[mythtv-users] Yet another question about data storage

[Johan]

On 11/24/2010 01:43 PM, Greg Oliver wrote:
>
> I use an external HW raid enclosure attached via esata to my master 
> backend.  The next array I spend I will definitely spend the extra 
> $150 and get a unit with a configurable stripe size.  This one is set 
> at an unconfigurable 256k.  While all of my media and virtual machine 
> volume groups are configured with 4MB inode spacing, it could be quite 
> a bit faster if I could tweak the array settings as well.  This unit 
> also only allows (1) array to be configured.
>
> All in all, I am pleased with the price/performance though.  With 
> newegg having $70 2TB drives today, I may just get another early x-mas 
> present  :)

x-mas is always a good excuse for a system upgrade :)

That's good remark about the striping size, never thought of that. I'll 
check if my old motherboard has that luxury...

In my scenario, I can record several streams at once (with about 7~8 
recordings and some commflagging the CPU is at 100% and things start to 
break) but only watch one at a time. Commflagging might do some more 
reading but does not require any realtime priority. It looks like write 
performance is the key for me.

If I can add 2 two TB disks to the internal RAID controller, I may get 
even better performance, as each disk will have its own SATA channel.

Is it usefull to match the stripe size and other parameters (such as the 
hdparm readahead value, which determines how many sectors are read at 
once by the OS)?

There are probably nice tools available that do all that benchmarking...



Johan