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NFS mount larger than 2TB

cdmackay

cdmackay

Active Member
Is anyone aware of any restrictions when mounting filesystems from a (Linux) NFS (v3) server?

A friend is trying this, and has found that his T2/CF crashes when attempting to play recordings within an NFSv3 export where the server filesystem is larger than 2TB. Is this expected?

i.e. if the server fs is < 2TB, all works fine. If the server fs is > 2TB, then although he can mount it, and cd around, and see it from the WebIF and on-telly IF, when he tries to play a recording the T2 resets itself.

In this case, he is mounting the NFS export via the Humax cmdline. He's found that it doesn't help if he exports, or mounts, a subset of the fs that is < 2TB, if the fs itself is > 2TB.

I'm not currently able to test this here, so I'm asking what is/isn't expected with T2 CF & NFSv3 mounts, and whether any particular revisions/kernels make any difference?

thanks!

edit: note that it's a Linux NFS server
 
Disks larger than 2TB are not supported unless they use GPT instead of MBR, and only then with the relevant patches to the kernel.

https://hummy.tv/forum/threads/large-external-hdds-over-2tb.7388/

https://hummy.tv/forum/threads/cfw-3-10-customised-firmware-v3-10-released.6992/

However, I note this is some kind of external file system accessed over a network. Even with GPT support in the kernel, there is no guarantee the Humax software has been compiled to be able to handle the number of bits required in the pointers to the data.
 
Last edited:
Thanks!

I don't think the partition table type (GPT) itself can be relevant, since the disk is not accessed directly by the Humax, merely via NFS.

The size is obviously relevant; but I thought the latest CF kernel supported larger disks, but I could well be wrong there? I need to check the release notes. thanks…
 
[The disk itself is, of course, GPT, since the Linux server wouldn't be able to deal with it otherwise]
 
cdmackay said:
The size is obviously relevant; but I thought the latest CF kernel supported larger disks, but I could well be wrong there? I need to check the release notes. thanks…
Click to expand...
Silly question but is your friend running a fairly recent version of the custom firmware?
 
Yes, I think that's it; thanks both of you: he is running CF, but I doubt it's recent enough.

From the release notes, it looks like 3.10 (13th March) is the release which added support for > 2TB. I'm sure he's not got that.

I'll follow up; thanks again.
 
And apols to BH: I had only read an earlier version of your post, via email, before replying; your edited post I should have checked before, since it contained the answers :)
 
cdmackay said:
Is anyone aware of any restrictions when mounting filesystems from a (Linux) NFS (v3) server?

A friend is trying this, and has found that his T2/CF crashes when attempting to play recordings within an NFSv3 export where the server filesystem is larger than 2TB. Is this expected?
[snip]
edit: note that it's a Linux NFS server
Click to expand...

Hi, any update from your friend?

I'm accessing NFS shares from a 3GB raid1 array (mdadm) on my Linux server via network-shares-automount and the USB option. The server's connected to the LAN via powerline ethernet adaptors which gives me a max speed of around 6MB/s, so not the fastest connection.

I was having lots of reboots of the T2 until I changed the NFS mount option of network-shares-automount from "soft" to "hard". I've seen it stated that "using soft mounts is not recommended as they can generate I/O errors in very congested networks or when using a very busy server". A "hard" mount, however, could freeze any related applications if the network becomes unreachable so I also added the "intr" option which "allows NFS requests to be interrupted if the server goes down or cannot be reached". Presumably this will solve any potential freezing problem but I don't actually know myself (until I've tested more thoroughly anyway).

Now all this could just be coincidental and anecdotal evidence but it's working for me so far. The following change I made was in '/mod/sbin/scanmounts'
Code: 
echo "mount -o hard,intr $host:/$folder /media/$name"
mount -o hard,intr "$host:/$folder" "/media/$name"

I'll report back after more testing.
 
Thanks very interesting.

my friend isn't using n-s-a; he just did the mount from the cmdline, without specifying hard/soft, and I am assuming the default is surely hard, but I will check.

