RAID question

[soakes]

Quick question as the documentation doesn't seem to shed any light on this. I am a little worried that it says raid0. The data is replicated to two nodes when the shared volume was created so surely this should say RAID1?

I just want to make sure that my data is safe. Is there any way to change this to RAID1?

Status: PX is operational
License: PX-Developer
Node ID: 48f1b703-6d6e-4cea-b7f0-0a4eb7294b95
    IP: 172.30.1.220
    Local Storage Pool: 1 pool
    POOL    IO_PRIORITY RAID_LEVEL  USABLE  USED    STATUS  ZONE    REGION
    0   HIGH        raid0       20 GiB  276 MiB Online  default default
    Local Storage Devices: 1 device
    Device  Path        Media Type      Size        Last-Scan
    0:1 /dev/xvdb   STORAGE_MEDIUM_SSD  20 GiB      06 Dec 17 18:02 UTC
    total           -           20 GiB
Cluster Summary
    Cluster ID: ef4d3327-ad43-42f8-a419-f5b76fd95423
    Cluster UUID: a68955bc-d6e9-480b-9f9f-92a7f2faf44d
    Nodes: 3 node(s) with storage (3 online)
    IP      ID                  StorageNode Used    Capacity    Status
    172.30.3.220    a9fdadb3-558c-425f-995a-08e14b6d855c    Yes     1.2 GiB 100 GiB     Online
    172.30.2.220    a73ec252-3ec3-452e-b7f1-649943381e81    Yes     1.3 GiB 100 GiB     Online
    172.30.1.220    48f1b703-6d6e-4cea-b7f0-0a4eb7294b95    Yes     0 B 20 GiB      Online   (This node)

[prabirpaul]

The raid level controls how the data is laid out locally on this node. This is a per node option and is set during node initialization through the config.json.

The HA (or replication) level controls how data is laid out globally within the cluster. This is a per volume option. This is set during volume create and can be changed later.

Are you looking to change the device raid level or the HA level of the volume?

[soakes]

Hi @prabirpaul thank you for explaining that.

I am trying to build a shared docker storage solution using two storage nodes plus one storage-less node for the quorum. However, it seems that when I drop one of the storage nodes, the whole cluster fails with:

Status: PX is not in quorum
License: PX-Developer
Node ID: d148adb6-fa00-47ff-bcab-0d15eb7e0c7c
    IP: 172.30.1.220
    Local Storage Pool: 0 pool
    POOL    IO_PRIORITY RAID_LEVEL  USABLE  USED    STATUS  ZONE    REGION
    No storage pool
    Local Storage Devices: 0 device
    Device  Path    Media Type  Size        Last-Scan
    No storage device
    total       -   0 B
Cluster Summary
    Cluster ID: ef4d3327-ad43-42f8-a419-f5b76fd95423
    Cluster UUID: 886939b9-6904-492f-936f-ca5cf53aa959
    Nodes: 2 node(s) with storage, 1 node(s) without storage
    IP      ID                  StorageNode Used        Capacity    Status
    172.30.3.220    94332c3b-b8cb-4c35-849f-bf996136c764    Yes     Unavailable Unavailable Not Available
    172.30.2.220    49582994-4d64-4586-a614-577dcdce5f4d    Yes     Unavailable Unavailable Not Available
    172.30.1.220    d148adb6-fa00-47ff-bcab-0d15eb7e0c7c    No      Unavailable Unavailable Not in Quorum (This node)
Global Storage Pool
    Total Used      :  0 B
    Total Capacity  :  0 B

I would of expected that quorum should of still been possible due to the storage-less node but alaias it isn't and so all nodes then goes offline.

Is there something I am miss understanding?

So in short I just want to have one extra copy of the data in case a node fails but the node still needs to be able to function while new disks etc could be installed.

I have tried several configurations but all seems to break when one of the two storage nodes are offline.

[prabirpaul]

Because the storage-less nodes do not participate in quorum decisions, if you take down a storage node the cluster is out of quorum. You should be able to take own the storage-less node though. You would need a cluster size of 3 nodes to be able to do what you mentioned above.

Create volumes with HA level==2, which could create 1 extra copy for each volume distributed equally among all 3 nodes.

[soakes]

Thank you kindly. This does explain everything.

[soakes]

@prabirpaul One last quick question if I may, the 1TB limit, as I want to mirror the data for HA reasons, would that mean I am limited to about 333GB? or can I still have 1TB on each node and just leave it set to HA level==2? and the whole 1TB would be usable?

[prabirpaul]

Sure. The size of the replicas does not count towards the volume size limit. You should be able to create volumes of 1T with HA factor of 1, 2 or 3.

[soakes]

Thank you @prabirpaul, this is great news.