W E K A
4.0
4.0
  • WEKA v4.0 documentation
  • WEKA System Overview
    • About the WEKA system
    • SSD capacity management
    • Filesystems, object stores, and filesystem groups
    • Weka networking
    • Data lifecycle management
    • Weka client and mount modes
    • Weka containers architecture overview
    • Glossary
  • Getting Started with Weka
    • Quick installation guide
    • Manage the system using the Weka CLI
    • Manage the system using the Weka GUI
    • Run first IOs with WekaFS
    • Getting started with Weka REST API
  • Planning & Installation
    • Prerequisites for installation
    • Weka installation on bare metal
      • Planning a Weka System Installation
      • Prepare the system for Weka installation
        • SR-IOV enablement
      • Obtain the Weka software installation package
      • Weka cluster installation
      • WEKA legacy system installation process
      • Add clients
    • Weka installation on AWS
      • Self-service portal
      • CloudFormation template generator
      • Deployment types
      • AWS outposts deployment
      • Supported EC2 instance types
      • Add clients
      • Auto scaling group
      • Troubleshooting
  • Performance
    • Weka performance tests
      • Test environment details
  • WekaFS Filesystems & Object Stores
    • Manage object stores
      • Manage object stores using the GUI
      • Manage object stores using the CLI
    • Manage filesystem groups
      • Manage filesystem groups using the GUI
      • Manage filesystem groups using the CLI
    • Manage filesystems
      • Manage filesystems using the GUI
      • Manage filesystems using the CLI
    • Attach or detach object store buckets
      • Attach or detach object store bucket using the GUI
      • Attach or detach object store buckets using the CLI
    • Advanced data lifecycle management
      • Advanced time-based policies for data storage location
      • Data management in tiered filesystems
      • Transition between tiered and SSD-only filesystems
      • Manual fetch and release of data
    • Mount filesystems
    • Snapshots
      • Manage snapshots using the GUI
      • Manage snapshots using the CLI
    • Snap-To-Object
      • Manage Snap-To-Object using the GUI
      • Manage Snap-To-Object using the CLI
    • Quota management
  • Additional Protocols
    • NFS
      • Manage NFS networking using the GUI
      • Manage NFS networking using the CLI
    • SMB
      • Manage SMB using the GUI
      • Manage SMB using the CLI
    • S3
      • S3 cluster management
        • Manage the S3 service using the GUI
        • Manage the S3 service using the CLI
      • S3 buckets management
        • Manage S3 buckets using the GUI
        • Manage S3 buckets using the CLI
      • S3 users and authentication
        • Manage S3 users and authentication using the CLI
        • Manage S3 service accounts using the CLI
      • S3 rules information lifecycle management (ILM)
        • Manage S3 rules using the CLI
      • Audit S3 APIs
        • Configure audit webhook using the GUI
        • Configure audit webhook using the CLI
        • Example: How to use Splunk to audit S3
      • S3 supported APIs and limitations
      • S3 examples using boto3
  • Operation Guide
    • Alerts
      • Manage alerts using the GUI
      • Manage alerts using the CLI
      • List of alerts and corrective actions
    • Events
      • Manage events using the GUI
      • Manage events using the CLI
      • List of events
    • Statistics
      • Manage statistics using the GUI
      • Manage statistics using the CLI
      • List of statistics
    • System congestion
    • Security management
      • Obtain authentication tokens
      • KMS management
        • Manage KMS using the GUI
        • Manage KMS using the CLI
      • TLS certificate management
        • Manage the TLS certificate using the GUI
        • Manage the TLS certificate using the CLI
      • CA certificate management
        • Manage the CA certificate using the GUI
        • Manage the CA certificate using the CLI
      • Account lockout threshold policy management
        • Manage the account lockout threshold policy using GUI
        • Manage the account lockout threshold policy using CLI
      • Manage the login banner
        • Manage the login banner using the GUI
        • Manage the login banner using the CLI
    • User management
      • Manage users using the GUI
      • Manage users using the CLI
    • Organizations management
      • Manage organizations using the GUI
      • Manage organizations using the CLI
      • Mount authentication for organization filesystems
    • Expand and shrink cluster resources
      • Expand and shrink overview
      • Workflow: Add a backend host
      • Expansion of specific resources
      • Shrink a Cluster
    • Background tasks
    • Upgrade Weka versions
  • Billing & Licensing
    • License overview
    • Classic license
    • Pay-As-You-Go license
  • Support
    • Prerequisites and compatibility
    • Get support for your Weka system
    • Diagnostics management
      • Traces management
        • Manage traces using the GUI
        • Manage traces using the CLI
      • Protocols debug level management
        • Manage protocols debug level using the GUI
        • Manage protocols debug level using the CLI
      • Collect and upload diagnostics data
    • Weka Home - The Weka support cloud
      • Local Weka Home overview
      • Local Weka Home deployment
      • Set the Local Weka Home to send alerts or events
      • Download the Usage Report or Analytics
  • Appendix
    • Weka CSI Plugin
    • Set up the Weka-mon external monitoring
    • Set up the SnapTool external snapshots manager
  • REST API Reference Guide
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On this page
  • Raw capacity
  • Net capacity
  • Stripe width
  • Protection level
  • Failure domains (optional)
  • Hot spare
  • Weka filesystem overhead
  • Provisioned capacity
  • Available capacity
  • Deductions from raw capacity to obtain net storage capacity
  • The formula for calculating SSD net storage capacity
  1. WEKA System Overview

SSD capacity management

Understand the key terminologies relating to Weka system capacity management and the formula for calculating the Weka system net data storage capacity.

