[mythtv-users] RAID 1 mirror with mythtv backend???

Stephen Worthington stephen_agent at jsw.gen.nz
Thu Jan 24 05:05:47 UTC 2019

On Wed, 23 Jan 2019 17:44:36 -0500, you wrote:

>On 1/23/19 11:42 AM, Will Dormann wrote:
>> On 1/23/19 11:31 AM, James Abernathy wrote:
>>> But lately I've started to have a mdadm failure about every 2-3 weeks.
>> This is not acceptable.
>>> were Toshiba P300 desktop drives.  Once I remove the drive I ran
>>> Spinrite 6 on them that reads and writes every sector on the drive.  It
>>> found no errors.
>> No need for that snake oil.
>>> What are the opinions on using RAID mirrors for mythtv recordings. Does
>>> that cause more problems than it's worth??
>> RAID should not cause problems.  Its goal is to minimize downtime in the
>> case of the inevitable hardware failure.  It can also prevent data loss
>> if you put all of your eggs in one basket of a single drive and do not
>> have backups for some reason.
>> If you have a drive that you're wondering whether it's good or not, post
>> the SMART output for that drive.   e.g.:
>> sudo smartctl -a /dev/sda
>One of the drives I pulled out and that tested good I put into a USB 
>external drive to use for temporary backup. I was using it today to 
>backup my RAID mirrors offline and I get an email from smartctl daemon.
>The following warning/error was logged by the smartd daemon:
>Device: /dev/sdf [SAT], ATA error count increased from 0 to 813
>Device info:
>TOSHIBA HDWD120, S/N:58NYHDVCS, WWN:5-000039-fd4db8021, FW:MX4OACF0, 2.00 TB
>I ran a smartctl -t short test and I attached the output as a log file.
>Jim A

Those are CRC errors, and in a large quantity like that they are
normally indicative of a bad SATA cable (or one that is not firmly
plugged on).  Or possibly a USB cable problem in this case.  Dirty
connectors will also show up like this, and having the cat tread on
the cable can also do it.

If the cable is OK, then the next most likely candidate for the cause
is a bad SATA port.  SATA ports do occasionally die, and as they are
normally in pairs on the controller chip, you normally get two ports
with the same problem.  So trying again on a SATA port on a different
PC, or a port that is not on the same pair is best.  In the case of a
USB enclosure, the SATA to USB converter chip in the enclosure becomes
the suspect if changing the USB cable and port does not fix it.

It the fault follows the drive when you move it to a different SATA
port on a different cable, then it is likely to be the drive
electronics that are failing, and you need to get a new drive.

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