Re: Advice on raid/lvm

randall wrote:
Tapani Tarvainen wrote:
On Thu, Apr 09, 2009 at 08:50:34PM -0500, Mark Allums (mark@xxxxxxxxxx) wrote:

Douglas A. Tutty wrote:
Is there an advantage of software raid10 over multiple raid1 arrays
joined with LVM? Capacity can be dynamically added with pairs of disks.

Only one: simplicity. It would make it easier for someone to understand, in the beginning.

Curiously, I would've thought the opposite, that is, bunch of separate
raid1 arrays would be easier to understand than raid10.
Raid1 is conceptually simple compared to any other raid level,
and if you're using lvm anyway, it doesn't make much difference
whether physical volumes are disks or disk pairs.

Anybody want to claim being a newbie and having an opinion here?

ehhmm,,

not a complete newbie anymore but the memory is still fresh ;)

one might argue that at least with etch raid1 + LVM would be easier since raid10 was not covered by the installer.
also you might generally say that people often become familiar with raid1 first since it is the most simple affordable solution at first for the most simple scenario's
raid1 vs raid 10 i think i would say that raid1 is easier to understand since it is 50% less complex.

but then again, 3 points above for raid1 being easier, assuming one already knows and understands LVM, if not it becomes a different story.

i still remember that when being fresh on checking the difference between raid levels on the wiki doing things like this
http://www.songshu.org/index.php/setup-raid-10
seemed complex to me at first, but so did LVM with its groups and volumes, so i think it depends on your previous experience and comfort level what really is easier.


I of course meant raid 10 is simpler than 92 LVM volumes groups, under any physical scheme.

raid 1 is simplest, other than a single basic disk, but I seem to remember the option being RAID 5 or something else, and I was trying to say that I like RAID 10 better than I like RAID 5.

I also think that RAID 10 is pretty simple to understand. Take four disks. Make two pairs. Mirror each pair (RAID 1), then stripe across the pairs (RAID 0). It's just a combination.

And then, you can do any logical thing you want on top of that.

Mark Allums







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