[mythtv-users] thoughts on a combined backend/NAS box?

[Joseph Fry]

On Tue, Jul 16, 2013 at 10:06 AM, Jim Oltman <jim.oltman at gmail.com> wrote:

> On Tue, Jul 16, 2013 at 3:37 AM, Tim Draper <veehexx at gmail.com> wrote:
>
>> On 16 July 2013 06:55, GZ <gzornetzer.lists at gmail.com> wrote:
>> > Hi all,
>> > I've been thinking about upgrading my mythtv setup and at the same time,
>> > I've also been looking at buying a RAID5 NAS box.  After looking at the
>> > price tags on some of those enclosures, I'm thinking about just
>> building a
>> > combination RAID / mythbackend box.  I've read some of the guidance on
>> the
>> > wiki, indicating that RAID really isn't the best way to go for the
>> mythtv
>> > recording drive.  I'm thinking about the following drive setup:
>> >
>> > 1 SSD for the OS/database
>> > 1x 1 tb for active recording (my existing recordings drive.
>>  Eventually, I
>> > may just upgrade this to a 3tb drive that would act something like an
>> in-use
>> > hot spare
>> > 4x 3tb drives in RAID5 for archive storage (pictures / long-term video
>> > archive)
>> >
>> > Since all of my tuners are now external (HDHR prime & usb QAM), I'm
>> thinking
>> > about a microitx motherboard to keep this box smallish (corner of my
>> > office).  There are a few H77 boards with 6 total SATA ports an H87
>> board
>> > with 6x 6gbps sata.  I figure that a 4-core ivy bridge or haswell
>> process
>> > has plenty of juice for this.
>> >
>> > Couple of things that I'd like to do:
>> > - It would be cool to move shows from the recording drive to the archive
>> > upon lossless transcode.  Do I have to write custom transcode rules to
>> do
>> > this?
>> >
>> > - I'd like to use ACPI wakeup to reduce power usage on this system.
>>  This
>> > means that I'm going to need some way to lock mythbackend when I want
>> to use
>> > the NAS functionality.  I suppose that I could run some mythfrontends
>> on the
>> > client, but that's pretty kludgy.  How complex is it to code up a client
>> > that connects to mythbackend enough to bump the usage count and block
>> > shutdown?  Alternatively, does anyone have a good way to trigger a
>> > mythwelcome lock and unlock commands remotely over the network?
>> >
>> > Any advice or thoughts are welcomed.
>> > Thanks very much,
>> > -Greg
>>
>
> I'll just put out there that no one in their right mind should ever use
> RAID5.  It's just not safe.  I'd recommend at least RAID6 or possibly
> RAID10 if you're paranoid.  Remember, if a disk fails in RAID5, you need to
> resilver the array.  That can take time.  What if another disk were to die
> during the resilver?  You'd be screwed.  And don't think it won't happen to
> you.  It happened to me.  It was awful.  Luckily, I managed to grab most of
> my data.
>

There is nothing wrong with RAID 5... but you have to be aware that it
cannot be used in place of a backup, just like any RAID solution.  The odds
of a two disk failure are far lower than a single disk... so while the
potential is there, odds are it won't happen and in the meantime your
system will keep chugging along while the array rebuilds.

Of course I prefer a raid 1 or 10 array for performance, redundancy, and
ease of recovery, if your willing to sacrifice 50% disk space required.

I use software raid 1 across 3 drives for my OS, database, and most
critical data....  I only RAIDed a small partition at the start of my 3
recording drives, the rest of the drives are JBOD.  So if I lose 2 drives,
I can still recover my system easily, but I lose recordings.


>
> That being said, I have an ESXi host that has 24 GB of RAM, a FreeNAS VM
> with PCI Passthrough of 6 500GB SATA drives, and 2 2TB SAS drives.  FreeNAS
> serves out an CIFS/NFS shares.  I've never had an issue with the RAIDZ2 or
> Mirror I'm running.
>
> Another VM is MythBackend dedicated and the third is an Ubuntu server
> install for my Subsonic server.  (There have been numerous discussions this
> past week on the value of straight up virtualization versus chroot.  I
> won't get into it as I have a solution that works well for me.)  I really
> like this setup.  However, since I have my NAS as a VM, and all clients on
> my network require the NAS, the ESXi host is on all the time (along with
> the APC SmartUPS 1500XL the host and 24 pt gig switch/pfSense Atom box/HD
> HomeRun/AP/Cisco ASA are all connected to).  I've come to terms with the
> electricity bills.
>
> The only real issues I've run into are Ubuntu based ones.  For some
> reason, I had unmet dependency troubles with the kernel image and header
> files ont the virtualized machines.  I'm thinking I did something wrong,
> but I've only ever tried to do the standard apt-get update/dist-upgrade.
>
> Anyway, I'd virtualize if I were you.  Just my experience and 2 cents (or
> pence, or whatever your local currency).
>

Virtualization adds an unnecessary layer of complexity and another point of
potential failure.  If all he wants to use the system for is mythtv and
file sharing, then I can't see why you would recommend virtualization...
you gain nothing over running the system natively.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.mythtv.org/pipermail/mythtv-users/attachments/20130716/9f232c75/attachment.html>