Selection advice for OpenEBS local pv's

MongoDB Percona Operator for MongoDB
1

Hi,

I was asked this week how easy it would be to expand a 2TB pvc in a 3 replica set mongodb cluster. We have used the OpenEBS local pv storageclass, and I’ve edited our custom storageclass to add allowVolumeExpansion: true in our test setup, and then altered one of the existing pvc’s to increase it’s size,

It would appear however that volume expansion is not included in that storageclass, judging by the error recorded and the lack of expansion messages (I’m using the article about expansion without downtime)

So two questions. First, do you have a preferred OpenEBS local pv storageclass that allows expansion (LVM local PV perhaps, which I’ll be testing later)

Second - is there a way of expanding a local pvc, or is it a replacement only option. The drives in question are 14 TB hdd, so we don’t need NVMe support or anything fancy

Any advice much appreciated.

Thanks,

Mike

2

Hello @Michael_Shield ,

good question!

If you use smth like local pv with hostpath - you can’t expand it. The only option is to replace. With replica set with 3 nodes you can do it without downtime. At the same time, remember that hostpath itself is just a mount point. So its size is not really limited by anything except the HDD capacity of your machine.

As you rightfully mentioned, LVM local PV supports expansion: https://github.com/openebs/lvm-localpv/blob/develop/docs/resize.md

It is hard to recommend anything not knowing your setup. But I can say that we see a lot of production use of cStor: cStor Overview | OpenEBS Docs

3

Thanks Sergey,

We used openebs local PV as most of the drives in this cluster are NVMe, and it performs v well. Sizing of our Mongo drives was always a little hazy, but I think LVM Local PV will probably do the trick here.

Cheers,

Mike