[mythtv-users] OT-RAID 5 failure. MDADM experts? Seagate 1.5TB failure

David Brodbeck gull at gull.us
Thu Dec 18 18:41:03 UTC 2008


George Mari wrote:
> To each their own.  I have nothing against storage groups, and haven't 
> tried them yet, as RAID5 has been wonderful for me, but that's an 
> awfully general statement regarding "much better performance".  Got any 
> hard data comparing performance of RAID5 and storage groups?  Yeah, 
> yeah, I know - the infamous RAID5 write performance penalty.  Sure, it's 
> there - but for mythtv, or for storing large amounts of media files, who 
> cares?  Write performance is more than good enough for those use case 
> scenarios.
> 

MythTV writes fairly sizable chunks, so I think the RAID 5 write penalty
is probably *mostly* a non-issue -- it hits worst for writes smaller
than one stripe.  If you have your database on the same array, you
*might* potentially run into problems.

There's nothing wrong with RAID 5 for media storage, and it may make
sense if you're using the array for more than just recorded TV.  I just
think that the case for using it on recording drives isn't all that
strong now that storage groups exist.  On the other hand, "I've used it
before, I know how it works, and I like it" is often a perfectly valid
reason to use a technology. :)



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