[mythtv-users] Slow video on XFS raid 0, ok video on ext3 on single drive.

[Brian Wood]

On Jan 1, 2007, at 12:32 PM, devsk wrote:

> >> First, for whatever reason, /dev/md0 does not seem to be my RAID  
> device.
>
> oh boy! you need to know which RAID you are using. software raid  
> provided by linux (MD type) or BIOS raid provided by linux driver  
> device mapper (DM type)? MD type will give you /dev/md0 and DM type  
> will give you /dev/mapper/<blah>. It looks like you are using  
> dmraid and /dev/md0 is a bogus device on your machine (did you  
> mknod it or are there 'fd' type partitions on your disks, which  
> kernel detected automatically). You should do 'fdisk -l /dev/mapper/ 
> sil_agbgdgbjfhei' and chose appropriate partition to mount for your

Plus you mention a "RAID card" and also a couple of different  
software RAID methods, which would seem to be a contradiction. A true  
RAID card would simply appear as a single drive, but you'd know if  
you had one - you would have paid through the nose :-)

So-called "raid cards" or motherboard RAID capability is really just  
a bit of BIOS memory to store some setup data for proprietary  
(Windows) software RAID drivers. It's mostly marketing, not  
engineering, and of little or no interest to Linux users.

Your drive numbers for c,e,f and g are not *that* bad, but the ones  
for a and b really stink. Are you sure you're using an 80-conductor  
cable?

You might also want to look into bonnie or something like it to get a  
more true picture of your actual filesystem performance.