[mythtv-users] Disk Arrangement and LVM + JFS

[Ben Curtis]

> I've also found that the software raid5 was noticably slower on my setup
> (even with an Athlon 64 X2 4800+ and 2GB DDR2 800 DC ram) - perhaps
that's
> because I have 5 tuners and have very little 'idle' time -- sometimes
even
> all 5 tuners recording at once. (and probably contributing to the dual
> hardware failures due to high write utilization) -- For example, since I
> re-built my system 8 months ago - the MythWeb "Recording Statistics" page
> shows a "Percent of time spent recording" of 93% !!
> 

I understand your point, but I'm definitely going to use RAID5 for video
storage.  Performance isn't as much of an issue there as reliability,
however performance on the system drives I do care about, which is why I'm
considering RAID0 there.

> Increasing the
> default stripe cache size can be a huge benefit here.
> something like (for md1):
> echo 2048 > /sys/block/md1/md/stripe_cache_size
> to see if the stripe cache is being overrun check the
> /sys/block/md1/md/stripe_cache_active
> and see if it is being maxed out. 
> 

Interesting.. Is it odd that all my arrays have 0 set for
stripe_cache_active?  stripe_cache_size is also only set to 256.