Valeri Galtsev wrote:
On Fri, September 8, 2017 9:48 am, hw wrote:
m.roth@xxxxxxxxx wrote:
hw wrote:
Mark Haney wrote:
<snip>
BTRFS isn't going to impact I/O any more significantly than, say, XFS.
But mdadm does, the impact is severe. I know there are ppl saying
otherwise, but I´ve seen the impact myself, and I definitely don´t
want
it on that particular server because it would likely interfere with
other services.
<snip>
I haven't really been following this thread, but if your requirements
are
that heavy, you're past the point that you need to spring some money and
buy hardware RAID cards, like LSI, er, Avago, I mean, who's bought them
more recently?
Heavy requirements are not required for the impact of md-RAID to be
noticeable.
Hardware RAID is already in place, but the SSDs are "extra" and, as I
said,
not suited to be used with hardware RAID.
Could someone, please, elaborate on the statement that "SSDs are not
suitable for hardware RAID".
When you search for it, you´ll find that besides wearing out undesirably
fast --- which apparently can be contributed mostly to less overcommitment
of the drive --- you may also experience degraded performance over time
which can be worse than you would get with spinning disks, or at least not
much better.
Add to that the firmware being designed for an entirely different application
and having bugs, and your experiences with surprisingly incompatible hardware,
and you can imagine that using an SSD not designed for hardware RAID
applications with hardware RAID is a bad idea. There is a difference like
night and day between "consumer hardware" and hardware you can actually use,
and that is not only the price you pay for it.
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