[mythtv-users] LVM & Disk Performance

[Harley Peters]

Olivier wrote:
> Hi,
>  
> I just installed a second hard drive into my mythtv box and I following 
> the recommendation of using LVM partition. What I did not expect is that 
> my tv quality would get affected.
>  
> Before I installed this drive, I had a older 20G drive (5000 rpm I 
> believe) drive with default partition from rh9 install and everything 
> was ok.
>  
> I then installed a 80G drive, with LVM partion, and as soon as I tell 
> mythtv to store ringbuffer on this on, the tv playback start to become 
> choppy with small ~300ms pause every 2 second or so.
>  
> I don't understand; I though this drive was slightly faster, and I did 
> not think LVM was slower... Maybe I did something wrong with the LVM 
> partition: this is pretty new stuff to me.
>  
> Here is what I did:
>  
> fdisk /dev/hdb
> // create a single partition of type 8e (LVM)
> n p 1 ret ret t 8e p w
> reboot
> pvcreate /dev/hdb1
> vgcreate -s 64m vg0 /dev/hdb1
> vgdisplay -v
> lvcreate --n localdisk --size 76.25G vg0
> mkfs.ext3 -T largefile4 -m 0 /dev/vg0/localdisk
> mount /dev/vg0/localdisk /localdisk
> Help much appreciated;
>  
> Cheers,
> Olivier.
>  
> 
> 
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More than likely you don't have dma turned on on your 80G drive.

Harley