[mythtv-users] Hardware Setup Advice

[Steven Adeff]

On Wed, May 23, 2012 at 11:41 AM, David Crawford
<davidcrawford83 at gmail.com> wrote:
> On 23 May 2012 15:30, Andre <mythtv-list at dinkum.org.uk> wrote:
>> On 23 May 2012, at 14:53, Simon Hobson wrote:
>> > David Crawford wrote:
>> >> However I'm sure there will be problems down the line as I have another
>> >> PC setup with windows software with the same hardware and it encounters
>> >> problems also when recordng many streams.
>> >
>> > Your biggest issue will be disk seek times. Essentially, if you are
>> > recording 18 streams, then you have 18 threads which are syncing a file to
>> > disk once a second. This means the disk will be trying to do 18 seeks &
>> > writes/second - and a cursory look at the specs of most disks will reveal
>> > that this is likely to lead to a bottleneck.
>> > It's not the basic data rate that's the issue, it's the quantity of
>> > seeks that kills performance.
>>
>> David I also find that in general AV specific drives work much better than
>> generic consumer drives, I have many WD AV-GP and Seagate Pipeline drives. I
>> find I am able to record 19 simultaneous HD streams across 5 disks without
>> expensive hardware.
>>
>> I also use MythTV in a broadcast environment, feel free to contact me off
>> list if you think that would be useful.
>>
>> Andre
>>
>>
>>
>> >
>> > Adding additional disks, each in a separate storage group, will spread
>> > the I/O load across multiple drives and you should have a lot less of a
>> > problem.
>> > Eg, if you add two more drives, then you'll end up with around 6
>> > streams/drive - if you can "about manage" now on 18, then around 6 should be
>> > no problem. Even a second drive should help.
>> >
>> > As for using a NAS, it depends very much on it's performance. Remaining
>> > polite, some NAS boxes "perform poorly", and it also varies with access
>> > method (SMB vs NFS vs AFP vs ...).
>> >
>
> Thanks a lot for the info..
>
> I'm using a seagate blackarmor NAS 110 at the moment. It actually works
> pretty well and has been for some time, but i guess i could do with another
> drive or 2 since i have 2 systems and I'm actually thinking of using the
> other as a secondary backend if i can mythtv working stable enough.
>
> So my thinking right now is:
> OS and database on SSD (is this a must?),
> add another internal HDD like seagate pipeline or constellation 2,
> split storage between the 2 HDD's and the NAS.
>
> What about transfering the files over to the NAS's to free more space on the
> local HDD's? Would that be preferable you think?
>
> David

please don't top post.

> OS and database on SSD (is this a must?),
no, but it is definitely nice. I have my OS and DB on a 80GB SATA
drive and have never had an issue with speed. the more tuners,
frontends, commflagging, and transcode jobs you do the more you tax
your DB access. an SSD will basically eliminate any issues on larger
systems.
plus they're fairly cheap now.

as for storage. local is always nice because of speed. with storage
groups you can move recordings around, but right now there's no way to
tell Myth "record to these drives, but move older recordings to these
drives", but you can do it manually, just make sure the user
permissions on your "archive" drives doesn't allow the user running
Myth to write to the drive. it's not perfect, but possible. or you can
just let Myth decide what drive to record to and give it access to
drives anywhere on your system.

I personally have six 500GB recording drives that I've been running
for about 4yrs now, on my backend, then on a fileserver, I have five
2TB drives that all my media, etc go on, and I can archive recordings
there later, though I do so manually.

-- 
Steve
http://www.mythtv.org/wiki/User:Steveadeff
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