[mythtv-users] What is best filesystem for recordings?

[Tom Bishop]

On Tue, Jun 30, 2015 at 7:20 AM, Andre Newman <mythtv-list at dinkum.org.uk>
wrote:

>
> On 30 Jun 2015, at 09:47, Warpme <warpme at o2.pl> wrote:
>
> > Hi *
> >
> > I just got some free space on my server (8T Seagate Archive for videos)
> which temporarily gives me spare capacity allowing change filesystem for
> recordings volumes.
>
> I’m interested in how you get on with the Archive drive, shingled tracks I
> believe? Not happy about buying a Seagate (ever again) but HGST start to
> launch some shingled archive drives too. I have 4x4TB and 2x6TB for media
> archives, work media not just movie rips, ok a lot are movie rips, will be
> needing some more space soon.
>
> >
> > Currently I have 2x4T HDD allocated purely for recordings. Both volumes
> are now on ext3.
> >
> > After years of relaying on ext3 I think it is not best filesystem for
> recordings as:
> > -delete is very throughput expensive
> > -chkdsk is really long
> > -starting loosless cut makes hell of:
> > TFW(/myth/tv/21101_20150630054000.ts:67): write(57152) cnt 35 total
> 2079656 -- took a long time, 2571 ms
> >
> > So what FS will be better: XFS or JFS or …?
>
> I always use ext4 for videos and xfs for recordings, concurrency seems
> better in xfs than ext4, I remember that cpu load was higher but corruption
> due to lost dvb packets was much lower.
>
> A much bigger effect I have seen for recordings drives is switching to AV
> drives, WD AV-GP, Seagate Pipeline or Hitachi Cinema. I have run tests with
> 19 simultaneous HD recordings spread across four WD AV-GP 3TB drives with
> no visible dvb packet loss, 24 simultaneous was a big mess! The AV drives
> seem to seek a lot less than regular desktop drives under the same load.
>
>
> >
> > I think following criteria should be compared:
> > 1.concurrency (frequently I have 8-10 concurrent HD recordings);
> This is a lot of simultaneous HD for only two drives! I usually think 4
> per drive is absolute max, pref  3.
>
> I am recording 6 HD channels simultaneously+ overlaps on to one XFS 4TB
> Seagate Pipeline drive for an experiment, there are dropouts around
> overlaps and sometimes in programmes but this is not using MythTV, I think
> Myth is much more demanding on drive and FS performance. This drive is
> always full due to the permanent recordings (6pm to 1am every day) so a
> delete oldest job runs to clear space, I don’t think this would be possible
> with ext4 or 3.
>
> > 2.CPU consumption under high FS load;
> I see xfs being higher than ext4 but it seems to cause less packets drops
> from my tuner cards, the HVR4000’s lose interrupts easily when CPU load is
> high, lost ints= lost dvb packets.
>
> > 3.reliability (I don't have UPS and sometimes power is lost when many
> recordings are ongoing);
> I have a UPS but I have also pulled the wrong drive from the hot swap
> array! The XFS tools are different so you must learn them but I have found
> them able to recover from many external problems, hot swap mistakes, kernel
> AHCI driver problems, bad cables, failed fans.
> > 4.stability/maturity (i.e. recovery from bad/deep FS corruption);
> As above, learn the tools, ask the mailing lists but it’s worked well for
> me for many years.
>
> > 5.any other I forgot..
>
> A friend runs a simultaneous recorder system (he uses MythTV for this)
> where he records all the main UK DVBT channels HD & SD from seven tuners on
> to six harddrives, he says ext4 is useless for this but xfs works fine. His
> system is expiring and deleting files during recordings all the time, he
> had problems with four drives, upgraded to five, then added the UK HD
> channels and added a sixth drive.
>
> Andre
>
>


Good information, I will throw my .02, I've been using xfs for years have
used JSF riserFS and many others but from testing and with RHEL 7
defaulting to xfs, I pretty much only use XFS for storage/data drives.  I
will leave my OS drives running ext4 but thats about it.  I think XFS has
gotten a lot of attention with Redhat using it and I expect it to perform
pretty well.

However, saying all of that, btrFS is getting close and I have played some
with the new filesystem, I really like what I see and hope that I will be
using that sooner then later, especially for my raid needs.

:)
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