Joe Landman wrote:

This I cannot tell you, as I don't have a comprehensive list of what uses what driver. I'd suggest looking at what drivers it loads for disks when it comes up. If dmraid comes up *and* enumerates devices, you have a strong probability that it is a fake-raid. This is not to say dmraid is bad. Again, its the underlying driver or chipset that we often run into problems with.

I should also point out that the presence of dmraid and device enumeration is still not sufficient for determining whether something is or is not a fake-raid. To wit

r...@crunch:~# df -h /data
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/2001b4d2306a71820-part1
                      4.6T  2.4T  2.2T  53% /data

and /data is on a most assuredly a hardware accelerated RAID. There were some additional tools I installed with the distribution which also installed device-mapper. I could turn it off, but then I have some other bits to work around. It's easier to leave it on.

FWIW: I am no fan of device mapper (the dm part of dmraid). It has caused us some serious grief in the past (serious grief == data lossage). Its not in a league with things like rieserfs, ext2, NTFS, and whatnot ...

When device mapper works correctly (as above) it works fine. A tautology/Yogi-Berra-ism for sure.

--
Joseph Landman, Ph.D
Founder and CEO
Scalable Informatics Inc.
email: land...@scalableinformatics.com
web  : http://scalableinformatics.com
       http://scalableinformatics.com/jackrabbit
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