On 09/14/2014 02:06 AM, Dan Ritter wrote: > On Thu, Sep 11, 2014 at 06:17:00PM +0200, Linux-Fan wrote: [...] >> Is there any means to configure MDADM (or such) to make sure that all >> devices are recognized before attempting to start the array so that I >> could manually reconnect the missing disk and then start the array >> without any resync? >> >> If not, might it be a good idea to write a script to check if the >> devices are available and only then enable that RAID? >> >> I want to avoid doing superflous resyncs as this always takes a lot of >> time and seems to be an unnecessary load for the drives. > > What's actually happening here is that mdadm is rejecting one or > the other disk because of a problem reading or writing to that. > > It's almost certainly a real problem, and in my experience it is > not the disk itself which is bad, but something in the path (the > USB port, the USB cable, the USB-SATA interface) or the power > supply for the disk. It might be the USB 3.0 controller -- it is a 03:00.0 USB controller: Renesas Technology Corp. uPD720201 USB 3.0 Host Controller (rev 03) which is on a PCIe Card. Still, it is the only USB 3.0 controller which I could get to work without Kernel Oops and the only one to normally get a stable USB 3.0 connection. > You will continue to have these problems if you persist in doing > this, up until the day that one disk actually fails. Time to do > something else. If you can change to ESATA or invest in a SAS > controller and external SAS multi-disk chassis, you can get > reliable data storage again. Neither the computer, nor the disks do have ESATA unfortunately and investing in SAS -- while being reliable -- is too expensive at the moment. Also, the reliability of the external storage is required to be perfect -- it is mainly designed to be a storage for various media which could be collected from other sources but would be tedious to find again and is therefore better stored locally. Also, I am going to store a few VMs, but these are also mainly used for testing purposes. > In the meantime, you can: > - add a bitmap file to the RAID, which will speed up rebuilds. > - use the --no-degraded flag, to prevent assembly of a RAID that > is lacking a disk. Thank you very much for these hints. I am going to try both. Linux-Fan -- http://masysma.lima-city.de/
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