[mythtv-users] Some master/slave backend advise required

[jacek burghardt]

How about just getting couple of those ?
http://www.elgato.com/en/eyetv/eyetv-netstream-4sat


On Mon, Jun 2, 2014 at 3:08 PM, Raymond Wagner <raymond at wagnerrp.com> wrote:

>
> On Jun 2, 2014, at 16:55, James Bailey <paradoxbound at gmail.com> wrote:
>
> Hello 4GB is the minimum spec for ZFS then you should add more for MythTV,
> I ran 16GB on my backend with ZFS on Linux and had no problems. You want to
> limit your ARC to no more than 50% of RAM. If you are mainly writing SSDs
> are not going to help unless you use a couple of smaller ones for the ZIL
> because your ZIL is killing your IOPs. you need to mirror these because if
> you lose a separate ZIL Drive your ZFS array is fscked. As always you
> should pair ZFS with ECC RAM. don't bother with depude unless your workload
> really suits it as it will kill disk performance.
>
> If you haven't been there already talk to the people on the ZoL mailing
> list they are very knowledgeable and quite friendly if you ask your
> question right. You will get lots of tuning advise from them for your work
> load.
>
> If you end up splitting your storage from your backend, consider a couple
> of cheap Infiband cards from Ebay crazy bandwidth 10Gbit ethernet emulation
> or 20Gbit native.
>
> Some of the new Intel Avonton storage boards are a reasonable price and
> you can stick up to 32GB of ECC ram on them.
>
> Jim
>
>
> On 2 June 2014 19:59, Johan Van der Kolk <johan.vanderkolk at gmail.com>
> wrote:
>
>> Hi,
>>
>> I’m running myth 0.27 (v0.27.1-7-g41d04b6) on Ubuntu server 14.04 with an
>> i5(3GHz) and 4GB memory. I’m using 4 DVB-S2 tuners as source.
>> Due to relocation of the dish I have to install a slave backend. I can’t
>> (don’t want to) move my server to the garden shed.
>>
>> I have found that recording about 8-10 HD channels simultaneously will
>> start killing processes on the backend (not the myth processes though), but
>> the CPU load of the DVB-s2 stuff by itself requires 100% cpu.
>> Mythcommflagging did not help either, although I could limit the
>> simultaneous jobs to get more breathing space.
>> So my thought was to solve both problems at the same time with a new
>> slave backend, where the dvb-s2 stuff is running, by itself. Storage and
>> commflagging still to be done on the master backend (which has 8TB of ZFS
>> storage)
>>
>> I can see two issues now:
>> Bandwidth: When recording 10 channels (what I want to achieve), I
>> estimate worst case (based on what i recorded so far) 3GB per channel per
>> hour, or 833Mb/s one way traffic, without other overhead. And not watching
>> anything...
>> How to solve this, and does myth traffic between master and slave benefit
>> from Jumbo Frames. I could use two network cards in each machine, and
>> create a 2 x1 Gb trunk between the switches.
>> Second part of the problem might be that the ZFS file storage is not fast
>> enough. (upgrade to SSD maybe)
>>
>> Configuration:
>> Is it possible to configure mythtv in such a way that it does what I
>> want, or are there better ways to do this?
>>
>> Any help appreciated!
>>
>> Johan
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>
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