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Change Summary v1.8

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Kiran Mova edited this page Apr 14, 2020 · 9 revisions

Status: Released on 15-Mar-2020

Table of contents

Security Vulnerabilities Fixed

None

Breaking Changes

OpenEBS v1.8 includes a critical fix (#2956) for Jiva volumes that are running in version 1.6 and 1.7. You must use these pre-upgrade steps to check if your jiva volumes are impacted. If they are, please reach out to us on [OpenEBS Slack] (https://openebs-community.slack.com/messages/openebs-users/)  or Kubernetes Slack #openebs channel for helping you with the upgrade.

This release deprecates OpenEBS 0.7.x version. The steps to upgrade are here.

New Capabilities

  • [cStor] Added support for configuring capacity threshold limit for a cStor Pool. The default threshold limit is set at 85%. The threshold setting has been introduced to avoid a scenario where pool capacity is fully utilized, resulting in failure of all kinds of operations - including pool expansion. With this release, the cStor Pool will be marked as read-only when the read-only threshold value is crossed. (https://github.com/openebs/libcstor/pull/43 https://github.com/openebs/cstor/pull/289 https://github.com/openebs/maya/pull/1623 https://github.com/openebs/maya/pull/1609 https://github.com/openebs/maya/pull/1624)

    The threshold can be specifed in the SPC during the initialization as follows:

    spec:
  name: cstor-pool
  type: sparse
  maxPools: 3
  poolSpec:
    poolType: striped
    roThresholdLimit: 80

    For existing pools, the threshold value can be changed by modifying the value on the CSP.

    When the threshold limit is crossed and the pool is turned, the CSP will contain the following event.

    Events:
  Type     Reason                 Age                  From       Message
  ----     ------                 ----                 ----       -------
  Normal   Synced                 12m                  CStorPool  Received Resource create event
  Normal   Synced                 12m (x2 over 12m)    CStorPool  Received Resource modify event
  Normal   Created                12m                  CStorPool  Resource created successfully
  Normal   Synced                 8m23s                CStorPool  Received Resource create event
  Normal   Imported               8m22s                CStorPool  Resource imported successfully
  Normal   Synced                 29s (x4 over 8m23s)  CStorPool  Received Resource modify event
  Warning  PoolReadOnlyThreshold  21s                  CStorPool  Pool storage limit reached to threshold. Pool expansion is required to make it's replica RW

Alpha Feature Updates

Enhancements

None

Major Bug Fixes

E2E Testing Updates

E2E Platform Updates

Automated end-to-end tests are executed using the GitLab runner. The following platforms were verified.

Backward Incompatibilities

This release removes the support for managing volumes that are in OpenEBS 0.8.x version or earlier. Please upgrade your volumes in versions 0.8.2 or earlier to 1.0, before upgrading to this release

For releases prior to 1.0, please refer to the respective release notes and upgrade steps.

  • From 1.0.0: None.

  • From 1.2: If the status of CSP is either in Init or PoolCreationFailed, then cstor-pool-mgmt container in pool pod will attempt to create the pool. So, when there is a need to re-create pool for the same CSP due to ephemeral storage, CSP CR related to this pool needs to be edited to set status.phase as Init. As part of reconciliation, cstor-pool-mgmt container of pool pod will attempt to recreate the pool. Refer https://github.com/openebs/maya/pull/1401 for more details.

  • From 1.3.0: None

  • From 1.4.0: None

  • From 1.5.0: Dumping cores has been disabled by default for cStor pool and NDM daemonset pods. This can be enabled by setting an ENV variable ENABLE_COREDUMP to 1. The ENV setting can be added in cStor pool deployment for dumping core for cStor pool pod and the ENV setting can be added in ndm daemonset spec for dumping core for ndm daemonset pods.

  • From 1.6.0, 1.7.0: OpenEBS v1.8 includes a critical fix (#2956) for Jiva volumes that are running in version 1.6 and 1.7. You must use these pre-upgrade steps to check if your jiva volumes are impacted. If they are, please reach out to us on [OpenEBS Slack] (https://openebs-community.slack.com/messages/openebs-users/)  or Kubernetes Slack #openebs channel for helping you with the upgrade.

