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Following a discussion with a potential client about building a ‘truly redundant system’, thought about warning solution developer of this thread on LKML :
There are talks of deprecating md-multipath (from the Linux kernel, for those that weren’t really following). Quite a few systems would be moving from md-devices to “something else”.
The new flavor of the month (or year, following your P.O.V.) is dm-multipath. The configuration file is straight forward and the RedHat Documentation is very decent.
Ok, I know: the names are confusing. MD device drivers stand for “multiple devices” and is also know as Linux software raid solution. DM is the acronym of “Device Mappers” and is more known as the pre-requisite for LVM2 (not LVM1, but then who still use that!?) or as the foundation of dm-crypt, a free software interface allowing block level encryption through Linux (v2.6+) kernel cryptoapi framework.
On the topic of names; This is where I insert this familiar rant. I’ve never quite understood the MD as ‘multiple device’ name. Linux kernel device names, other than the ones directly linked to hardware, are normally named after their function not a ’source’. In this instance, MD as ‘meta-device’ would make perfect sense – A device about devices. Anyway… it wasn’t named like that…
Anyway, no labs planned for any of those two techs (yet) or for the migration of md toward dm. We never know, I’ll keep you guys informed.
tagged with : , consultant, freesoftware, GNU/Linux, SAN, Technique | permalink