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Is dmraid45 still needed for Intel RST-based Raid5?
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Zarhan
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PostPosted: Sat Oct 13, 2012 10:34 am    Post subject: Is dmraid45 still needed for Intel RST-based Raid5? Reply with quote

I'm still running kernel 2.6.39 in my desktop, which dual-boots to Windows. It's using Intel Fakeraid. I've heard that the built-in raid (that doesn't need the patches listed at http://en.gentoo-wiki.com/wiki/RAID/dm-raid45 ) support in kernel can in more recent versions detect the raid volumes in Intel's format without the needing any patches.

Is this true?

If yes, what steps do I need to do when upgrading my kernel? What userspace programs do I need? Do I need to switch from dmraid to mdadm or something like that? I've been using genkernel for the actual kernel building since initrd is needed for initializing the raid volumes.

(If not true, pointers to dmraid45 patch for recent kernels much appreciated)
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NeddySeagoon
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PostPosted: Sat Oct 13, 2012 3:56 pm    Post subject: Reply with quote

Zarhan,

Yes its true - you need mdadm in userspace I'm not sure what you need in the kernel.

Install mdadm and read its man page - that may help.
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Zarhan
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PostPosted: Thu Nov 22, 2012 5:30 am    Post subject: Reply with quote

I've been trying to look into this, but haven't been able to find any simple guide on how to migrate from dmraid-based Intel RST to mdadm-based one. Anyone got a pointer? The metadata on the disk shouldn't change, just the kernel module and userspace tools used to access it.
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NeddySeagoon
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PostPosted: Thu Nov 22, 2012 6:50 pm    Post subject: Reply with quote

Zarhan,

Read the mdadm man page - particularly the bit about containers.

I'm not sure about the metadata in disk not changing.
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NeddySeagoon

Computer users fall into two groups:-
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Zarhan
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PostPosted: Fri Jan 25, 2013 12:52 pm    Post subject: Reply with quote

Turns out that all I had to do was compile a new kernel, install mdadm, and do a genkernel recompilation. Easier than I thought. Initramfs as built by genkernel automounted the whole shebang.

I didn't even run into the problem that some folks had about raid volumes being marked dirty (https://bugs.gentoo.org/show_bug.cgi?id=395203 )
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Zarhan
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PostPosted: Sat Jan 26, 2013 9:14 am    Post subject: Reply with quote

Meh, apparently dirty arrays did occur anyway. Thankfully, I got things working with my own script (pasted to http://forums.gentoo.org/viewtopic-p-7231546.html#7231546 )
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