Raw capacity

Raw capacity is the total capacity on all the SSDs assigned to a Weka system cluster, e.g., 10 SSDs of 1 terabyte each have a total raw capacity of 10 terabytes. This is the total capacity available for the Weka system. This will change automatically if more hosts or SSDs are added to the system.

Net capacity

Net capacity is the amount of space available for user data on the SSDs in a configured Weka system. It is based on the raw capacity minus the Weka filesystem overheads for redundancy protection and other needs. This will change automatically if more hosts or SSDs are added to the system.

Stripe width

The stripe width is the number of blocks that share a common protection set, which can range from 3 to 16. The Weka system has distributed any-to-any protection. Consequently, in a system with a stripe width of 8, many groups of 8 data units spread on various hosts protect each other (rather than a group of 8 hosts forming a protection group). The stripe width is set during the cluster formation and cannot be changed. Stripe width choice impacts performance and space.

Note: If not configured, the stripe width is set automatically to #Failure Domains - Protection Level

Protection level

The protection level is the number of additional protection blocks added to each stripe, which can be either 2 or 4. A system with a protection level of 2 can survive 2 concurrent failures, while system data with a protection level of 4 is protected against any concurrent 4 host/disk failures, and its availability is protected against any 4 concurrent disk failures or 2 concurrent host failures. A large protection level has space and performance implications. The protection level is set during the cluster formation and cannot be changed.

Note: If not configured, the data protection drives in the cluster stripes are automatically set to 2.

Failure domains (optional)

A failure domain is a group of Weka hosts, all of which can fail concurrently due to a single root cause, such as a power circuit or network switch failure. A cluster can be configured with explicit or implicit failure domains. For a system with explicit failure domains, each group of blocks that protect each other is spread on different failure domains. For a system with implicit failure domains, the group of blocks is spread on different hosts and each host is a failure domain. Additional failure domains can be added, and new hosts can be added to any existing or new failure domain.

Note: This documentation relates to a homogeneous Weka system deployment, i.e., the same number of hosts per failure domain (if any), and the same SSD capacity per host. For information about heterogeneous Weka system configurations, contact the Weka Support Team.

Hot spare

A hot spare is the number of failure domains that the system can lose, undergo a complete rebuild of data, and still maintain the same net capacity. All failure domains are always participating in storing the data, and the hot spare capacity is evenly spread within all failure domains.

The higher the hot spare count, the more hardware required to obtain the same net capacity. On the other hand, the higher the hot spare count, the more relaxed the IT maintenance schedule for replacements. The hot spare is defined during cluster formation and can be reconfigured at any time.

Note: If not configured, the hot spare is automatically set to 1.

Weka filesystem overhead

After deducting the capacity for the protection and hot spares, only 90% of the remaining capacity can be used as net user capacity, with the other 10% of capacity reserved for the Weka filesystems. This is a fixed formula that cannot be configured.

Provisioned capacity

The provisioned capacity is the total capacity assigned to filesystems. This includes both SSD and object store capacity.

Available capacity

The available capacity is the total capacity that can be used for the allocation of new filesystems, which is net capacity minus provisioned capacity.

Deductions from raw capacity to obtain net storage capacity

The net capacity of the Weka system is obtained after the following three deductions performed during configuration:

  1. Level of protection required, i.e., the amount of storage capacity to be dedicated to system protection.

  2. Hot spare(s), i.e., the amount of storage capacity to be set aside for redundancy and to allow for rebuilding following a component failure.

  3. Weka filesystem overhead, in order to improve overall performance.

The formula for calculating SSD net storage capacity

For Example:

Scenario 1: A homogeneous system of 10 hosts, each with 1 terabyte of Raw SSD Capacity, 1 hot spare, and a protection scheme of 6+2.

SSDNetCapacity=10TB∗(10−1)/10∗6/(6+2)∗0.9=6.075TBSSD Net Capacity = 10 TB * (10-1) / 10 * 6/(6+2) * 0.9 = 6.075 TBSSDNetCapacity=10TB∗(10−1)/10∗6/(6+2)∗0.9=6.075TB

Scenario 2: A homogeneous system of 20 hosts, each with 1 terabyte of Raw SSD Capacity, 2 hot spares, and a protection scheme of 16+2.

SSDNetCapacity=20TB∗(20−2)/20∗16/(16+2)∗0.9=14.4TBSSD Net Capacity = 20 TB * (20-2) / 20 * 16/(16+2) * 0.9 = 14.4 TBSSDNetCapacity=20TB∗(20−2)/20∗16/(16+2)∗0.9=14.4TB
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Last updated 3 years ago