Nvs Cards; Line Modules - Juniper E SERIES BROADBAND SERVICES ROUTERS 11.3.X - ERX HARDWARE GUIDE REV 26-9-2010 Hardware Manual

Line Modules

Copyright © 2010, Juniper Networks, Inc.

NVS Cards

If you have two SRP modules installed in a system, you can use NVS cards of different
capacities on the SRP modules. The effective capacity of the higher-capacity NVS card
will equal that of the lower-capacity NVS card. For information about installing NVS
cards, see "Installing Modules" on page 31.
When you install new NVS cards or SRP modules, you must issue the synchronize
command to match the file system of the NVS card on the redundant SRP module with
the file system of the NVS card on the primary SRP module. (The NVS card on the
redundant SRP module will hereafter be referred to as the redundant NVS card; the NVS
card on the primary SRP module will hereafter be referred to as the primary NVS card.)
If the capacity of the primary NVS card is equal to or smaller than that of the redundant
NVS card, the system copies all the files from the primary NVS card to the redundant
NVS card. However, if the capacity of the primary NVS card exceeds that of the redundant
NVS card, the system creates an invisible synchronization reserve file on the primary NVS
card, provided that there is enough space for the file.
The purpose of the synchronization file is to prevent the creation of data that cannot fit
on the redundant NVS card. The file contains no useful data, and is not visible when you
view the files in NVS. The size of the file is equal to the difference in capacities of the two
NVS cards. For example, if the primary NVS card has a capacity of 224 MB and the
redundant NVS card has a capacity of 220 MB, the size of the synchronization file is 4 MB,
and only 220 MB of space is available on the primary NVS card.
If the primary NVS card does not have enough space to create the synchronization reserve
file, the synchronize command fails, and a warning message is displayed on the console.
To resolve this issue, either delete unwanted files from the primary NVS card or replace
the redundant NVS card with a higher-capacity NVS card.
NOTE: This section applies to ERX7xx and ERX14xx models only. ERX310
routers do not offer line module redundancy.
ERX7xx and ERX14xx models support line module redundancy for several line modules.
For details about which line modules support redundancy, see the ERX Module Guide. In
this scheme, an extra line module in a group of identical line modules provides redundancy
in case of line module failure. To use this feature, you need a:
Spare line module
Redundancy midplane
Redundancy I/O module
A redundancy midplane can cover 3–6 slots. It provides additional connectivity that
enables the spare line module to take control of the I/O module associated with any
failed line module in the redundancy group. The spare I/O module provides connectivity
from the spare line module to the redundancy midplane.
Chapter 1: ERX Overview
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