Note: As part of OpenEBS upgrade or installation, maya-apiserver pod will restart if NDM blockdevice CRDs are not created before the creation of maya-apiserver. https://github.com/openebs/maya/pull/1381

Install

Prerequisite to install

  • Kubernetes 1.13+ is installed. If using Kubernetes 1.16+ then please use OpenEBS 1.4 and above.
  • Make sure that you run the below installation steps with cluster admin context. The installation will involve creating a new Service Account and assigning to OpenEBS components.
  • Make sure that iSCSI Initiator is installed on all the Kubernetes nodes.
  • Node-Disk-Manager (NDM) helps in discovering the devices attached to Kubernetes nodes, which can be used to create storage pools. If you like to exclude some of the disks from getting discovered, update the filters in NDM Config Map to exclude paths before installing OpenEBS.
  • NDM runs as a privileged pod since it needs to access the device information. Please make the necessary changes to grant access to run in privileged mode. For example, when running in RHEL/CentOS, you may need to set the security context appropriately. Refer Configuring OpenEBS with selinux=on

Install using kubectl

kubectl apply -f https://openebs.github.io/charts/openebs-operator-1.8.0.yaml

Install using helm stable charts

helm repo update
helm install --namespace openebs --name openebs stable/openebs --version 1.8.0

For more details refer to the documentation at https://docs.openebs.io/

Upgrade

The steps to upgrade are here. Kubernetes Job-based upgrades to version 1.8 is supported only from 1.0 or higher and follow a similar process like earlier releases.

  • Upgrade OpenEBS Control Plane components.
  • Upgrade Jiva PVs to 1.8, one at a time
  • Upgrade CStor Pools to 1.8 and its associated Volumes, one at a time.

For upgrading from releases prior to 1.0, please refer to the respective release upgrade here.

Uninstall

The recommended steps to uninstall are:

  • delete all the OpenEBS PVCs that were created
  • delete all the SPCs (in case of cStor)
  • ensure that no volume or pool pods are pending in terminating state kubectl get pods -n <openebs namespace>
  • ensure that no openebs cStor volume custom resources are present kubectl get cvr -n <openebs namespace>
  • delete all openebs related StorageClasses.
  • delete the openebs either via helm purge or kubectl delete

Uninstalling OpenEBS doesn't automatically delete the CRDs that were created. If you would like to remove CRDs and the associated objects completely, run the following commands:

kubectl delete crd castemplates.openebs.io
kubectl delete crd cstorpools.openebs.io
kubectl delete crd cstorvolumereplicas.openebs.io
kubectl delete crd cstorvolumes.openebs.io
kubectl delete crd runtasks.openebs.io
kubectl delete crd upgradetasks.openebs.io
kubectl delete crd storagepoolclaims.openebs.io
kubectl delete crd storagepools.openebs.io
kubectl delete crd volumesnapshotdatas.volumesnapshot.external-storage.k8s.io
kubectl delete crd volumesnapshots.volumesnapshot.external-storage.k8s.io
kubectl delete crd disks.openebs.io
kubectl delete crd blockdevices.openebs.io
kubectl delete crd blockdeviceclaims.openebs.io
kubectl delete crd cstorbackups.openebs.io
kubectl delete crd cstorrestores.openebs.io
kubectl delete crd cstorcompletedbackups.openebs.io
kubectl delete crd cstorvolumeclaims.openebs.io
kubectl delete crd cstorpoolclusters.openebs.io
kubectl delete crd cstorpoolinstances.openebs.io

Note: As part of deleting the Jiva Volumes - OpenEBS launches scrub jobs for clearing data from the nodes. The completed jobs need to be cleared using the following command:

kubectl delete jobs -l openebs.io/cas-type=jiva -n <namespace>

Limitations / Known Issues

For a more comprehensive list of open issues uncovered through e2e and community testing, please refer to GitHub open issues. Here is a quick summary of common known issues.

  • The current version of OpenEBS cStor is not optimized for performance-sensitive applications.

  • Upgrade of alpha features like cStor Pools using new schema (CSPC), cStor CSI Driver, Jiva CSI Driver, MayaStor and ZFS Local PV are not supported.

  • A healthy volume(cStor or Jiva) which has a slow replica due to disk slowness or has huge network latency can cause volume read-only. In this case, a write IO to that slow replica takes more than 15-30 seconds to communicate with its controller which might cause disconnection from the initiator.

