MInimum volume size in ceph-csi

[Madhu-1]

What is the minimum volume size supported in ceph-csi for both cephfs and rbd?
I fell an input validation is missing for the same.
@rootfs @gman0 ^^

[gman0]

For cephfs (configuration docs):

Notes on volume size: when provisioning a new volume, max_bytes quota attribute for this volume will be set to the requested volume size (see Ceph quota documentation). A request for a zero-sized volume means no quota attribute will be set.

smallest quota unit is in bytes.

For RBD, smallest allocation unit seems to be in megabytes http://docs.ceph.com/docs/mimic/rbd/rados-rbd-cmds/#creating-a-block-device-image - even though the RBD plugin passes the size in gigabytes, hmm... @rootfs ?

[lelvisl]

1Gi is minim - #213

[Madhu-1]

@lelvisl we need to figure out what is the minimum value for both cephfs and RBD

I think once we address this issue #213 will be fixed

[lelvisl]

ok, really looking forward to the decision.

[Madhu-1]

@rootfs need your input on this.

[rootfs]

let's follow in-tree rbd convention here https://github.com/kubernetes/kubernetes/blob/master/pkg/volume/rbd/rbd_util.go#L584

[Madhu-1]

@rootfs what about cephfs? same applies for that one also?

[rootfs]

@Madhu-1 good idea

[gman0]

Just a general knowledge question, could you please explain where ceph enforces limit for directory quota to be >1MiB for cephfs? As far as I know, quota is measured in bytes, so it can be as little as 1B no?

[Madhu-1]

@gman0 if we enforce the rule, we will face this issue in external-provisioner kubernetes-csi/external-provisioner#199

[gman0]

@Madhu-1 ok but that's an issue with that particular sidecar container. AFAIK neither cephfs nor CSI has such requirement where the quota has to be >1MiB.

[Madhu-1]

that's an issue with that particular sidecar container. AFAIK neither cephfs nor CSI has such a requirement where the quota has to be >1MiB.

yes, you are right, what could be the minimum volume size we can create in cephfs?

let's follow in-tree rbd convention here https://github.com/kubernetes/kubernetes/blob/master/pkg/volume/rbd/rbd_util.go#L584

@rootfs we cant use this utility function in cephfs as in current code we can create volume of size in bytes (if we want to use the function minimum volume size will be of 1Mib)

[Madhu-1]

@poornimag can you consider this scenario for cephfs volume create?

[humblec]

@Madhu-1 iic, we have a roundoff now for both rbd and cephfs volumes whlie provisioning. With that I think this issue can be closed.

[Madhu-1]

closing this one as we have default for rbd and for cephfs 0 is valid