[linux-lvm] LVM mirroring or mdadm

[Diego Jacobi]

Hi.


For te mirrorlog you can partition your new disk with 2 lvm
partitions. One for logs.
A mirror log are normally 4 Mb for each mirror, at least in my current system.
I maked a 1Gb partition only for logs and it is way too much, but 1 Gb
in current disks is nothing.
You could make a 200 Mb partition and it will still being way too much.
And the rest of the disk for boot, swap and lvm.

Having mirroring in LVM is great, you will only use 1 tool for
everything and it is much more flexible, however, i dont know yet how
to do parallel readings in linux, and i cant find any information
about it.
Si if you want raid for improving read speed, i cant help you yet, but
if you want it to duplicate your data, then i would recommend lvm for
flexibility.

Cheers.
Diego



2009/7/13 Koen Vermeer <koen at vermeer.tv>:
> On Mon, 2009-07-13 at 17:32 +0100, Imobach González Sosa wrote:
>> I've got a pair of identical Seagate disks on a server and I'm considering
>> using a software RAID (RAID1). I was thinking of setting up LVM on a mdadm
>> RAID, but I've read that LVM has support itself for mirroring.
>> So, what is the better approach? Using LVM mirroring capabilities or putting
>> the LVM on a mdadm RAID 1?
>
> I faced the same dilemma and chose RAID instead of LVM mirroring. The
> reason is that LVM requires an extra log partition when doing mirroring.
> (In fact, this is not strictly true, but otherwise it will rebuild the
> mirror after each reboot.) The log partition doesn't have to be big, but
> I didn't like the additional tinkering.
>
> If there exists some easy way around the extra partition, I'd probably
> switch to an LVM-only solution. But for now, it's LVM-over-RAID for me.
>
> Koen
>
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