[edude03]

I am as well (5x 3TB in Raidz1). I'm pretty sure it's because of the likelihood of having an unreadable bit/byte/sector on one of the non failed disks gets higher as the capacity increases and thus there is a good chance that you'll lose some data. This article discusses the theory. http://www.zdnet.com/blog/storage/why-raid-5-stops-working-i...

[anon4]

corrected link: http://www.zdnet.com/blog/storage/why-raid-5-stops-working-i...

[voltagex_]

Is there a way to check statistics of failed read/writes?

[dap]

"zpool status" will show if there have been errors reading data from individual devices. If a drive experiences enough failures, at least on illumos and Solaris-based systems, it will be marked degraded or faulted and removed from service. You can view individual failures on these systems with "fmdump -e". Here's a made-up worked example: https://blogs.oracle.com/bobn/entry/zfs_and_fma_two_great