Course12:Basic - Flash Memory Drives

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This book describes the usage of CF cards with innovaphone gateways.

Contents

Concept

The Flash Memory drives enables the innovaphone gateway to work as a WebDAV server. You can use the CF card to store files/data and access them via HTTP. The drives can be mounted to your local filesystem, so that all standard functions for manipulating files and folders (copy, delete, paste etc.) can be used. The single limitation of the innovaphone WebDAV implementation is the inability to handle file attributes (e.g. write protected, hidden).

To make it short, by using the drives you can save the cost for running an additional WebDAV server.

Some examples for the use of a WebDAV server are:
  • customized announcements
  • voicemail
  • update server
  • logging server
  • fax server

Types


/DRIVE/CF0

Older gateways (e.g. IP810), used a Compact Flash card as drive. Although CF cards have some benefits (e.g. they are user installable without opening the device), they are not state-of-the-art any more. Newer gateways (e.g. IP811) therefore use installable SSD drives instead of the CF-card.

Both the CF card and the SSD are accessible as http://x.x.x.x/DRIVE/CF0.

Technical fish-help.png information on recommended manufacturers and card types, can be found in our wiki.

/DRIVE/FLASH

Also, newer gateways like the IP811 feature a secondary drive which is known as Flash Disk. This memory is built-in. It has different size, depending on the gateway model. You will find the size in the Hardware section of our data sheets (e.g. fish-help.png IP811 Features).

The Flash Disk is accessible as http://x.x.x.x/DRIVE/FLASH.


Accessing the WebDAVserver

Accessing the CF-card

To check and access the content of the CF card a web browser can be used. Also it is possible to perform some basic operations like mounting/unmounting or formatting the card. The process of mounting/unmounting the drive memory is important when removing it from the device. By unmountig it first, you prevent damage of stored data. (note that the flash disk is built-in and cannot be removed).

If advanced file handling operations are needed, you must use a WebDAV client. The WebDAV client enables you to add/create, copy, delete, rename and move files and directories on the drive.

You can use a stand-alone client, such as WinSCP which you can download from the Recommended Tools and Firmware for this Course page.

However, it may be more convenient to use Microsoft's WebDAV client, that is built-in to the operating system. This allows you to work with files on the CF card just like with any other file on a local or network drive by letting you access the directories with an UNC path such as \\172.31.31.1\DRIVE\CF0. This will work from within just any program, not only the windows explorer.

Unfortunately, depending on various Windows settings, this may or may not work well. This is why we work with WinSCP in this course.

A Linux operating system usually offers davfs or davfs2 to mount a WebDAV drive.

Configuring WinSCP
Is easy smile
You screenshot.png create a New Site and hit Login.

  • The File protocol must be WebDAV
  • The Port number is the port you configured as Port for HTTP in fish-help.png Services/HTTP/Server (usually 80)
  • The Host name is simply the device's IP address
  • The User name is the device's admin User Name as configured in fish-help.png General/Admin

Enable HTTP access of the drive contents

WebDAV is built on top of HTTP(/HTTPS, so access to the drive will happen through the device's HTTP Server. This is configured in fish-help.png Services/HTTP.

On the device that has the drive (and this runs its WebDAV server), public access to the drive may be configured within the section Public compact flash access (beware: this is obviously misleading for newer devices which do not have a CF card, so the heading may change in the future). For example, you can configure /DRIVE/CF0/ as Path and tick the Read and/or Write check-marks in Services / HTTP / Server to allow full authenticated access to the CF/SSD drive. Access to paths where no public access is granted must be authenticated using the box's admin user and password.

When a device needs to access a remote WebDAV server (e.g. if a PBX Waiting Queue object needs to access an announcement which is stored on a separate device's drive), the access credential can be configured in the HTTP client configuration Services / HTTP / Client. You would then configure all remote URLs (e.g. http://172.31.31.2/DRIVE/CF0/announcement/) along with their access user and password within the Authenticated URLs list. Note that you must specify the exact URL used, see fish-help.png Services/HTTP/Client for details.

