all went down
in a mass suicide pact.  That said, once Intel moved passed the 5XX/7XX
series drives they have been amazing and I've run PBs through them without
issue.  For home I use the newer samsungs and only lightly abuse them with
great success.

I guess personal experience, is the same advise the old folk give for
creating arrays.  Don't get from the same batch, don't put your data in
single chassis, know all about the interface controller/HD controller
versions and issues and for SSDs know the wear you're going to put on the
drives and plan accordingly.  Also, prepare for an amazing speed
improvement,