2.3.1. Setting Up NTP for Time Synchronization
DX Storage clusters are capable of synchronizing their nodes' clocks internally. However, Dell
strongly recommends you use one or more trusted network time protocol (NTP) servers whenever
they are available. This assures that a cluster's clock is in sync with the clocks of the client
machines. If you boot DX Storage from a CSN, the CSN provides NTP services for all DX Storage
nodes and no further configuration is required.
If one or more trusted NTP servers are available, configure DX Storage to use them by setting the
timeSource parameter in the node or cluster configuration files. The value of the timeSource
parameter is a list of one or more NTP servers separated by spaces. An example follows:
timeSource = 10.20.40.21 10.20.50.31
If your DX Storage nodes are able to resolve host names, you can use
recommends you use pool servers that are close to your servers' time zone as discussed
ntp.org help
page. (To view the page in a language other than English, start with
click the "how do I use?" link.)
The following example shows how to use United States-based NTP servers:
timeSource = 0.us.pool.ntp.org 1.us.pool.ntp.org 2.us.pool.ntp.org
Note
NTP version 3 has design limitation that causes time to wrap in the year 2036. If a
computer's BIOS clock is set beyond this wrap point, NTP cannot correct the time. Make
sure that all BIOS clocks are set to a date prior to 2036 before booting DX Storage.
Alternatively, you can use NTP version 4.
2.3.2. Setting Up DNS for Name Resolution
The domain name service (DNS) is used to resolve host names into IP addresses. While DNS is
not required for DX Storage nodes to communicate with each other, DNS can be very useful for
client applications to reach the cluster. If you use named objects, DNS is one method you can use to
enable access to objects over the Internet.
Although client applications can initiate first contact with any node in the DX Storage cluster – even
choosing to access the same node every time - Dell recommends that the node of first contact be
evenly distributed around the cluster.
Basic options follow:
• Define multiple DNS entries ("A" or "CNAME" records) that each specify the IP address of the
same DX Storage node of first contact.
• Use multiple IP addresses for a DNS entry to create a DNS round-robin which provides client
request balancing.
Consult your DNS software documentation for guidance on using "A" records and "CNAME" (alias)
records.
The following example shows the entries for three node IP addresses tied to one name. This is the
configuration file format of the widely used ISC Bind Daemon.
DX Storage
0
IN A
192.168.1.102
Copyright © 2010 Caringo, Inc.
All rights reserved
0
IN A
192.168.1.101
8
NTP pool
servers. Dell
on the
www.ntp.org
and
Version 5.0
December 2010
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