D-AV-DY-23 Practice Questions

The Avamar Procedure Generator (APG) is the official and mandatory Dell tool for creating a complete, customized, step-by-step guide for implementing an Avamar server. It prompts the user for specific details about the environment, such as hardware model, software version, and network configuration. It then generates a unique document containing all necessary pre-installation checks, installation tasks, and post-installation validation steps in the correct sequence. This ensures consistency, accuracy, and adherence to Dell's best practices for every deployment.

B. The Dell Backup System Sizer is a pre-sales and planning tool used to determine the correct size and model of an Avamar system, not to guide its implementation.

C. The TS-Kit Configuration Guide is a generic document. The APG provides a procedure that is specifically tailored to the customer's unique configuration.

D. The TS-Kit Test Plan is a document used for system validation and testing after the implementation is complete, not a guide for the implementation process itself.

1. Dell Avamar Virtual Edition 19.4 Installation and Upgrade Guide, P/N 302-006-121 REV 01, 2021, Page 10: "Use the Avamar Procedure Generator to generate customized installation procedures. The Avamar Procedure Generator is available on the Dell Support website."

2. Dell PowerProtect DP Series and IDPA 2.7.2 Procedure Generator Guide, 2021, Page 5: "The Procedure Generator is a tool that creates customized procedures for... new system installations, upgrades, and node additions." This shows the consistent purpose of procedure generators across Dell's backup portfolio.

The Avamar Gen4 hardware platform was offered in several node sizes. The smaller capacity nodes, 1.3 TB and 2.6 TB, were designed exclusively as single-node servers, suitable for smaller environments or remote office deployments. The larger capacity 3.9 TB and 7.8 TB nodes were designed as storage nodes for building scalable, high-capacity multi-node grids. These grids could be expanded by adding more of these storage nodes to meet growing data protection requirements.

A: The 1.3 TB node is a single-node server only and cannot be used in a multi-node Avamar grid configuration.

B: The 2.6 TB node is a single-node server only and is not designed for expansion into a multi-node grid.

C: The 2.6 TB node is a single-node server only, making this combination invalid for a multi-node configuration.

1. EMC Avamar Data Store Gen4 Hardware Guide (P/N 300-012-299 REV A06), Page 11, Table 1 "Avamar Data Store Gen4 models". This table explicitly lists the 1.3 TB and 2.6 TB models as "Single-node" and the 3.9 TB and 7.8 TB models as "Multi-node".

Avamar first tests each chunk’s compressibility. If the compressed size is 25 % (or more) smaller than the original, the chunk is compressed before its hash is calculated.

• 7 chunks compressible by 30 % (>25 %)

• 4 chunks compressible by 23 % (<25 %)

• 2 chunks compressible by 50 % (>25 %)

Therefore, 7 + 2 = 9 chunks are compressed prior to hashing.

A. 4 – only counts the chunks at 23 %; these are below the compression threshold.

B. 7 – ignores the two 50 %-compressible chunks that also meet the threshold.

D. 13 – assumes every chunk is compressed; those at 23 % are not.

1. Dell EMC “Avamar Deduplication and Compression Technical Note” (H12762-A), §3.2, p.6 – “Chunks are stored in compressed form only when the compressed size is ≤75 % of the original (≥25 % reduction).”

2. Dell EMC Avamar 7.0 System Administration Guide, p.120 – description of client-side chunk compression threshold prior to hash generation.

3. Dell Technologies “Avamar Product Architecture Overview” Rev C, p.14 – workflow diagram showing ‘Compress (if ≥25 % gain) → Hash’.

The avmaint config balancemin= command sets the minimum percentage difference in utilization between the most-full and least-full storage nodes required to trigger data balancing. The default value is typically 5%. By lowering this threshold to a small value like 2, an administrator instructs the system to initiate balancing even with a minor imbalance, effectively forcing a redistribution of data. The --avamaronly flag ensures the command applies only to the Avamar server processes.

B. balancemin=0 is not recommended as it would cause the balancer to run constantly, consuming system resources unnecessarily.

C. balancemin=1 is more aggressive than necessary and could also lead to excessive balancing activity for minimal gain.

D. balancemin=100 would effectively disable data balancing, as it is impossible for nodes to have a 100% utilization difference.

1. Dell Avamar 19.7 Administration Guide, Page 411, "avmaint config command". The guide describes the balancemin parameter's function in controlling the data balancing threshold.

2. Dell Technologies Knowledge Base Article 000019391, "Avamar: How to check and start GSAN data balancing". This article discusses using avmaint config balancemin to manage and initiate data balancing.

Dell EMC recommends limiting a single Avamar file-system client to about 5–10 million files so that the hash-generation, backup window, and checkpoint creation remain within acceptable SLA limits. This guideline is published in the Avamar best-practices documentation and is the principal sizing rule when planning client deployments.

B Database limits are expressed in GB per database instance, not a global 5 TB figure.

C 10 TB refers to aggregate capacity per Avamar server stripe, not per client.

D 500 GB is the recommended per-database limit for hot backups, not for generic client sizing.

1. Dell EMC Avamar 19.3 Best Practices Guide, “Client Performance Guidelines,” p. 34-35 (5–10 million file recommendation).

