[mythtv-users] Storing recordings on network share

Michael Watson michael at thewatsonfamily.id.au
Sun Sep 25 10:38:31 UTC 2011


On 25/09/2011 19:49, sususu wrote:
> im using XFS and though i have to admit i sometimes(random once a 2 
> months on my "big" system)  have a uncleared recorder failure
> especially recording 4(sometimes more) programs in parallel at  maybe 
> 3 MBit/s per stream works fine with allocsize 512MB and a cheap segate 
> 1TB
> (also with the system on the same disk but different partition and 
> using almost no swap with 2GB RAM)
>
> however i also use NFS to give the old system the possibility to 
> access the recordings of the big system too.
> though i don't record through it a major performance drop even when 
> reading can be viewed and even expanding the NFS buffering does not 
> get rid of it completely
> when working with NFS one can see that accessing files only partially 
> and not reading through causes some stuttering too as with many small 
> files
> this would either call for a "temporary file" (Buffer) stored locally 
> and feed through the NFS in a constant stream or use of a different 
> networkFF (both some options i have not evaluated yet completely)
>
> ------------------------------------------------------------------------
> *Von:* Gary Buhrmaster <gary.buhrmaster at gmail.com>
> *An:* Discussion about MythTV <mythtv-users at mythtv.org>
> *Gesendet:* 20:02 Samstag, 24.September 2011
> *Betreff:* Re: [mythtv-users] Storing recordings on network share
>
> On Sat, Sep 24, 2011 at 10:37, belcampo <belcampo at zonnet.nl 
> <mailto:belcampo at zonnet.nl>> wrote:
> ....
> > If you use xfs with with allocsize=1024M, one can easy avoid most of the
> > randomness of videofile-writes and thereby avoiding allmost if not all
> > of the mentioned troubles.
>
> Yes, and no.  Using any extent based file system will reduce the
> file fragmentation (which is generally a good thing), and reduce
> the ongoing allocation overheads (also a good thing).  But if you have
> multiple files open for writing, you will still be seeking from one file
> extent to another as each files chunks are written.  As always, your
> particular usage and results will vary.
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>
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My system consists of all P4 3.2Ghz Systems, all 2Gb RAM, GigaBit Ethernet

MBE has a single DVB-T Tuner, and 8 SATA Hard Drives, one is OS / DB 
Drive, rest are Myth Recording / Video Drives.   Provides All Data 
drives run XFS, allocsize=64M.
SBE / Frontend - Network Boots, 2x PCI DVB-T Tuners
SBE - Network Boots, 1x PCI DVB-T Tuner
(Plus another 2x FE, network booting.)

Hard drives in the MBE, range from 400Gb to 1TB, including Hitachi, 
Seagate, Samsung and WD

It is not uncommon for system to be recording 4+ Streams, (its currently 
recording six streams, four of which are writing to MBE via NFSv4.)
We rarely see any disturbance in the recordings, or any stuttering 
during playback.  The only time we have problems with recordings is when 
it is windy, and the aerial is getting blown around (wobbling in the wind).

Although most of the hard drives are SATA2, all of the interface they 
are connected to are SATA1.

Total Disk Space:
Total Space: 3,052,171 MB

  *
      o Space Used: 2,997,692 MB
      o Space Free: 54,479 MB
      o Space Available After Auto-expire: 1,918,212 MB
          + Space Used by LiveTV: 1,429 MB
          + Space Used by Deleted Recordings: 76,314 MB
          + Space Used by Auto-expirable Recordings: 1,785,990 MB


+----+-------------+----------+------------------------------+
| id | groupname   | hostname | dirname                      |
+----+-------------+----------+------------------------------+
|  1 | Default     | nas01    | /data/nas01/sdb/recordings/  |
|  2 | Default     | nas01    | /data/nas01/sdd/recordings/  |
|  3 | Videos      | nas01    | /data/nas01/sdg/videos/      |
|  4 | Trailers    | nas01    | /data/nas01/sdg/trailers/    |
|  5 | DB Backups  | nas01    | /data/nas01/sdc/dbbackups/   |
|  6 | Coverart    | nas01    | /data/nas01/sdg/coverart/    |
|  7 | Fanart      | nas01    | /data/nas01/sdg/fanart/      |
|  8 | LiveTV      | nas01    | /data/nas01/sdg/livetv/      |
|  9 | Default     | nas01    | /data/nas01/sda/recordings/  |
| 10 | Banners     | nas01    | /data/nas01/sdg/banners/     |
| 11 | Screenshots | nas01    | /data/nas01/sdg/screenshots/ |
| 12 | Default     | nas01    | /data/nas01/sdf/recordings/  |
| 13 | Default     | nas01    | /data/nas01/sdg/recordings/  |
| 14 | Default     | nas01    | /data/nas01/sdc/recordings/  |
| 15 | Default     | nas01    | /data/nas01/sde/recordings/  |
+----+-------------+----------+------------------------------+



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