File Media
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Overview
The file medium is an ordinary file on any file system that is accessible to the Firestreamer kernel mode drivers. The actual location of file media has no meaning to Firestreamer. It does not matter whether you have your file media in the same folder, different folders or even on different volumes. You can freely move file media to different locations, provided that you update the initial media layout.
Firestreamer does not automatically create file media. You should create file media as needed either by using the Create File Media form or from a custom script. Alternatively (not recommended), you can create a zero length file by any method, and then use it as a new file medium.
You can store file media on the file systems that support built-in data compression or encryption (for example, NTFS compressed or encrypted volumes). However, you should only use file system compression when the file media content is neither encrypted nor compressed. In most cases, encrypted or already compressed data is not compressible any further.
You can burn a file medium to an optical medium (for example, a Blu-ray disc) as an ISO image, and then use the optical medium as a Firestreamer drive medium.
Medium Name
In the initial media layout, the name of a file medium is the full path to the file, for example, D:\Folder\MyTape_0001.fsrm or \\Server\Share\MyTape_0002.fsrm. The drive, server, share and directory names are not interpreted by Firestreamer. The file name extension has no special meaning either, but we recommend that you use .fsrm. The file name is used as the medium's bar code, and therefore must follow the bar code naming rules, with the exception that lowercase letters are allowed. While you can freely change the file location, do not rename the file itself because it will change the bar code.
If necessary, you can access a file medium on a local file system by using the volume name instead of a drive letter, for example, \??\Volume{95f09245-ea34-11dc-b18f-806e6f6e6963}\Folder\MyTape_0001.fsrm. This helps to avoid the dependency on drive letters (which may change), and allows access to the file systems that have no drive letters assigned to them. To replace drive letters with volume names in a media layout, use the Substitute Drive Letters command of the Media Layout Editor. You can view some of the volume names in the Properties text boxes in the Add Drive Media form.
Network-Based File Media
If your file media is located on a network file system, note the following:
- You need to configure the security context (see below) that will be used to open the file media.
- Do not use a mapped drive letter in the medium name, because the drive letter may be either unavailable or assigned to a different resource in the security context used to open the file. Use the full UNC path instead (for example, \\Server\Share\MyTape_0002.fsrm).
- If you use the software that dynamically creates a drive letter (for example, a VPN solution), make sure that the drive letter is accessible in kernel mode under the security context used to open the file media.
Security Context
Firestreamer opens file media in the security context of the Firestreamer Helper Service. By default, the service runs under the Local System account that may not have access to your file media. If this is the case, you need to configure the service for it to log on to the account that has such access.
For example, you logged on as Administrator and mapped a drive as N:. If the Firestreamer Helper Service is running under a different account, then N: under that account may point to some other drive, or may be invalid at all. Even if N: points to the correct drive, the service's account may not have the appropriate permissions to access the files on the drive. To resolve the issue, you may want, for example, to associate a login script with the service's account to have the destination storage prepared when the service starts up. Alternatively, you can schedule a task that runs under the same account as the Firestreamer Helper Service, prepares the destination storage and then starts the backup.
Maximum Size
The initial media layout can specify the maximum size of a file medium. If the maximum size is not provided, then it defaults to the absolute maximum value of 8 terabytes. Setting the maximum size has no effect on the current size of a medium. If the free space on the file system is exhausted before the maximum size is reached, the current backup will fail. When the data on tape is overwritten, the file medium automatically reduces in size.
If you specify the maximum size for your file media, then ideally the total maximum size of your tapes should be less than the amount of free space on the file system. We recommend that you do not allow your file media to grow in size beyond a certain reasonable value, for example, by setting the maximum medium size in the media layout, or by changing media frequently. This reduces the risk of losing all your data if a single file medium is corrupted, improves the maintainability of individual files, and allows to overcome the inability of some file systems (especially network ones) to efficiently handle large files.
As a guideline, the maximum size of a file medium should not exceed 50-100 GB for a local file system and 5-20 GB for a network one.
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