Node Recovery

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Node Recovery

• Day 3, Session 6
• MetaArchive Distributed Digital Preservation
  Workshop

Presented by Chris Helms
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Session Learning Objectives
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Restoring a lost cache

• Hardware/Software fault recovery
• Archival Units
• Archival Unit Configuration

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Restoring a lost primary node

• Preparing for Configuration Node Recovery
• Recovering the Title Database
• Recovering the Keystore
• Reconfiguring the Nodes in the Network

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Restoring data from the cache

• Viewing Cached Content
• Using your LOCKSS node as a cache proxy
• Proxy configuration options
• Cached AU retrieval and proxy testing

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Restoring a Lost Cache

• By design, LOCKSS stores harvested material in a
  cache directory. LOCKSS will maintain the caches
  integrity through peer polling and voting with
  other members of your LOCKSS private network.
  Occasionally an outside occurrence such as a
  power failure, problematic hardware, or a piece
  of errant coding can corrupt a file system
  leaving the LOCKSS cache in an unusable state.

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Archival Units

• Archival Units may be likened to a run of
  journals or a web-based collection containing
  images, videos, and text. Long term access to
  these AUs is insured via LOCKSS harvesting and
  the polling of loyal peers. The concept of having
  loyal peers insures that data may be gained from
  other peer nodes if the original content is no
  longer available from the publisher.

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Archival Configuration
Adding Titles (manual)
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Title Selection
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Archival Configuration
Adding Titles (backup file)
Default cache config file BatchAuConfig
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Restoring a Lost Primary Node

• In order for LOCKSS to harvest and preserve data,
  certain configuration files must remain available
  via a primary node. These are the title database
  and public keystore. As a convenience, these
  files are stored within the conspectus database
  and are readily available from any participating
  LOCKSS node.

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Recovering the Title Database
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Recovering the Keystore
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Reconfiguring the Nodes in the Network
Creation and setup of the new web root directory
and Apache configuration files.
Modify the following line
Apache graceful restart
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Update the lockss.xml file
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Run hostconfig on all member nodes and modify the
Configuration URL
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Restart LOCKSS

• /etc/init.d/lockss stop
• /etc/init.d/lockss start

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Restoring Data From the Cache

• One of the key benefits of participating in a
  LOCKSS private network is having reliable,
  long-term access to your material. When available
  access to the original content is no longer
  available, the LOCKSS cache proxy server can be
  used to serve its harvested content. This
  harvested content may be pulled from any node
  participating in your LOCKSS private network. As
  we have seen in the previous section, harvested
  content may span archival units, key
  configuration files, and plugins.

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Viewing cached content
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Using your LOCKSS node as a cache proxy

• A LOCKSS node runs a cache proxy that will serve
  cached content if the original content is no
  longer available. If the original content is
  still available, the LOCKSS node will proxy the
  request to the original site.

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Proxy access control
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Proxy Options
Notes 1. The audit proxy serves only cached
content, and never forwards requests to the
publisher or any other sites. By configuring a
browser to proxy to this port, you can view the
content stored on the cache. All requests for
content not on the cache will return a 404 Not
Found error. 2. The ICP server responds to
queries sent to other proxies and caches to let
them know if this cache has the content they are
looking for. This is useful if you are
integrating this cache into an exiting network
structure with other proxies and cache that
support ICP.
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Proxy Info
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Excerpt from a PAC file
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Adding a PAC file to Mozilla Firefox
1. Windows Tools/Options MAC OS X
File/Preferences 2. Advanced/Network/Settings
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Questions ?