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Adding Secondary Storage
http://forum.linhes.org/viewtopic.php?f=22&t=22588		 Page 1 of 1
Author:  jlp_engineer [ Tue Apr 10, 2012 11:33 pm ]
Post subject:  Adding Secondary Storage
With LinHES, I have noticed that the backend folders are very gracefully shared to the frontends, which is a really nice touch. My question:

Is there an easy way to add a second hard disk on the backend, and keep the same directory structure?

I tried mounting a second disk I had, already partitioned and formatted with XFS, at /myth/video (I wanted to add storage for my DVD ISO collection), but I could not see any files stored on the disk at the mount point, and I could not see any of the ISO's on the Frontend (shared through NFS). Are you not allowed to use a mount point in an NFS exported share?

I will be using a NAS connected via NFS for backups, and a directly attached RAID box for all the storage on my backend. I am just a little too much of a novice to know exactly how to make it all work together. :oops:

Hints anyone?

TIA
Author:  christ [ Wed Apr 11, 2012 8:33 pm ]
Post subject:  Re: Adding Secondary Storage
Mythtv is generally moving exclusively to Storage Groups (SG) so you will not need NFS. 0.24 is kind of at that pivot point of moving to SGs. In 0.24 you can use both. I suspect by 0.26 or so myth won't support NFS quite as well.

With SGs you can add additional drives as additional storage in the storage group and myth will load balance between the disks.

I'm contemplating moving to SGs soon. I have only held off because I liked the warm and fuzzy feeling of being able to switch to mplayer for some of the more challenging files.

If you stick with NFS then on the backend you could mount the drive to your myth directory structure. In the mythtv service menus (or perhaps setup), IIRC, you can add multiple paths somewhere. I couldn't find it when I just looked so it may have been removed.
Author:  jlp_engineer [ Thu Apr 19, 2012 12:04 am ]
Post subject:  Re: Adding Secondary Storage
Anyone have any thoughts on this?

I am thinking about trying to see if I can mount an additional hard disk within the folder structure of the /myth folder that is created on the BE, but when I do this (mount /dev/sdb /myth/video), but the files on the added drive do not appear in the folder structure /myth/video, so I am doing something wrong or the permissions are screwed up. I see that the myth folder has 65634 in the group and user permissions, and I have not seen this before. When I try to change it, it refuses the command.

Help is needed.
Author:  turpie [ Thu Apr 19, 2012 1:01 am ]
Post subject:  Re: Adding Secondary Storage
Can I just clarify something?
Are you trying to merge the existing contents of /myth/video with the contents of /dev/sdb?
If so I dont think you can do that without some type of union fs.

Also can you just mount a drive like that (/dev/sdb), on my setup I have to mount a partition such as /dev/sdb1.
Author:  jlp_engineer [ Thu Apr 19, 2012 4:22 pm ]
Post subject:  Re: Adding Secondary Storage
turpie wrote:
Can I just clarify something?
Are you trying to merge the existing contents of /myth/video with the contents of /dev/sdb?
If so I dont think you can do that without some type of union fs.

Also can you just mount a drive like that (/dev/sdb), on my setup I have to mount a partition such as /dev/sdb1.


First, let me thank you for your reply. I appreciate it!!!

No, I am not trying merge them, but rather use /myth/video as a mount point for the disk I am adding. There are a few directories and files on the disk I am adding and the disk is formatted XFS. Also, I made a mistake when I typed in the disk identifier. You are right, it is and should be sdb1. However, when I mount it, and then do a "ls /myth/video", I see no files or folders, and the folders that were there are gone. I realize I am doing something wrong.... Do I have to make sure the mount point is an empty folder? Does it matter?

I just need to learn the "in's and out's" and then I can deal with this stuff on my own, but finding documentation that covers very specific issues like this is difficult to find. The standard documentation just covers the standard scenarios, and it is always different enough to make me doubt what I am doing.

Thanks for your help.
Author:  turpie [ Thu Apr 19, 2012 10:25 pm ]
Post subject:  Re: Adding Secondary Storage
I did something quite similar for a while on my system. I outgrew my first drive so I moved the contents of /myth/video of my existing drive to another drive that I mounted at /myth/video. Though I think I actually moved or renamed the existing directory to "videoold" and then created a new "video" directory for mounting to.

According to "man mount"
Quote:
The previous contents (if any) and owner and mode of dir become invisible, and as long as this filesystem remains mounted, the pathname dir refers to the root of the filesystem on device.

So it shouldn't matter that the previous directory had any contents.

What do you get when you enter the "mount" command without any parameters?
Author:  tjc [ Sat Apr 21, 2012 12:11 pm ]
Post subject:  Re: Adding Secondary Storage
If you mount another filesystem over an existing directory then the original contents of the directory are not accesible. This is normal and the way mount has worked "forever".
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