[mythtv-users] Storage Group Disk Scheduler

[Dave Stuart]

________________________________
From: Raymond Wagner <raymond at wagnerrp.com>
To: Discussion about MythTV <mythtv-users at mythtv.org>
Sent: Sat, July 9, 2011 3:12:22 PM
Subject: Re: [mythtv-users] Storage Group Disk Scheduler

On 7/9/2011 17:21, Dave Stuart wrote: 
I have a backend that I am running on a low memory system.            I have 
mounted 7 filesystems on 2 hard drives.  The filesystems have to be small enough 
to let fsck work without           running out of memory.  The scheduler seems 
to think that each           of the 7 mounts is on a different physical disk, 
and therefore           the disk I/O scheduler option is not working correctly.  
Is           there any way to make this work?
>
Switch to a filesystem that uses journaling to prevent lengthy fscks, and allows 
for single partitions.  Switch to a filesystem     whose fsck application is not 
so memory intensive, and allows for     single partitions.  Stop uncleanly 
unmounting partitions, such that     lengthy fscks are no longer necessary.  Buy 
more memory for your     MythTV system, or failing that, buy a new MythTV system 
such that     you can buy more memory for it

Could you give a bit more detail about this system with insufficient     memory 
to run fsck?  I had no trouble running a fsck on a 2TB EXT3     partition 
earlier this week using my laptop.  My laptop still has     the same 384MB of 
memory it shipped with when I bought it over 10     years ago.


Thank you for your reply.

The device that I am using to run the backend is a goflex net using the plugapps 
instructions.  It has 128mb of ram.  I have a 1tb drive and a 1.5tb drive that I 
am using to store shows.  I did try at one time to run a fsck on the 1tb drive 
and it had not finished after 3 hours.

I am using ext3 filesystem (journaling), but I want to be able to use fsck as a 
backup.

I am not uncleanly unmounting partitions. 

More memory is not an option for this machine, and this is the machine that I 
will be using.

Can you recommend a filesystem that would be better to use for this 
application?  Should I specify format parameters to make the fsck use less 
memory?

In any case, it seems to me that the mythtv scheduler should be using the device 
rather than the filesystem to determine the 'weight'.  I can imagine a number of 
scenarios when using storage groups where this would be a good idea.

Thanks

dave
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