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#1 2013-02-01 08:00:48

geohei
Member
Registered: 2013-01-08
Posts: 22

Fake-RAID1 data volume and Arch

Hi.

My motherboard (64bit, UEFI):
GA-Z77X-UD5H
Firmware: F14 (latest)

I use motherboard RAID1 (Fake-RAID1, Z77 chipset, not Marvell 88SE9172) to mirror two identical HDDs. The created volume is exclusively used as data volume (as opposed to system volume). The filesystem is NTFS. The volume works fine with Windows 7, which is already installed on the system HDD. Windows 7 detects the volume as a single HDD (the way it should be).

I plan to use Arch on the same box (multi boot, installation on system HDD where Windows 7 is already installed).

Question ... will Arch detect the volume also as one single HDD, and can I safely use (r/w) it without risk of data corruption?

Thanks,

Last edited by geohei (2013-02-01 13:17:50)

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#2 2013-02-05 10:20:50

gnux83
Member
Registered: 2012-06-02
Posts: 19

Re: Fake-RAID1 data volume and Arch

Hi,

In my opinion it will show up as a single device, because the controller will report it like this. Just to be sure, fire up a (LXK)Ubuntu live system and check smile

regards

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#3 2013-02-05 13:42:37

gondsman
Member
Registered: 2009-07-27
Posts: 84

Re: Fake-RAID1 data volume and Arch

If your controller is supported by dmraid or mdadm it will show up as a single device (under /dev/mapper/* or /dev/md126p*). Devices for each hd will still exist, but they will be ignored by udev and they will not be mounted, so you can safely use the device r/w.

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#4 2013-02-05 16:19:30

geohei
Member
Registered: 2013-01-08
Posts: 22

Re: Fake-RAID1 data volume and Arch

Many thanks for the replies.

In fact, dmraid seems to support Z77.

root@xxx:/dev/mapper# ls -l
total 0
crw------- 1 root root  10, 236 Feb  3 17:52 control
brw-rw---- 1 root disk 252,   1 Feb  3 17:52 isw_caaijgbdje_Data
lrwxrwxrwx 1 root root        7 Feb  3 17:52 isw_caaijgbdje_Data1 -> ../dm-0
lrwxrwxrwx 1 root root        7 Feb  3 17:52 isw_caaijgbdje_Data2 -> ../dm-2

The array appears as one removable drive (strange) but I did some test fills with subsequent md5 checks, and all this from both sides (Ubuntu and Windows 7) and it seems to work. However I read that there is a bug in dmraid with raid 1 in that apparently data corruption one drive can be replicated on the second. I couldn't find out which version of dmraid is affected or if the bug was fixed meanwhile.

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#5 2013-02-06 18:06:17

gondsman
Member
Registered: 2009-07-27
Posts: 84

Re: Fake-RAID1 data volume and Arch

I can't help with that particular bug, as I don't know anything about it. The only thing I can recommend is using mdadm over dmraid if your chipset is supported, as dmraid isn't actively developed anymore.

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