> Are you definately using cables rated for sata III? Have you checked the power connections? Have you checked the power supply voltages durning spin up/later? yeah. the setup is running for years now. as i said: booting from usb stick -> everything works > > > > > > Is there tension or major twisting forces on the sata cables? I've seen this cause intermittent problems and was solved by using a longer cable that reduced the stress at the connector. nope. check and works. > > > > > > Are the drives getting hot (your' model shouldn't have a heat issue under normal conditions). Are the drives bolted into a system? Drives can be sensitive to vibration and identical, unmounted drives will tend to shake each other and can produce rotational torque as well (especially when the same model as they'll all have the same resonances in that case). Either can cause problems with keeping the heads over the track reliably. nope. the issue arised first time after the box was down for several hours. the box is in my cellar so in a good environment. > > > > > I'd definately run all the smart test. start with the conveyance test and then the short self test, and possibly the long test. do check the drive temperatures immediately after each test to make sure they aren't getting too hot. output of the test after my reply. > > > > > > I assume you've done an fsck on the file systems? If not it might be good to check. no i did not. i am running xfs. and the filesystem ist not corrupt. so no repair needed. i can access the data when booting from usb. > > > > > Are you using the mother boards sata interfaces or an add-on card? If using a card i'd check the firmware version on the card and what the manufacturer is offering for updates. motherboard sata. hp microserver gen8 > > > > > Are the drives still under warranty? If so try WD tech support. Also check that all the Raid tools are properly installed with their' dependencies met. could be other hardware/drivers interfering. might reset the bios to "optimized settings". Which software raid package are you using? mdadm has nom dependencies. but i reinstalled the package. version 3.4-14.el7_3.1 > > > > > > Other than that I'd possibly suspect a software problem, not familiar with software raids myself (haven't used on, know what they are). Or possibly a problem with the drive that is intermitant or complex in how it fails. software problem sounds great. i would like to find out, why its not working. i could reinstalled the complete box, but that is not my intension. takes lots of time and i am not learning something new :) regards Andy > > >> >> > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos