[mythtv-users] RAID BTDT's

chris at cpr.homelinux.net chris at cpr.homelinux.net
Sun Apr 2 09:04:54 UTC 2006

On Sat, Apr 01, 2006 at 11:22:16PM +1100, Support [ Ian Ward ] wrote:
> Anyone who has a large raid-5 array happy with the performance?  I have 
> to look into it, but can transcode be set to use a different disk for 
> it's temporary files ( perhaps a ramdisk for /tmp ) ?

"Large" is in the eye of the beholder.

I'm running with three 160Gb drives.  They were partitioned so that 
hda1 and hdc1 impliment a small RAID-1 (mirrored) /boot partition with
LILO installed on both MBRs (so that I can just swap the cables if 
hda dies and the system will still boot), hda2, hdc2 and hde1 provide 
swap, and hda3, hdc3 and hde2 make up a RAID-5 root partition (which 
holds *everything*).  I'm running on a 2.8GHz CPU and have 1Gb of RAM 
and the overhead attributable to software RAID is negligible.  The 
only real issue I ever had to face was a problem with IRQ assignments 
for my PCI IDE card for the third drive.  My BIOS insisted on giving 
it the same IRQ as my ethernet card, so it would run just fine until 
I started a playback on a remote machine, at which time the IDE card 
would drop interrupts and panic the kernel.  I solved that problem, 
and now the system is rock solid.

If Myth was capable of spreading the recordings among multiple 
directories then I would probably have used RAID-5 for a much smaller 
root partition and used the remaining space on all three drives as 
separate non-redundant storage.  The concern there is simply 
capacity, not performance.

"When fascism comes to America, it will be wrapped in the flag and 
carrying the cross." - Sinclair Lewis (1935)

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