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USING CONTAINER-NATIVE STORAGE:MYTHS AND BEST PRACTICESHow to Care for Your Storage
José A. RiveraSenior Software Engineer2018.04.10
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OVERVIEW
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OVERVIEWPlatform-agnostic Storage
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Scalable (1000+ volumes)
Highly-Available(across availability zones)
Automated (Dynamic Provisioning)
Integrated(installs with / runs on OpenShift)
OPENSHIFT NODE 2 OPENSHIFT NODE 3
OPENSHIFT NODE 1
RHGS Container RHGS Container
OPENSHIFT NODE 4
MASTERAPP Container APP Container
APP CONTAINER
RHGS Container
OVERVIEWContainer-Native Storage
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“A request for storage”
Provider: ABCCapacity: 10 GiBFeatures: XYZ
PersistentVolumeClaim
“A provider of storage”
Provider URL: …Credentials: …Options: ...
StorageClass
“Provisioned Storage”
Name: …Size: …AccessMode: ...
PersistentVolume
APPLICATION POD(S)
“sets up”
“submits” “submitted to” “creates”
Storage Backend
“instructs” “provisions”
“mounted by”
OVERVIEWDynamic Provisioning
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MYTHS
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MYTHSCollocation means increased performance
MYTH:Collocating my application pods with my storage pods will increase storage I/O performance.
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MYTHSCollocation means increased performance
MYTH:Collocating my application pods with my storage pods will increase storage I/O performance.
FACT: Only for read-only use cases, and not a significant amount.
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MYTHSStorage should be isolated
MYTH:Storage nodes should only host CNS pods.
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MYTHSStorage should be isolated
MYTH:Storage nodes should only host CNS pods.
FACT: For the vast majority of cases, storage nodes can be treated like any other app or infrastructure node.
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MYTHSSplit devices between multiple clusters
MYTH:I can isolate different types of devices on the same node in multiple CNS clusters.
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MYTHSSplit devices between multiple clusters
MYTH:I can isolate different devices on the same node in multiple CNS clusters.
FACT: A given storage node may only run one RHGS pod, and thus can only be part of a single cluster.
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MYTHSIsolate volume types
MYTH:I should isolate different types of storage volumes into their own clusters.
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MYTHSIsolate volume types
MYTH:I should isolate different types of storage volumes into their own clusters.
FACT: A single CNS cluster can provide a variety of volume types.
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BEST PRACTICES
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BEST PRACTICESStorage node specs
Each storage node should meet the following specifications:
● MEMORY: 8 GB of RAM + 30 MB of RAM per active volume○ This counts all volumes in the cluster, even if a given node is not hosting any
data for some of those volumes● CPU: No technical minimum, recommended minimums are:
○ Intel Xeon Nehalem-Ex or equivalent○ Dual socket server○ Quad-core processors
These minimums account for OS needs and other applications running on the same node.
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BEST PRACTICESCluster size
Cluster size is heavily dependent on anticipated workloads, but there are some recommended minimums and sizing guidelines:
● Technical minimum of 3 nodes using default configuration● Recommended minimum of 4 nodes to increase failure tolerance● Two separate clusters are recommended, one for user applications and one for
infrastructure applications● Recommended maximum of 1000 concurrent volumes per 3-node cluster
○ Max does not scale linearly with additional nodes○ Recommended to add additional clusters to support > 1000 volumes
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BEST PRACTICESIncreasing capacity
CNS provides various ways to increase storage capacity:
● Add more devices to existing nodes● Add more nodes to existing clusters
○ Maximum 128 nodes per cluster● Add more clusters to existing CNS installations
○ Can be immediately used by existing StorageClasses● Deploy additional CNS installations
○ Requires namespace isolation
Rough maximum of 17 Petabytes of total storage capacity using three-way replicated volumes.
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QUESTIONS?
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THANKS!
José A. Rivera <jarrpa@redhat.com> @jarrpa
Container-Native Storagehttps://www.redhat.com/en/technologies/storage/use-cases/container-native-storage
OpenShift Advanced Installer - GlusterFS Documentationhttps://docs.openshift.com/container-platform/3.9/install_config/persistent_storage/persistent_storage_glusterfs.html
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