[mythtv-users] OT Hardware RAID 5 Recommendations

Tom Lichti tom at redpepperracing.com
Tue Dec 12 19:38:23 UTC 2006


Brian Wood wrote:
> On Dec 12, 2006, at 12:10 PM, George Galt wrote:
> 
>> Brett:
>>
>> Thanks, I'm looking for RAID5 which requires that a parity bit be set
>> across all of the disks.  This requires a fair bit of horsepower.
>> RAID1 is (if I remember correctly) simply a mirror, which would be a
>> waste of disk space.  On that point, I'm not sure if software RAID
>> does level 5.
> 
> It does, assuming it is enabled in the kernel, but it does have a  
> significant overhead, much more than RAID1.

I am running software RAID5 on two machines, my master backend (3 SD 
cards and two HD tuners - HDHomeRun, P4 2.0GHz) and I have not had any 
real performance issues. Once when all 5 tuners were recording, and with 
realtime comm-flagging enabled, there were some IOBOUND errors, but that 
only ever happened once. The other machine is my webserver (P4 2.8GHz) 
which serves a large forum and picture gallery, and it has never shown 
disk performance issues. They are both using IDE drives on internal 
controllers.

Software RAID5 is definitely a viable option.

Tom



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