  • Over provisioning is enabled by default on cStor volumes. In case of application such as ElasticSearch, Postgresql which uses ext4 filesystem without unmap support and when a data is written and modified, ext4 tends to use new blocks of storage without sending any delete (unmap) requests back to the underlying block storage - like cStor. This can be avoided by setting a configuration on storage class based on resource quota to set a limit on the sum of capacity allocated to all the PVCs to be within the available capacity of the underlying cStor Pools. Further details are tracked here.

  • cStor volume will be offline when ReplicationFactor is not greater than 50% and then cStor volume will not come online automatically and then reconstructing data to recovered replicas. It requires manual steps to make the volume online and reconstruct the data to the replaced replicas from a healthy replica once the cStor volume is online.

  • If a pending PVC related to openebs-device StorageClass is deleted, there are chances of getting stale BDCs which ends up in consuming BDs. You have to manually delete the BDC to reclaim it.

  • In OpenShift 3.10 or above, NDM daemon set pods and NDM operators will not be upgraded if NDM daemon set's DESIRED count is not equal to the CURRENT count. This may happen if nodeSelectors have been used to deploy OpenEBS related pods OR if master/other nodes have been tainted in the k8s cluster.

  • Jiva Controller and Replica pods are stuck in Terminating state when any instability with the node or network happens and the only way to remove those containers is by using docker rm -f on the node. https://github.com/openebs/openebs/issues/2675

  • cStor Target or Pool pods can at times be stuck in a Terminating state. They will need to be manually cleaned up using kubectl delete with 0 sec grace period. Example: kubectl delete deploy -n openebs --force --grace-period=0

  • cStor pool pods can consume more memory when there is continuous load. This can cross the memory limit and cause pod evictions. It is recommended that you create cStor pools by setting the Memory limits and requests.

  • Jiva Volumes are not recommended if your use case requires snapshots and clone capabilities.

  • Jiva Replicas use a sparse file to store the data. When the application causes too many fragments (extents) to be created on the sparse file, the replica restart can cause replica to take longer time to get attached to the target. This issue was seen when there were 31K fragments created.

  • Volume Snapshots are dependent on the functionality provided by Kubernetes. The support is currently alpha. The only operations supported are:

    • Create Snapshot, Delete Snapshot and Clone from a Snapshot. Creation of the Snapshot uses a reconciliation loop, which would mean that a Create Snapshot operation will be retried on failure until the Snapshot has been successfully created. This may not be a desirable option in cases where Point in Time snapshots are expected.

  • If you are using K8s version earlier than 1.12, in certain cases, it will be observed that when the node hosting the target pod is offline, the target pod can take more than 120 seconds to get rescheduled. This is because target pods are configured with Tolerations based on the Node Condition, and TaintNodesByCondition is available only from K8s 1.12. If running an earlier version, you may have to enable the alpha gate for TaintNodesByCondition. If there is an active load on the volume when the target pod goes offline, the volume will be marked as read-only.

  • If you are using K8s version 1.13 or later, that includes the checks on ephemeral storage limits on the Pods, there is a chance that OpenEBS cStor and Jiva pods can get evicted - because there are no ephemeral requests specified. To avoid this issue, you can specify the ephemeral storage requests in the storage class or storage pool claim. (https://github.com/openebs/openebs/issues/2294)

  • When the disks used by a cStor Pool are detached and reattached, the cStor Pool may miss detecting this event in certain scenarios. Manual intervention may be required to bring the cStor Pool online. (https://github.com/openebs/openebs/issues/2363)

  • When the underlying disks used by cStor or Jiva volumes are under disk pressure due to heavy IO load, and if the Replicas take longer than 60 seconds to process the IO, the Volumes will get into Read-Only state. In 0.8.1, logs have been added to the cStor and Jiva replicas to indicate if IO has longer latency. (https://github.com/openebs/openebs/issues/2337)

  • LocalPV RawBlock volumes are not supported when the application container is running in privileged mode.

  • Upgrade of alpha features like cStor Pools using new schema (CSPC), cStor CSI Driver, MayaStor and ZFS Local PV are not supported.

  • An application may go into read-only state during the Jiva upgrade if multipath support is enabled on the Nodes. It requires manual relogin of iscsi on the node where the application pod is running or scheduling of the application onto another node to make the application into running state.

Support

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