[mythtv-users] Storing recordings on a NAS via NFS (I/O concerns)

[Jason But]

>> Therealways seems to be people querying recording rates, yet I have never seen problems. My current install has Myth running on the same physical box as my 6-disk RAID-5 array and I have never seen any problems with up to 7 concurrent recordings, two concurrent playbacks, while the same box is also my home network gateway, file server, DNS server, print server, everything else server. While the computer is an i5 and not a cheap NAS, the disks are surely not going to be a problem...
>>
>> Jason
>>
>>
>> -- 
>>
>> ----------
> I understood the query to relate to network I/O. Having your disk on the same machine as the backend will result in completely different writing and buffering characteristics compared with an NFS mount which, for example may not have any buffering and may just drop packets during transient congestion spikes. As I understand it at least.
>
> In your situation I would expect substantial stuttering of the playback before the loss of any recording information. Recording to a NFS mount might result in recording loss before playback stuttering is even visible.
I agree, however as previously mentioned, a gigabit network can easily cope 
with digital video bit rates which arenot high, perhaps an NFS mount may be 
an issue for 3 or 4 concurrent recordings/playbacks but it should cope with 
most scenarios. Also, given that networks nowadays are typically switched, 
as long as there is no router with queuing in the path, you should not see 
much delay variation to impact playback and recording. I think the main 
impact is more likely to be the CPU performance of the (typically ARM) 
processor on the NAS, unless you are overloading the NAS with work to do, I 
would expect it to survive a simple/low recording/playback environment

I think the same applies when people suggest putting the DB on another 
spindle. I have not bothered to do so, and as I stated, my box performs many 
tasks and has never skipped a beat even with a half dozen recordings and two 
playbacks