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

James Abernathy jfabernathy at gmail.com
Thu Jan 24 11:25:03 UTC 2019

On 1/24/19 12:05 AM, Stephen Worthington wrote:
> 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.

Nice analysis. makes sense and supports my plan of replacing as much 
hardware with different hardware. The hardware with the large CRCs that 
you saw the report on was connected via eSATA from the PC to the 
External drive.  that case supports USB, eSATA, and firewire. I'll look 
at what I get with USB for comparison.

I remember at some point in history of having PCs of this generation 
that they had issues with certain SATA 6GBs port and moving back to 3 
Gbs ports on those ports/cables/drives.  I've been hesitating replacing 
motherboards because it means new CPU, memory as well. I'm less and less 
enthusiastic about spending that kind of money when for fun I just built 
a $35 RPI 3 B+ that is a combination FE/BE using LibreELEC 8.95 with TVH 
HTS Server and client. Using a HDHR Connect I could record 2 channels at 
once and watch a recording at the same time.  Hard for me to justify 
another $400 to get the ability to get the 4 channels at once.

I'll try moving some cables and ports around today and see what happens.

Jim A

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