Mastering Quota Management in Amazon FSx for NetApp ONTAP

[Shaun_P]

Introduction

Whether you are a global enterprise or small business, the ability to control and understand your data footprint is vital to operational efficiency and cost management. Quotas in Amazon FSx for NetApp ONTAP file service (FSx for ONTAP) enable you to effortlessly track and regulate the disk space and number of files consumed by users, groups, or qtrees. Beyond quotas, this fully managed file service is equipped with the full suite of ONTAP’s popular data management capabilities, including instant snapshots, data tiering, and storage efficiencies. This blog will take you through a customer success story, take a deep dive into quotas, and share the best practices for quota management. It is the first instalment of a two-part series on quotas with FSx for ONTAP, paving the way for the second blog which will provide a technical walkthrough on how to enforce and test quotas, ensuring a holistic understanding of quota management.

Customer challenge

As part of its sustainability initiatives and its aim to achieve carbon neutrality, one of the largest integrated human resources companies based in Japan embarked on migrating its IT infrastructure to the cloud. Their on-premises filesystem, which served over 40,000 employees and hosted petabytes of data, posed a substantial migration challenge. It was imperative for the IT team to select a cloud storage solution that could not only meet their complex storage, management, and performance requirements but also enable the implementation of quotas as a critical tool for monitoring and managing data growth effectively.

Limitations of volumes

In a shared storage environment, it is important to ensure that no individual or application monopolizes the storage resources to maintain system performance and availability. The great news is that resource quota management on ONTAP is policy driven and can be fully automated, freeing up your IT staff to focus on your higher-level business needs.

For organizations utilizing FSx for ONTAP, the default service limit of 500 volumes per filesystem may become a constraint as data demands grow, especially in complex environments with multiple business units. While it may be possible to request for higher volume limits, an effective alternative is the strategic use of qtrees. Qtrees function as logical containers within volumes, with each volume capable of hosting up to 4,995 individual qtrees with tailored permissions and security styles. By optimizing the use of qtrees, organizations can sidestep the need for service limit increases, as they provide a structured, scalable way to manage data access and organize storage efficiently. Qtrees not only facilitate refined quota management but also enable a more sophisticated data management approach within FSx for ONTAP, turning existing storage volumes into versatile data containers.

Types of quotas

Quotas provide a way to restrict and track the disk space and number of files used by specified targets (user, group, or qtree) in a volume or qtree.

Figure 1. Types of quota targets

To implement user or group quotas in ONTAP, the system must be able to resolve the specified username or group. This can be done by defining the user or group locally on the Storage Virtual Machine, or by using an external name service such as Active Directory, LDAP, or NIS. User and group quotas are essential in scenarios where multiple users or groups share the same volume or qtree, as they allow administrators to report or enforce capacity or file count limits on a per-user or per-group basis. Similarly, tree quotas are used to report and enforce capacity or file count limits for qtrees within a volume.

There are four types of quotas that can be applied on a target: default, tracking, explicit, and derived.

1. Default Quotas: Default quotas are applied to all applicable targets within a volume or qtree if a specific quota for a target is not explicitly set.
   • Example: to ensure that all users are each limited to 10 GB of disk space on the ProjectFiles volume, an administrator can set a default user quota of 10 GB. This quota is then automatically applied to all users and ensures that every user in the ProjectFiles volume can only use up to 10 GB of disk space. The default user quota simplifies management by imposing a uniform limit across the board to prevent any single user from consuming excessive storage.

