NAS Appliance

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NAS Appliance

Latest version: 4.0.2-1

NAS Appliance


At a Glance
Catalog	System
Category	Misc. Appliances
User volumes	yes
Min. memory	96 MB
OS	Linux
Constraints	no
Questions/Comments	Ask Forum

Functional Overview

The NAS appliance is a shared file storage appliance. It provides file storage accessible over HTTP, NFS, and CIFS file protocols.

The NAS appliance serves files contained within a configured (pluggable) data volume thus providing the ability for the content served by the appliance to be changed easily as well as the ability for the volume to have varied sizes. For example, if NAS is being used to store log files, the data volume does not need to be as large as what may be needed to store content for an Apache server.

The root directory of the volume is shared and the HTTP, NFS, and CIFS (samba) servers see the same volume, at the same root. The NFS server exposes the volume as a shared named /mnt/data. The CIFS server exposes the volume as a share named share. The root directory of the volume is accessible for read-only access by the HTTP server and for read/write access by the NFS and CIFS (samba) server.

The security for HTTP access may be open (no user/pwd), fixed single user/pwd (from property) or from .htpasswd file stored within the root directory of the data volume.

The CIFS access is anonymous. It is assumed that only appliances that are allowed to access the volume are connected to the cifs terminal. This eliminates the need to configure complex security settings on the client and server and makes it possible to simply connect appliances that need file access to the cifs input.

There are three key use cases for the NAS appliance:

Serving large files over HTTP. The cifs interface is used to add/remove files (usually exported over a separate gateway)
As a shared file server through which other appliances/servers exchange files (fully internal to the application)
As a log server through which other appliances/servers store their log files so that those logs may be easily accessed/viewed by an administrator rather than having to log into each individual appliance.

Boundary

Resources

Resource	Minimum	Maximum	Default
CPU	0.1	16	0.2
Memory	96 MB	32 GB	256 MB
Bandwidth	1 Mbps	2 Gbps	250 Mbps

Terminals

Name	Dir	Protocol	Description
http	in	HTTP	Terminal on which HTTP requests are received. This terminal is used to access NAS's data volume using the HTTP/1.1 protocol. HTTP requests are served by HTTP server version 2.2.3-31.
nfs	in	NFS	Terminal on which NFS requests are received. This terminal is used to access NAS's data volume using the NFS/3.0 protocol.
cifs	in	CIFS	Terminal on which CIFS requests are received. This terminal is used to access NAS's data volume using the CIFS/1.0 protocol. CIFS requests are served by Samba server version 3.0.28-1.
mon	out	CCE	Sends performance and resource usage statistics. This terminal may be left unconnected if it is not used.

The default interface is enabled. This provides the ability for administrators to log into the appliance using the '3t ssh comp' command to perform maintenance or to troubleshoot problems. One possible maintenance activity might be to add/remove users from the .htpasswd file stored on the data volume.

User Volumes

Volume	Description
data	Read/write volume providing storage for the files to be served by the appliance

The following file may reside within the root directory on the volume:

File	Description
.htpasswd	HTTP Password File. If present, this file is inaccessible from the http interface but will be accessible through the cifs interface (so that new users can be added/passwords changed)

Properties

Property name	Type	Description
http_url_prefix	String	Root path (URL) at which the web server should expose the file system. Default: /
http_dir_enabled	String	Enable/disable displaying of directory listing when a directory does not contain an index.html file (yes or no). Default: no
http_sec_mode	String	HTTP security mode (none, single, or htpasswd). Default: none
http_sec_realm	String	HTTP security realm in case http_sec_mode is single or htpasswd. Default: Restricted Area
http_user	String	User name for HTTP access in case http_sec_mode is single. Default: (empty)
http_pwd	String	Password for HTTP access in case http_sec_mode is single. This property may be left empty (no password) in the case when http_user is set to a valid user. Default: (empty)
cifs_read_only	String	Restrict CIFS access to read-only (yes or no). Default: no
cifs_case_sensitive	String	Enable/disable case sensitive file paths (yes or no). Default: no
nfs_read_only	String	Restrict NFS access to read-only (yes or no). Default: no
log_dir	String	Directory beginning from the root directory of the data volume where the HTTP and samba server log files are to be stored. For example, if this property is set to /, the log files will be stored within the root directory of the data volume. If this property is empty then no logs are written to. Default: /
timezone	String	Specifies the time zone used in the appliance. If this property is empty, the timezone is not modified and left as-is. A list of supported time zones is available here? . Default: empty

Error Messages

The following messages may appear in either the appliance log file or the system log of the grid controller when the appliance fails to start:

failed to mount data volume
failed to set permissions on the data share
Samba failed to start
NFS failed to start
Apache failed to start

Typical Usage

Static Content Server

The following diagram shows a typical usage of NAS for a simple web server application:

typical usage of NAS for a simple web server application

Appliances in use:

web - input gateway, class IN
maint - input gateway, class IN
urlsw - URL switch, class URLSW
admin - Linux Server, class LINUX
nas - NAS appliance, class NAS
apache - Apache server, class APACHE

The nas appliance in this example is used to serve the static content of the web site (for example, images) as it is simple to configure and less resource-demanding, while a separate apache server is set up to serve the dynamic content (for example, forms interface, and so on)

The admin appliance in this example is used to authenticate users and provide access to the cifs terminal of the nas appliance so that an administrator may update the set of files exposed by nas through its http terminal.