2. Dell EMC Avamar 7.5 Sizing Guidelines, §2.1.1 “File System Client Limits,” p. 12.

3. Dell EMC White Paper H16392, “Avamar Backup Performance,” p. 7-8.

The HFS (Hardware File System) check is a critical integrity check that runs during the daily maintenance window. To ensure a consistent and accurate scan of the data stripes on the storage nodes, the system must be in a relatively quiescent state. The HFS check process will not initiate if more than two backup or restore sessions are actively running on any single storage node in the Avamar grid. This threshold prevents active I/O operations from interfering with the integrity check.

A. The system allows for a small amount of activity; a single backup is permitted, so the threshold is higher than 1.

C. Three active backups on a node are considered too much activity for the HFS check to start safely, so it will wait.

D. Four active backups would present a significant workload on a node, preventing the HFS check from initiating.

1. Dell Avamar Administration Guide, Version 19.9, Page 141, "HFS check". The guide explicitly states, "The HFS check does not start if more than two backup/restore sessions are running on any data node."

2. Dell Avamar System Health Check and Monitoring Guide, Section "Daily Maintenance Tasks". This document details the preconditions for maintenance jobs, noting that hfscheck has a prerequisite check for active sessions and will pause if the count exceeds two per node.

Dell Avamar ensures high availability and data integrity through multiple layers of fault tolerance. RAID (Redundant Array of Independent Disks) protects against individual disk failures within a node. RAIN (Redundant Array of Independent Nodes) protects against the failure of an entire storage node by distributing data and parity across the grid. Checkpoints are validated point-in-time snapshots of the server's metadata, enabling rollback capabilities. Replication provides disaster recovery by copying backup data to a secondary Avamar system.

B. HFS check: HFS check (hfscheck) is a maintenance utility for checking file system integrity, not a built-in, continuous fault tolerance mechanism.

C. Asynchronous crunching: This is not a recognized Avamar fault tolerance term. Parity is a component of RAID and RAIN, not a separate mechanism.

D. HFS check: As stated previously, HFS check is a reactive maintenance tool, not a primary, proactive fault tolerance feature like the others listed.

- Dell Avamar 19.4 Administration Guide, Page 416, "Data protection". This section details the roles of Checkpoints, RAIN, and Replication in protecting the Avamar server.

- Dell EMC Avamar Data Store Gen4S Hardware Information Guide. This document describes the physical node architecture, which includes RAID-protected disks as a fundamental component.

- Dell Technologies White Paper: "Dell EMC Avamar—Data Protection and Recovery". This paper provides a detailed overview of Avamar's reliability features, including RAIN for node-level protection and replication for disaster recovery.

Checkpoint overhead is the amount of storage space required to maintain a consistent point-in-time map of the data on the Avamar grid. The primary factor impacting this overhead is the system's daily change rate. A higher change rate means more new data chunks are added and more existing chunks are referenced or dereferenced between checkpoints. This results in a larger volume of metadata changes that must be recorded in the new checkpoint, thereby increasing its size and the associated storage overhead.

B. Frequency of client backups: This can influence the change rate, but the change rate itself is the direct factor. Frequent backups of static data would have minimal impact.

C. Whether backups succeed everyday: Failed backups would lead to a lower change rate for that day, thus decreasing the checkpoint overhead, but the rate of change is the fundamental driver.

D. Size of the grid and licensed amount: A larger grid has more capacity for overhead, but the actual overhead generated is a function of data churn (change rate), not the system's physical or licensed size.

1. Dell Avamar System Administration Guide 19.7, Page 113, "Checkpoints": "A checkpoint is a consistent, point-in-time view of the entire set of data on the GSAN... The amount of space that checkpoints consume is proportional to the daily rate of data change on the Avamar server."

2. Dell Avamar Technical and Architectural Deep Dive (White Paper), "Avamar Architecture" section: The document explains that checkpoints record the state of stripes. The number of new or modified stripes is directly related to the amount of new, changed data ingested since the last checkpoint.

During a backup or restore operation, the Avamar client process (avtar) must connect to the gsan (Global SAN) service running on the Avamar data nodes to transfer data. The standard TCP port used for this client-to-server data transfer is 29000. All modern Avamar client-to-server communication over this port is encrypted by default using Transport Layer Security (TLS) to ensure data confidentiality and integrity while in transit.

A. 27000: This port is used by the Avamar Administrator GUI to connect to the Management Console Server (MCS) for system administration.

B. 28001: This is the default listener port on the Avamar client for the avagent service, which the server uses to initiate on-demand backups.

C. 28002: This is the secure port used by clients to register and communicate with the MCS for activation and policy updates, not for data transfer.

1. Dell Avamar 19.4 Security Configuration Guide, Page 16, Table 2 "Avamar server firewall ports". The table lists TCP Port 29000 with the description "Client backup/restore" for connections from the Client to the Storage Node (gsan).

The factory-supplied Default Daily schedule opens the backup window each day at 20:00 and closes it at 08:00 server time, providing a 12-hour window unless the administrator changes it.

A. 6 hours is not the preset window in the Default Daily schedule.

B. 8 hours understates the default window length.

C. 10 hours is not used in any default Avamar schedule.

1. Dell EMC Avamar Administration Guide v19.4, Doc ID 302-005-608, “Schedules,” p. 110: “Default Daily: backup window 20:00–08:00.”

2. Dell EMC Education Services, Avamar Operational Best Practices White Paper, H17026, §3.2: “By default Avamar allocates a 12-hour backup window (20:00-08:00).”