2. Tracking Quotas: Tracking quotas are used for monitoring purposes and do not enforce any limits on disk space or file usage. They function similarly to default quotas in that they report on the usage of the specified targets at the volume or qtree level. This allows administrators to track usage without imposing restrictions.
   • Example: to monitor the storage usage of a project without restricting data growth, an administrator can set a tracking quota on all users in the ProjectFiles volume. This allows the IT team to gather usage data for analysis and future planning without impacting current operations.Figure 2. How default and tracking quotas are applied
3. Explicit Quotas: Explicit quotas are specific to a target and override default quotas.
   • Example: if a graphic designer requires more storage than other users, an administrator can set an explicit quota for user designer1 to have 50GB of disk space on the ProjectFiles volume, even though the default user quota is 10GB. This explicit quota ensures that designer1 has the necessary space for large design files, while other users remain subject to the default quota.Figure 3. How explicit quotas are applied
4. Derived Quotas: Derived quotas are automatically created by ONTAP based on default quotas. They inherit the limits and settings of the corresponding default quota and are applied to individual targets without the need for manual configuration. This allows administrators to “set-and-forget” quota polices as they will be inherited by users, groups and, qtrees in the following scenarios:
   1. A default tree quota on a volume will create derived default tree quotas for every qtree on the volume.
      • Example: an administrator wants to ensure that no project directory within a volume exceeds 50GB to prevent any single project from consuming excessive storage. A default tree quota of 50GB on the volume ProjectData is set and as a result, every qtree that is created under the ProjectData volume will have a derived default tree quota of 50GB without the need for individual tree quotas to be set.Figure 4. How derived quotas are applied in Scenario A

   2.  A default user or group quota will create derived default user or group quotas for every user or group that owns a file at the volume or qtree level.

      • Example: to control the amount of data each user can store, an administrator sets a default user quota of 10GB on the volume UserData. This default user quota will result in a derived user quota for every user that owns files within the UserData volume. If user sphua creates files in the volume, a derived user quota of 10GB will automatically apply to sphua without any additional configuration.Figure 5. How derived quotas are applied in Scenario B

   3.  A default user or group quota on a volume creates a derived default user or group quota on every qtree with an existing tree quota.

      • Example: On a volume DepartmentData that already has a tree quota for each department, an administrator sets a default user quota of 5GB to limit individual usage. With this default user quota in place, each qtree representing a department will have a derived default user quota. If the Finance qtree has its tree quota, every user within the Finance qtree will also have a derived default user quota of 5GB, ensuring that individual user consumption is regulated in addition to the overall department's storage caFigure 6. How derived quotas are applied in Scenario C

Types of quota limits

There are two primary types of quota limits: hard quotas and soft quotas. Hard quotas are stringent limits that, once reached, prevent further write operations to ensure the system does not exceed allocated resources. If a user attempts to write data that would surpass the hard limit, ONTAP denies the operation and issues a hard quota notification. The ‘Disk Limit’ and ‘Files Limit’ parameters are used to set these hard quotas.

On the other hand, soft quotas are advisory and are designed to send notifications when resource usage approaches the set limits. These warnings allow administrators to take pre-emptive action to manage storage before reaching the quota. Unlike hard quotas, soft quotas do not block data access operations when limits are reached. The settings for creating soft quotas include the ‘Threshold Disk Limit’, ‘Soft Disk Limit’, and ‘Soft Files Limit’ parameters. Administrators often set the threshold disk limit slightly below the hard disk limit so that the threshold provides a “final warning” before writes start to fail.

Quota events and notifications

Quota events and notifications are a critical component of FSx for ONTAP storage management, providing administrators with the tools needed to enforce storage policies and stay informed about storage consumption. When a quota limit is exceeded, ONTAP's response is determined by the type of limit that has been set—be it hard, threshold, or soft.

ONTAP generates notifications for the following quota-related events:

• When a hard quota is reached, meaning there is an attempt to exceed the set limit, preventing further write operations.
• When a soft quota is exceeded, which serves as a warning that the set limit has been surpassed.
• When a soft quota is no longer exceeded, indicating that the usage has dropped below the set threshold.
• When a threshold quota is exceeded, acting as a preemptive alert before the hard quota limit is reached.

‼️ Note: At the time of publication (June 2024, FSx for ONTAP version 9.13.1), quota notifications are currently limited to hard tree quotas events (wafl.quota.qtree.exceeded and wafl.quota.qtree.correct). Notifications for hard user and group quotas, as well as for soft quota events, do not currently generate notifications. Notifications for these quota events will be progressively added in future updates. ‼️

By default, quota-related events trigger notifications to the Events Management System, which can also be configured to forward these notifications to Syslog servers. This setup allows for a real-time, centralized logging solution, offering administrators a comprehensive view of the storage system's status. Key details such as event names, severity, potential causes, log messages, and corrective actions in these notifications enables administrators to respond swiftly and effectively, ensuring the system's health and adherence to quota policies.