Note: The urlsw appliance in this example is not shipped with CA 3Tera AppLogic, but can be built using Apache and pound. The Apache appliance in this example is not shipped with CA 3Tera AppLogic. However, CA 3Tera AppLogic does provide a similar appliance named WEB5.

HTTP Access:

web accepts HTTP requests coming to the application and passes them to urlsw through its out terminal. urlsw sends HTTP file requests for dynamic content through its out1 terminal to be served by nas1 on its http terminal. urlsw forwards all other HTTP requests through its aux terminal to be served by Apache.

CIFS Access:

When an administrator needs to modify the set of files made available for HTTP access by nas, the administrator connects and logs into the admin appliance through the maint appliance. The user then mounts the CIFS share exposed by nas (if it is not already mounted) and modifies the files as needed.

Example:

Property name	Value	Notes
data	mydata	Data volume holding the files to be served by the web server
http_url_prefix	/images	Root path at which the web server should expose the file system.
http_dir_enabled	no	Directory listing is disabled.
http_sec_mode	none	No security is enabled for HTTP access.
cifs_read_only	no	The CIFS share is exposed for read/write access.
cifs_case_sensitive	yes	Enable case sensitive file paths.

Shared Storage

The following diagram shows a typical usage of NAS as shared storage for multiple application servers.

typical usage of NAS as shared storage for multiple application servers

Appliances in use:

app1 - Application server, class APP
app2 - Application server, class APP
nas1 - NAS appliance, class NAS

The nas1 appliance in this example is used as shared storage for app1 and app2. Both application servers have read/write access to the directories and files served by nas1.

app1 and app2 issue CIFS requests through their out terminals to the cifs terminal of nas1 to access files stored on the volume shared by nas1. Any changes made by one application server are seen by the other application server.

Example:

Property name	Value	Notes
data	mydata	Data volume holding the files to be shared between the applications
cifs_read_only	no	The CIFS share is exposed for read/write access.
cifs_case_sensitive	yes	Enable case sensitive file paths.

Log Server

The following diagram shows a typical usage of NAS as a log server.

typical usage of NAS as a log server

Appliances in use:

user - Input gateway, class IN
admin - Input gateway, class IN
webs - Load Balancer, class HALB
srv1 - Web server, class WEB5
srv2 - Web server, class WEB5
dbase - Database server, class MYSQL5
logs - NAS appliance, class NAS
mail - Output gateway, class NET

The logs appliance in this example is used to store the log files for the two web servers and the database server and makes those files available through its http terminal.

The log terminals for the web servers (web1 and web2) and the database server (dbase) are all connected to the cifs terminal of logs so that when they write to their log files, the files are stored on the logdata volume that is configured on logs.

When an administrator needs to inspect the log files, he connects via the admin gateway to the http terminal of the logs appliance. He logs in with the configured administrator user name and password and is shown a listing of the root directory of the logdata volume from which the administrator is free to view the log files he is interested in.

Example:

Property name	Value	Notes
data	logdata	Data volume holding the log files
http_url_prefix	/logs	URL root path where log files can be accessed.
http_dir_enabled	yes	Directory listing is enabled.
http_sec_mode	single	HTTP security mode is single user.
http_user	admin	User name for HTTP access.
http_pwd	admin123	User password for HTTP access.
cifs_read_only	yes	The CIFS share is exposed for read-only access.
cifs_case_sensitive	yes	Enable case sensitive file paths.

Additional Configuration Information

Change the Size of the Data Volume Used by NAS

The features of the http and samba servers are limited and only those features that properties support are exported.

To change the size of the data volume used by NAS

Stop the application if it is running.
Using the editor or 3tvol utility, create a volume within the application with the desired size.
If you want to keep the files that are on the existing volume, mount both volumes, copy the files from the old volume to the new volume and unmount both volumes.
Using the editor, update the data volume for the NAS appliance to be the newly created volume.
Using the editor, destroy the old volume and save the application.

Start the application.

Open Source and Third Party Software Used on the Appliance

NAS uses the following 3rd party open source packages in addition to the 3rd party open source packages used by its base class LUX5.

Software	Version	Modified	License	Notes
apr	1.2.7-11	No	Apache 2.0	N/A
apr-util	1.2.7-11	No	Apache 2.0	N/A
cups-libs	1.3.7-18	No	GPLv2	N/A
curl	7.15.5-9	No	MIT	N/A
gnutls	1.4.1-3	No	LGPLv2.1	N/A
httpd	2.2.3-43	NO	Apache 2.0	N/A
libgcrypt	1.4.4-5	No	LGPLv2.1	N/A
libgpg-error	1.4-2	No	LGPLv2.1	N/A
libidn	0.6.5-1.1	No	LGPLv2.1	N/A
libjpeg	6b-37	No	Distributable	N/A
libpng	1.2.10-7.1	No	zlib	N/A
libsmbclient	3.0.33-3.29	No	GPLv2	N/A
libtiff	3.8.2-7	No	MIT	N/A
mailcap	2.1.23-1	No	ISC	N/A
perl-Convert-ASN1	0.20-1.1	No	Artistic	N/A
postgresql-libs	8.1.22-1	No	BSD	N/A
quota	3.13-1.2.5	No	BSD	N/A
samba	3.0.33-3.29	No	GPLv2	N/A
samba-client	3.0.33-3.29	No	GPLv2	N/A
samba-common	3.0.33-3.29	No	GPLv2	N/A