Backup & Syncronisation

Backup

The flash memory drives are used for storing data. This can contain items like e.g. voicemails or recorded conversations, which are usually regarded as sensitive data and must therefore be backed up.

As we have seen, these file can be accessed just like any other network resource. This allows users to perform backups using standard tools such as NTBackup on Windows or tar/cpio on unix-ish platforms.

One limitation of a WebDAV server however is that it does not manage file attributes such as the archive attribute. The result for our backup concept is that we cannot use incremental backup methods but must always do a full backup of the CF card content.

The file system used on the drives is FAT32. This enables an administrator to perform disaster recovery by accessing the damaged card on a CF card reader at his local PC. Depending of the used operating system various repair tools can be used to recover the damaged data.

Note that Flash Disk, SSD and CF-Card content is not restored during fish-help.png Maintenance/Upload/Config nor is it saved with fish-help.png Maintenance/Download/Config! During an upload, the drive content is not touched.

Synchronisation

In redundancy scenarios using a standby PBX, you will want to have the WebDAV server content available in case that the first PBX is defect.

There are solutions for this problem:

  • Use an external WebDAV server.

    Do not use the local drive to store information that must be available in the redundancy case. Use an external WebDAV server and point your master as well as the slave/standby PBX to it. In case that the master is down, the WebDAV server is still working and handles request coming from the standby PBX.

  • Synchronize the content of all drives

    Again an external server is needed, running something like an synchronization service. On Windows you could use for example wikipedia.ico Robocopy to check and compare the content of all drives periodically. It will then copy new or modified files from the master drive to the slave drive.

Reset to Factory Defaults

During reset to factory defaults, the flash memory drive types are treated differently.

The removable CF-Card and SSD drives (/DRIVE/CF0) are not touched using factory reset. All data remains intact.

However, the built-in flash disk (/DRIVE/FLASH), is considered integral part of the device (as it is not removable) and is therefore cleared during reset to factory defaults. All data is lost and you need to reformat and mount the device. It is essential to backup any sensitive data from the flash disk before the reset to factory defaults!

Usage scenarios

Announcements



The simplest way to use a drive is for deploying custom announcements. These announcements can then be used by the innovaphone PBX for Waiting Queues or as Music on Hold source.
To avoid format conversion or encoding during a call, the announcements have to be present as coder - specific raw sound stream data files (i.e. G.711, G.722, G.7239 or OPUS-NB/WB format).

The conversion of source files coded in wav, mp3, flac or ogg formats into the codec-specific formats can easily be done via our link_intern.png audio converter freely accessible at our homepage.

Uploading a source file will automatically download a zipped file including all conversions.

Voicemail



The next common scenario for drive usage is in combination with the PBX Voicemail object. It stores both the sound-files and XML-scripts for the voice mail application as well as the the recorded messages. This brings up the questions on the disk space requirements needed for a voice mail message. As a rule of thumb you can assume that a G.711 message of 1 minute uses approximately 480 kBytes. Depending on the consumer behaviour, you can estimate the average length of one message in order to calculate the maximum amount of messages that fits on your drive.

Example: average length of message left is 1.5 minutes. Your PBX has 1000 voice mail users. Your drive has 16000 MB available space. You can record 40 messages per user.

Logging



When using the drive for logging all information created by the syslog interface of the innovaphone gateway will be saved on the card. A log directory will be created automatically. You can fish-help.png configure the maximum size of the log files as well as the storage time of the log files.

Update Server



Another common scenario for using a drive is as an update server. You can execute update-scripts from the local WebDAV server and also store your configuration and firmware files.

Linux



You can run our fish-help.png Linux Application Platform (a.k.a. LAP) on the SSD (or CF-card for older devices). This gives you a platform to run applications such as
  • Fax Server
  • Reporting
  • Exchange Calendar Connector

The LAP is not covered in the basic course. It can not run on the Flash Disk (/DRIVE/FLASH).

Summary

The flash memory drives are an easy to implement solution for configuring additional functions like voice mail and logging for the innovaphone PBX. It is an alternative to using 3rd party WebDAV server.
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