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Software RAID 5 Kernel
http://forums.linhes.org/viewtopic.php?f=14&t=23994
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Author:  sfsouter [ Sat May 03, 2014 9:00 pm ]
Post subject:  Software RAID 5 Kernel

Hi, I'm trying to upgrade from a Mandriva 2008.1 installation to LinHES. My old installation uses RAID 5 with the distro installed on the RAID 5 array. I had to have a custom boot disk made for installation of Mandriva which had a kernel that could handle the software RAID 5. Is there anything that anyone knows to do to prepare a Kernal that can manage RAID 5? The install just shows my four disks individually instead of as a single RAID 5 array.

This 'fake raid' requires the dmraid module to be loaded as part of the kernel. Please let me know if anyone know how to do this install.

Thank you,
Scott

Author:  cahlfors [ Sun Jan 11, 2015 8:34 am ]
Post subject:  Re: Software RAID 5 Kernel

Hi there!
What you are describing is software raid. Fake raid is when hw manufacturers claim a board to be hardware raid, when the actual raid calculations are done in their software drivers.
It would make great sense to install the backend on raid. Personally, I would much prefer raid1, but the concept is the same.
Dunno if it's at all possible to set up the partitions manually and and have LinHES install on the dm devices instead of /dev/sdxy?

/Chris

Author:  jams [ Wed Jan 13, 2016 9:48 am ]
Post subject:  Re: Software RAID 5 Kernel

Software raid is considered unsupported with LinHES. All the tools are there but they are never tested.

Installation of LinHES using software raid is not possible with the standard install process. The installer only looks for /dev/sd* devices.

Now it is possible to create a custom config and skip the gui install, but it's rather tedious and I wouldn't recommend it.

Author:  cahlfors [ Wed Jan 13, 2016 3:05 pm ]
Post subject:  Re: Software RAID 5 Kernel

Thanks, jams!
Would it be possible to change the installer to look for /dev/md* devices as well?
I guess that is all it takes...

Thanks,
/Chris

Author:  graysky [ Wed Jan 13, 2016 3:15 pm ]
Post subject:  Re: Software RAID 5 Kernel

Would it be possible for you to add a smaller SSD or HDD to the system and install LH to that (for root and boot partitions etc.) and then add in your RAID5 which I assume you would use for media storage? Maybe we should back up: how is your RAID5 configured now?

Author:  mattbatt [ Wed Jan 13, 2016 9:50 pm ]
Post subject:  Re: Software RAID 5 Kernel

a year later and you haven't given up?
Why do you want a RAID 5? If your hardware is from 2008 then I would imagine that one modern HD would blow that RAID out of the water.
LinHES/MythTV uses storage groups that will distribute recordings across multiple individual hard drives but has no parity or redundancy. Recordings aren't that valuable to me. To each his own.

Author:  cahlfors [ Thu Jan 14, 2016 1:48 pm ]
Post subject:  Re: Software RAID 5 Kernel

Dunno if the OP has any interest in this thread any more, but my objective with a LinHES install on raid would be to have the base system on SSD. Given that I have three failed SSDs in front of me, which is 100% of my Linux installed SSDs failed within a year, I will require RAID1 to install the base system to SSD. A failed LinHES system would likely result in a divorce, so I want to protect it. :roll: I would much rather change an occasional failed RAID disk than going through a restore procedure with the associated downtime, time spent doing the work and tension of not knowing whether it will succeed or not. And my wife's missed recordings...

Regarding recordings, I have them on a separate, single disk currently, but would ultimately aim for putting them on a file server or NAS for the same reason.

Somehow, I am under the impression that I might not be the only one on this forum to consider my LinHES system "mission critical"... :oops:

Thanks,
/Chris

Author:  mattbatt [ Thu Jan 14, 2016 2:43 pm ]
Post subject:  Re: Software RAID 5 Kernel

Oh yes definitely mission critical and RAID 1 makes more sense.

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