We thought a lot about correlated storage failures - especially with regard to SSDs - as we rebuilt our infrastructure circa 2012/2013.<p>In the end, the low hanging fruit - or, the biggest actionable takeaway - was that <i>when we build boot mirrors out of SSDs, they should not be identical SSDs</i>.<p>This was a hunch I had, personally, and I think experience and, now, results like these, bear it out.<p>Consider: an SSD can fail <i>in a logical way</i>. Not because of physical stress or mechanical wear, which has all kinds of random noise in the results - but due to a particular sequence of usage. If the two SSDs are mirrored, it is possible that they receive <i>identical</i> usage sequences over their lifetime.<p>... which means they can fail identically - perhaps simultaneously.<p>Nothing fancy or interesting about the solution: all rsync.net storage arrays have boot mirrors that mix either the current generation Intel SSD with the previous generation Intel SSD <i>or</i> mix an Intel SSD with a Samsung SSD.