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

[Hika van den Hoven]

Hoi Johan,

Tuesday, June 3, 2014, 12:56:44 AM, you wrote:

> Thanks for all your comments.



> I appreciate the advice on ZFS, however I’m not running ARC, since
> I was aware of the memory requirements. I do not use ARC,
> compression or deduplication, not enough memory..

> And from reading up (no practical experience) ARC has benefits in
> improving reading data, not so much writing data (which may be my
> bottleneck). I’m just running it in a RAIDZ2-0 configuration, hoping
> for some fault tolerance. Performance was never the goal. That now
> has changed, and I need to review the why and how, guess that is back to the drawing board.

> But memory can be upgraded if that helps the write performance..




> Now it seems this thread has focused on the pro’s and cons of ZFS,
> and I’m a total novice on that subject, hence my very basic
> installation. You have to start learning somehow, somewhere..

> I have learned a lot already here.




> Just to get back to the basic question…

> Processes are killed, I said…Maybe causing a misunderstanding. Some
> processes expected to do real-time data stream processing cannot
> cope with the lack of CPU idle time, mess up and disappear. So maybe
> not to well written for these circumstances. But I need them, so I
> want to split some load over two machines. A master backend (the
> current backend) and a slave backend (a new backend with the receivers).




> My aim was to keep all the data on the master backend, which also
> has the 7TB ZFS Zraid2-0, (raw 12TB in 6 disks) and use that
> processor for the SQL database, master backend comflagging and some
> other services. Using the slave backend only to process and push the
> data up to master backend with the ZFS storage pool. That does not seem to be a recommended option.




> Infiniband looks attractive from performance perspective, but I
> have no idea about cable pricing. I need to cover a distance of
> about 50 meters with lots of bends. 




> From the comments I received so far, it looks like if i have to
> throw $$$ at the problem, it is best spent on a powerful slave
> backend with plenty processing power and local storage. I just miss
> the fault tolerance, unless I just use plain raid mirror.

> Just afraid to drop that system in the garden shed…although it may
> be the safest location for a server, who would steal a server if he can take the lawnmower :-)




> At least I’m encouraged to look again at my ZFS storage, and
> improve that area as well. Time to use google and the ZoL mailing
> list. (If it only for the learning experience, it is still a good exercise to get more familiar)




> thanks again for all your constructive comments!




> Johan


First try to but your post at the bottom of the discussion.

I know nothing about zfs. I have been using simple software raid1 for
years now with lvm2 on top of it. No high memory usage, datasecure and
flexible. You can grow and shrink your volumes at need easily. If you
want higher throughput for myth take two or more separate arrays with
each a myth volume and put them in the same volume group. If you want
even more take a second sata controller and put the two raid drives
from each array on the separate controllers.
Also is your shed dry! You shouldn't put a computer in a possible
moist environment. You will be asking for trouble.



Tot mails,
  Hika                            mailto:hikavdh at gmail.com

"Zonder hoop kun je niet leven
Zonder leven is er geen hoop
Het eeuwige dilemma
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