[mythtv-users] understanding storage group balancing

[Jim Abernathy]

On 8/6/20 12:28 PM, Bill Meek wrote:
> On 8/6/20 11:07 AM, Jim Abernathy wrote:
>> I've been observing that no recordings are being written to one of my 
>> directories in my Storage Group - Default.  I have 2 directories 
>> defined but only one has any files in it. The volume that is getting 
>> all the recordings has about 300GB of free space more than the other 
>> volume.
>>
>> df -h shows:
>>
>> /dev/md1        1.8T  402G  1.4T  24% /mnt/md1
>> /dev/md0        1.8T  702G  1.1T  41% /mnt/md0
>>
>> jim at mythbuntu:~$ ls /mnt/md1/recorded-tv2/
>> 10404_20200806103000.ts      11701_20200806110000.ts
>> 10404_20200806103000.ts.png  11701_20200806110000.ts.png
>> jim at mythbuntu:~$ ls /mnt/md0/recorded-tv1/
>> lost+found
>> jim at mythbuntu:~$
>>
>> So my question: is mythtv using the storage group directory that is 
>> on the volume with the most free disk space?
>
> Check which "Storage Group Disk Scheduler" is in use.
>
> You probably want "Balanced Free Space" 'til the 2nd disk fills.
>
> Then switch to your preferred scheduler, e.g."Balanced Disk I/O"
>
> Ref: 
> https://www.mythtv.org/wiki/Setup_Storage_Directories#Storage_Group_Disk_Scheduler
>
>> I was kind of hoping that it would use the 2 directories on different 
>> volumes to balance the writes for multiple recordings at the same time.
>
> It can.
>
> -- 
> Bill


So I have the default disk scheduler of "Balanced Free Space". That 
explains the problem.  Since the backend is also a NAS for the home, I 
just remembered I run Macrium Reflect to put backup images files on the 
NAS and that was going to only one of the volumes.  So it was growing 
outside of Mythtv and it was trying to balance by putting recordings on 
the other one.

I think I want to get it balanced first and then change to "Balanced 
Disk I/O". Since the disk I'm using are four 2TB drives in two RAID-1 
mirrors on a 3Gb/s SATA interface, balanced I/O might be better.

I should probably move the Macrium Reflect image backups to a new USB3.1 
external case I have with a Samsung EV0 970 NVMe m2-2280 SSD in it. It 
does the backup averaging over 1.4Gb/s; way higher than a Gbit enet 
connection to the NAS; 10 minutes vs. 30 minutes.

Jim A