No, we need to get his CF updated still, apols for delay…
 
yup, hard is indeed the default, but intr is not.

Mind you, that would normally only affect the ability to Ctrl-C a process that was stuck in an RPC/NFS call; not sure if provides for any automatic recovery.
 
cdmackay said:
yup, hard is indeed the default, but intr is not.

Mind you, that would normally only affect the ability to Ctrl-C a process that was stuck in an RPC/NFS call; not sure if provides for any automatic recovery.
Click to expand...

Ok, thanks for the clarification. I assumed "hard" was the default since I've never had to specify it using NFS before but at least it's clearly defined (by specifying it). I should also mention I access the T2 via NFS from my desktop (Linux) and have never had any problems there, using the mount options 'nolock,sync,vers=2'. I can't remember now why I'm using those options but it's all working well!

As for network-shares-automount, well I've not had a single reboot of the T2 since changing the mount options and have been watching various things from the server with no problem whatsoever.

Please post back if your friend finds out what's wrong his end.
 
My friend has updated one of his T2 to CF 3.12, and things still look awry:

Code: 
We're exporting from a Linux NFS server.

Everything looks fine from a Linux NFS client, but on the Humax:

Custom firmware version: 3.12 (build 3965)
Humax Version: 1.03.12 (kernel HDR_CFW_3.12)

humax3# mkdir /media/HP-archive-3

humax3# mount -r 194.119.178.61:/DATA/HUMAX/ARCHIVE-3 /media/HP-archive-3

humax3# df -m
Filesystem           1M-blocks      Used Available Use% Mounted on
194.119.178.61:/DATA/HUMAX/ARCHIVE-3
                       7554249   2714029   4764060  36% /media/HP-archive-3

yet no files are seen:

humax3# cd /media/HP-archive-3
humax3# ls
humax3# df -m .
Filesystem           1M-blocks      Used Available Use% Mounted on
194.119.178.61:/DATA/HUMAX/ARCHIVE-3
                       7554249   2714029   4764060  36% /media/HP-archive-3


Oddly, looking at it via the USB screen on the telly, he can see programmes, yet it still crashes on any attempt to play them.


I wonder: is /media a bad place to be mounting things, manually?
 
Is it a permissions issue? I initially had a problem where the T2 could not see any files in directories and anything top level that could be seen wouldn't play with an error of "Cannot support this file format". My Linux box, however, could access the files without problem.
 
chimeland said:
Is it a permissions issue? I initially had a problem where the T2 could not see any files in directories and anything top level that could be seen wouldn't play with an error of "Cannot support this file format". My Linux box, however, could access the files without problem.
Click to expand...

Thanks; yes, I told him about it before, but perhaps it's regressed; thanks for the reminder, will check.
 
cdmackay said:
Well, we could do, but at this stage it didn't seem necessary, just for testing. Mounting from cmdline and seeing the files shouldn't need any pkg support.
Click to expand...
That's as maybe, but we know it works so you shouldn't need to guess any parameters. It also actively recreates the mount when necessary.
 
Black Hole said:
That's as maybe, but we know it works so you shouldn't need to guess any parameters. It also actively recreates the mount when necessary.
Click to expand...

Well, chimeland suggests that its default parameters aren't right, anyway, although I think that could be coincidence. I don't see intr affecting anything there.

And we're not guessing any parameters, since they shouldn't be needn't; the defaults should work fine.

But yes, it's certainly a good thing to try, and we will!

thanks…
 
cdmackay said:
I don't see intr affecting anything there
Click to expand...

You're probably right but 'soft' definitely affected my setup! Since I changed that I've not had a single reboot or any issue whatsoever with the T2 (probably because of congestion on my LAN due to slow powerline adaptors).
 
chimeland said:
You're probably right but 'soft' definitely affected my setup! Since I changed that I've not had a single reboot or any issue whatsoever with the T2 (probably because of congestion on my LAN due to slow powerline adaptors).
Click to expand...

But hard is the default, so explicitly adding it to the mount options doesn't change anything. Or did you actually see it mounted as soft at any point? I agree, soft is generally to be avoided, for r/w.
 
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