Avamar Capacity limits and thresholds

80% — capacity warning issued

• When server utilization reaches 80%, a pop-up notification informs you that the server has consumed 80% of its available storage capacity. Avamar Enterprise Manager capacity state icons are yellow.

 95% — the “health check limit”

• This is the amount of storage capacity that can be consumed and still have a “healthy” server. Backups that are in progress are allowed to complete, but all new backup activity is suspended. A notification is sent in the form of a pop-up alert when you log in to Avamar Administrator. That system event must be acknowledged before future backup activity can resume. 

100% — the “server read-only limit”

• When server utilization reaches 100% of total storage capacity, it automatically becomes read-only.

Avamar Lexicon

dataset: Avamar datasets are a list of directories and files to back up from a client. Assigning a
dataset to a client or group enables you to save backup selections.

group policy: Group policy controls backup behavior for all members of the group unless you override these settings at the client level. It is comprised of: Datasets, Schedules and Retention Policies.

Avamar client files f_cache.dat and p_cache.dat

At the beginning of a backup, the Avamar client process, avtar, loads two cache files from
the var directory into RAM

•  f_cache.dat (a.k.a "File Cache")

• p_cache.dat (a.k.a "Hash Cache")

The f_cache.dat cache file stores a 20-byte SHA-1 hash of the file attributes, and is used to
quickly identify which files have previously been backed up to the Avamar server.

The p_cache.dat hash cache stores the hashes of the chunks and composites that have
been sent to the Avamar server. The hash cache is used to quickly identify which chunks
or composites have previously been backed up to the Avamar server. The hash cache is
very important when backing up databases.

By default, the maximum File Cache size can be 1/8 of the RAM and the maximum Hash Cache size will 1/16 of the RAM.

Because the avtar program is a 32-bit application, the maximum file cache size that avtar
can use is limited to less than 2 GB. In an example where a client has 4 GB of RAM, the
maximum size of the file cache is 352 MB.
Each entry in a file cache comprises a 4-byte header plus two 20-byte SHA-1 hashes (44
bytes total):

• SHA-1 hash entry of the file attributes. The file attributes include: file name, file path, modification time, file size, owner,group, and permissions.

•  SHA-1 hash entry for the hash of the actual file content, independent of the file attributes.

Avamar Gen4 nodes cabling

Utility node Cabling:

Storage Node Cabling:

GB1==eth0
GB2==eth1
GB3==eth2
GB4==eth3


GB1==eth0------>Customer_Switch (BOND1)
GB2==eth1------>Switch_A (BOND0)
GB3==eth2------>Customer_Switch (BOND1)
GB4==eth3------>Switch_B (BOND0)


Basic networking configuration
ADS Gen4 systems follow these configuration principles:
• All nodes are plugged in to internal dedicated ADS switches through Gb2
(eth1) and Gb4 (eth3) as primary and secondary interfaces of bond1.
• The internal network is a redundant, high availability, fault-tolerant network connecting all nodes in the cluster for RAIN, rebuilding, and maintenance functions. It carries all Avamar internal operations and data management traffic.
• All nodes are also plugged in to an external customer switch through Gb1 (eth0). If high availability is desired, all nodes can also be connected to a different customer switch through Gb3 (eth2), in which case eth0 and eth2 would be primary and secondary interfaces of bond0.
• All networking ports on all nodes are bonded in pairs, by default.
• Gb1 (eth0) and Gb3 (eth2) port bonding on storage nodes can be broken to facilitate incoming replication, which is delivered directly to storage nodes, or for node management. If this bond is broken, high availability backup capability is not possible. Refer to ADS Gen4 replication (page 83)
• The utility node can also be plugged in to an external customer switch for optional outgoing replication and node management through its additional four network interfaces, Gb5 (eth4), Gb6 (eth5), Gb7 (eth6), and Gb8 (eth7). These NICs are also bonded in pairs for high availability configuration.
• The internal dedicated ADS switches are not connected to the customer network. They have redundant power to support fault tolerance. Network configurations supported by ADS Gen4
AVAMAR DATA STORE NETWORKING EMC AVAMAR DATA STORE • GEN4 MULTI-NODE SYSTEM INSTALLATION GUIDE 47
• If the customer’s network environment is segregated using VLANs, corresponding VLANs must be configured on the storage nodes. Consult with the customer’s network administrator to obtain a list of VLAN IDs to configure when running the dpnnetutil utility.
• For ADS networks that do not require advanced configuration like VLAN support, the network configuration workflow included in the standard software installation process is used. There is no need to define IP addresses in advance except for the utility node. See Installing Avamar server software (page 98). In advanced configuration scenarios (running dpnnetutil), all nodes must have an initial IP address that can be accessed from the utility node by SSH command. That means a combination of the following conditions: being properly kickstarted and having SSH connectivity between each other.
• All node ports autonegotiate to 1 Gb Ethernet (full duplex) on the external customer network.
• These networking principles end previous ADS system requirements for port trunking, spanning tree or bonding between the ADS and customer switches.
• All connections to the customer network are standard leaf connections directly with individual nodes.
• The external customer network switch can be shared with other
applications. See ADS Gen4 hardware (page 180) for descriptions and images related to node and switch networking components. See the following images for further clarification of possible ADS Gen4 networking configurations.