I use db as pod with file storage.
the issue is when I stop and start the DB pod, data is lost
and I have to recreate tables
How to resolve it please
PVC will do the JOB for you. But which storage class are you using ?
And Reclaim Policy of volume plugin.
For your reference:
in PV.yaml
persistentVolumeReclaimPolicy: Recycle
From K8s Docs:
Reclaim Policy
Current reclaim policies are:
Retain -- manual reclamation
Recycle -- basic scrub (rm -rf /thevolume/*)
Delete -- associated storage asset such as AWS EBS, GCE PD, Azure Disk, or OpenStack Cinder volume is deleted
Currently, only NFS and HostPath support recycling. AWS EBS, GCE PD, Azure Disk, and Cinder volumes support deletion.
From Kubernetes Docs:
For volume plugins that support the Delete reclaim policy, deletion removes both the PersistentVolume object from Kubernetes, as well as the associated storage asset in the external infrastructure, such as an AWS EBS, GCE PD, Azure Disk, or Cinder volume. Volumes that were dynamically provisioned inherit the reclaim policy of their StorageClass, which defaults to Delete. The administrator should configure the StorageClass according to users' expectations; otherwise, the PV must be edited or patched after it is created. See Change the Reclaim Policy of a PersistentVolume.
reference:
https://kubernetes.io/docs/concepts/storage/persistent-volumes/
Related
I have registered the snapshot repository and have been able to create snapshots of the cluster for a pod. I have used a mounted persistent volume as the "shared file system repository" as the backup storage.
However in a production cluster with multiple nodes, it is required that the shared file system is mounted for all the data and master nodes.
Hence I would have to mount the persistent volume for the data nodes and the master nodes.
But Kubernetes persistent volumes don't have a "read write many" option. So can't mount it on all the nodes and hence am unable to register the snapshot repository. Is there a way to use persistent volumes as the backup snapshot storage for a production elastic search cluster in Google Kubernetes Engine?
Reading this, I guess that you are using a cluster created on your own and not GKE, since you cannot install agents on master nodes and workers will get recreated whenever there is a node pool update. Please make this clear since it can be misleading.
There are multiple volumes that allow multiple readers, such as cephfs, glusterfs and nfs. You can take a look at the different volume types on this
I have an m3 large. Although I can find the other EBS volumes associated with that instance in the Volumes Section.
But I am not able to find my 32GB SSD disk.
How can we take backup of this SSD?
It appears that you are referring to the Instance Store SSD volume that is provided as part of an m3.large Amazon EC2 instance.
Instance Store volumes are temporary (aka "ephemeral") and the content is lost when the instance is Stopped, Terminated or fails. Therefore, it is recommended only for temporary files and swap files. Be sure to copy off any data you wish to keep before the instance is Stopped.
Instance Store volumes are not the same as Elastic Block Store (EBS) volumes. While EBS provides a snapshot capability, this is not available for Instance Store volumes.
Instead, you must copy off any data you wish to keep via normal filesystem commands, or run traditional backup software. There is no snapshot-like capability available for Instance Store volumes.
In the Kubernetes example of Elasticsearch production deployment, there is a warning about using emptyDir, and advises to "be adapted according to your storage needs", which is linked to the documentation of persistent storage on Kubernetes.
Is it better to use a persistent storage, which is an external storage for the node, and so needs (high) I/O over network, or can we deploy a reliable Elasticsearch using multiple data nodes with local emptyDir storage?
Context: We're deploying our Kubernetes on commodity hardware, and we prefer not to use SAN for the storage layer (because it doesn't seem like commodity).
The warning is so that folks don't assume that using emptyDir provides a persistent storage layer. An emptyDir volume will persist as long as the pod is running on the same host. But if the host is replaced or it's disk becomes corrupted, then all data would be lost. Using network mounted storage is one way to work around both of these failure modes. If you want to use replicated storage instead, that works as well.
I ran into some issues with my EC2 micro instance and had to terminate it and create a new one in its place. But it seems even though the old instance is no longer visible in the list, it is still using up some space on my disk. My df -h is listed below:
Filesystem Size Used Avail Use%
/dev/xvda1 7.8G 7.0G 719M 91% /
When I go to the EC22 console I see there are 3 volumes each 8gb in the list. One of them is attached (/dev/xvda) and this one is showing as "in-use". The other 2 are simply showing as "Available"
Is the terminated instance really using up my disk space? If yes, how to free it up?
I have just solved my problem by running this command:
sudo apt autoremove
and a lot of old packages are going to be removed, for instance many files like this linux-aws-headers-4.4.0-1028
Amazon Elastic Block Storage (EBS) is a service that provides virtual disks for use with Amazon EC2. It is network-attached storage that persists even when an EC2 instance is stopped or terminated.
When launching an Amazon EC2 instance, a boot volume is automatically attached to the instance. The contents of the boot volume is copied from an Amazon Machine Image (AMI), which can be chosen from a pre-populated list (including the ability to create your own AMI).
When an Amazon EC2 instance is Stopped, all EBS volumes remain attached to the instance. This allows the instance to be Started with the same configuration as when it was stopped.
When an Amazon EC2 instance is Terminated, EBS volumes might or might not be deleted, based upon the Delete on Termination setting of each volume:
By default, boot volumes are deleted when an instance is terminated. This is because the volume was originally just a copy of an AMI, so there is unlikely to be any important data on the volume. (Hint: Don't store data on a boot volume.)
Additional volumes default to "do not delete on termination", on the assumption that they contain data that should be retained. When the instance is terminated, these volumes will remain in an Available state, ready to be attached to another instance.
So, if you do not require any content on your remaining EBS volumes, simply delete them. In future, when launching instances, keep an eye on the Delete on Termination setting to make the clean-up process simpler.
Please note that the df -h command is only showing currently-attached volumes. It is not showing the volumes in Available state, since they are not visible to that instance. The concept of "Disk Space" typical refers to the space within an EBS volume, while "EBS Storage" refers to the volumes themselves. So, the 7GB of the volume that is used is related to that specific (boot) volume.
If you are running out of space on an EBS volume, see: Expanding the Storage Space of an EBS Volume on Linux. Expanding the volume involves:
Creating a snapshot
Creating a new (bigger) volume from the snapshot
Swapping the disks (requiring a Stop/Start if you are swapping a boot volume)
These 2 steps add an extra hard drive to your EC2 and format it for use:
Attach an extra hard drive (EBS: Elastic Block Storage) to an EC2
Format an EBS drive attached to an EC2
Here's pricing info. Free Tier includes 30GB. Afterward it's $1.25/month for 10GB on a General Purpose SSD (gp2).
To see how much space you are using/need:
Check your current disk use/available in Linux with df -h.
Check the size of a directory in Linux with du -sh [path].
Why ephemeral disk isn't listed on (fdisk -l) when i create a instance on amazon ec2 from my previously created (AMI)?
You have two options to enable ephemeral storage on an instance.
Enable it at launch. Can be done in the console or command line tools.
Enable it with you register a snapshot as an AMI. By default it will not map ephemeral storage, this is something you have to explicitly enable.
In my case, I confused the ephemeral disk instance ID with the disk quantity, and added ephemeral disk instance 1, rather than ephemeral disk instance 0. m1.medium instances only support 1 ephemeral disk, and it MUST be ephemeral disk instance 0.