On 6 Dec 2016 5:14 am, "Nicholas Geovanis" <nickgeovanis@gmail.com> wrote:
>
> I'd like to make sure I'm taking away the right thing from this conversation.
> It seems we have high-level recommendations _not_ to use LVM RAID1.
> Not just over MD, simply don't use it at all. Do I get that right?
>
> On Mon, Dec 5, 2016 at 4:25 AM, Jonathan Dowland <jmtd@debian.org> wrote:
>>
>> On Sat, Dec 03, 2016 at 07:39:37PM +0100, Kamil Jońca wrote:
>> > So far I used lvm with raid1 device as PV.
>> >
>> > Recently I have to extend my VG
>> > (https://lists.debian.org/debian-user/2016/11/msg00909.html)
>> >
>> > and I read some about lvm.
>> > If I understand correctly, LVM have builtin RAID1 functionality.
>> > And I wonder about migrating
>> > lvm over md --> (lvm with raid1) over physical hard drive partitions.
>> >
>> >
>> > Any cons?
>>
>> MD is older, has had more development and is generally considered to be
>> more robust. I would always choose to do RAID with MD, directly on the
>> disks, and put LVM on top of the MD virtual block devices.
>>
>> --
>> Jonathan Dowland
>> Please do not CC me, I am subscribed to the list.
>
>
It depends. If you are using cloud services with remote shared storage like AWS EBS it does not make sense using LVM on top of RAID. To me it is just adding complexity to already complex SAN storage. You also have no idea what the block devices presented to the VM are coming from it might be a file coming over iSCSI. I've been using LVM raid on AWS EBS for years without any issues. My advice is test and match them all before you make your decision each ones user case and experience is different.