Customer solution

For the integrated human resources company, the transition to Amazon FSx for NetApp ONTAP was a strategic move that aligned with their sustainability goals and the need for cost-effective cloud storage management. The company leveraged the native ONTAP features such as qtrees, which provided a methodical way to manage storage capacity for their extensive user base. Qtrees allowed for the setting of specific quotas, thereby optimizing the utilization of storage resources and preventing overconsumption.

Additionally, the automatic data tiering capability of FSx for ONTAP played a cruial role in their cost management strategy. By automatically transitioning less frequently accessed data to a more economical capacity pool tier, they were able to significantly reduce costs while ensuring high performance for active datasets. This tiering system, combined with storage efficiency features like compression and deduplication, resulted in substantial storage savings and enhanced overall system performance.

The IT team's decision to adopt FSx for ONTAP was further reinforced by the ease of managing shared file storage at scale, with the added benefits of high availability and robust data protection mechanisms. Ultimately, FSx for ONTAP provided a fully managed solution that met their complex storage requirements, enabling the company to achieve its sustainability objectives and demonstrate a commitment to efficient resource utilization.

Best practices for quota management

Effective quota management is essential for ensuring that storage resources are utilized efficiently and do not adversely affect system performance or user experience. To guide storage administrators, the following best practices should be considered:

1. Set reasonable and achievable quotas.
   • It is crucial to set quotas that are attainable and aligned with the needs of users and applications. Quotas set too low may deplete space quickly, potentially degrading performance. Conversely, excessively high quotas can lead to underutilized resources, wasting valuable storage capacity.
2. Monitor and adjust quotas regularly.
   • Regularly monitor and adjust quotas to reflect changing usage patterns and business objectives. This proactive approach allows administrators to identify trends and make informed decisions that support the evolving needs of the organization.
3. Use a combination of user, group, and tree quotas.
   • Implementing a mix of user, group, and tree quotas allows for nuanced management of storage. Individual user quotas can limit personal usage, group quotas can manage collective consumption, and tree quotas can control usage within specific qtrees.
4. Test and validate quota settings.
   • Before applying quotas in a production environment, testing and validation are necessary to confirm they function as intended. This helps avoid potential issues like application underperformance or data loss due to accidental file deletions.
5. Consider the impact of quotas on applications.
   • Assess the impact of quotas on applications and workflows. Some applications may require more space or could be negatively impacted by restrictive quotas, leading to performance bottlenecks. Understanding these implications is vital for maintaining optimal application performance.
6. Document and communicate quota policies.
   • Clear documentation and communication of quota policies ensure that everyone understands the limits and their responsibilities. This can help prevent confusion and ensure adherence to the set quotas.

Conclusion

In conclusion, quota management within FSx for ONTAP is crucial for operational efficiency and cost management. This blog post, the first in a two-part series, has provided an overview of quota management and shared insights into its practical benefits. With the foundational knowledge from this post, you are now well-prepared to dive into the technical walkthrough, where you will have the opportunity to apply these principles and see firsthand the impact of quotas on your FSx for ONTAP environment. The second instalment offers a technical walkthrough with step-by-step instructions on enforcing and testing quotas.

Together, these resources offer a comprehensive understanding of how to effectively implement and manage quotas within your FSx for ONTAP environment. I encourage you to explore both the overview and the technical walkthrough to equip yourself with the knowledge and tools necessary to maintain a well-organized, cost-effective storage system.

Shaun Phua is a Cloud Solutions Engineer at NetApp specializing in Amazon FSx for NetApp ONTAP file services. In this role, Shaun collaborates with customers to design and build secure, scalable, hybrid cloud storage solutions across their on-premises datacenters and the cloud. Outside of work, Shaun loves travelling and trying new foods 🥘 and drinks 🍻!