The ability to view the amount of used and free space on tape will be added to a future version of Firestreamer. Meanwhile, please use one of the following workarounds.

For a file medium, the amount of used space approximately equals to the medium's file size. The amount of free space is the difference between the medium's maximum size and the amount of used space. If you do not specify the maximum size for a medium, the absolute maximum value is used.

To determine the amount of used and free space for any medium, follow the steps below:

1. Load the medium in question into one of the tape drives (as opposed to a storage slot). Leave the other tape drives empty.
2. Open Windows Device Manager.
3. In the device tree, expand Tape Drives.
4. Right-click first Firestreamer Tape Drive.
5. Click Properties.
6. Click the Tape Media Capacity tab. If there is no such a tab, click Cancel to close the Properties window, right-click next Firestreamer Tape Drive and go to step 5.
7. Check the Maximum Capacity and Available Capacity values. The amount of used space can be calculated as the difference between the maximum and available capacities.

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When Firestreamer (or any other program) writes data to a file, Windows temporarily caches the data in memory instead of actually writing it, and indicates success to Firestreamer. Windows then copies the data from memory to the storage device, which is called delayed write. If an error occurs at this stage, it is too late to report the problem back to Firestreamer, so Windows has no choice but to display the error message.

To resolve the issue, try any of the following methods:

• Check Windows Event Log for related error messages.
• Check the surface of the destination disk for bad sectors.
• Verify that the destination network storage is functioning properly and has sufficient free space.
• If the destination drive is external, use the standard safe removal procedure to disconnect it. This will ensure that all memory-cached data is written to the medium before it is disconnected.

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Both Firestreamer and your backup software may lock the medium in your media drive during backup and restore operations. If you use optical media, allow up to several minutes for the medium to be finalized at the end of a backup. Make sure your backup software moved all media from tape drives to storage slots (you may need to cancel all current tape operations). If the problem persists, unload all media from the Firestreamer library.

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You cannot change the recording speed for optical media. Firestreamer configures your media drive to use the optimal read/write speed for the current medium. However, you may experience problems with writing to the low-quality optical media that may be marked with a higher recording speed than it can sustain.

Note that compressed and/or encrypted backups take longer to complete.

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The compression ratio depends on the type of data you are backing up. If the data is already compressed (for example, .docx, .zip, .cab, .jpg and .mp3 files) or is not compressible (for example, encrypted files), Firestreamer will not be able to compress it any further. As an indication, the compression ratio of 1.4-1.5 is pretty good.

Firestreamer uses a data compression algorithm similar to the one of NTFS. To estimate the compression ratio for a particular file, follow the steps below:

1. Copy the file to an NTFS volume.
2. Right-click the file in Windows Explorer, and then click Properties.
3. On the General tab, click Advanced.
4. Select Compress contents to save disk space, click OK, and then click Apply.
5. The ratio of Size to Size on disk is the approximate compression ratio that can be achieved with Firestreamer.

Note that for the results of the above test to be valid, the original file size must be 100 kilobytes or more, because Size on disk cannot be less than the cluster size of the NTFS volume (usually, 4 kilobytes).

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We tested Firestreamer on a clean machine, and the performance was similar to that of direct file copying to the destination medium. Note that Firestreamer cannot transfer data any faster than the backup software and the storage medium will provide or consume it. In addition, any third-party software that interferes, for example, an antivirus, will adversely affect the performance.

To get an indication of what you can expect from Firestreamer, copy a single file from your computer to the destination medium via Windows Explorer and measure the transfer speed. The size of the test file must be close to the size of your backup. Note that copying a group of smaller files, as opposed to a single large file, will not produce a valid result.

To improve the performance, you may want to try the following:

• Limit the maximum size of your file media, for example, to several gigabytes, to overcome the inability of some file systems (especially network ones) to efficiently handle large files.
• Disable data compression and encryption in your backup software and in Firestreamer.
• If you use an external disk drive, use Windows Disk Management to optimize the drive for performance as opposed to quick removal.
• If you use file media, defragment the destination file system.

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Data compression and encryption need a substantial amount of CPU time. In addition, any third-party software that interferes, for example, an antivirus, will adversely affect the performance. Disable compression and encryption in your backup software and in Firestreamer, and retry the operation to see if the issue is resolved.

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The abnormal behavior may be caused by a fault in any of the following components on your computer:

• A device driver.
• Hardware. For example, a storage controller or RAM.
• System software. For example, an antivirus.

To find the cause of the issue, you may want to try the following methods:

• Set up a clean machine with your backup software and Firestreamer, and verify that the issue does not occur. Begin installing your usual software and hardware components one by one, performing the backup test at each step until the issue occurs. The component which was installed last is most likely the culprit.
• If the issue occurs with a file medium on an external device (for example, a USB external HDD in file media mode, or a network share), retry the operation with a file medium on a local drive. If the test succeeds, then the problem is in the external device and its storage stack.
• If the issue occurs with an external drive medium (for example, a USB external HDD in drive media mode), connect a second IDE, SATA or SCSI internal hard disk to your computer, and retry the operation using the newly connected disk as a drive medium. If the test succeeds, then the problem is in the external device and its storage stack.
• If your machine crashes, enable the kernel memory dump and analyze it with Microsoft Debugging Tools for Windows. The name of the offending device driver usually appears in the call stack produced by the !analyze -v command.
• Enable Windows Driver Verifier against the device drivers on your machine. Verify only a few drivers at a time. Begin with non-Microsoft unsigned drivers. Do not use the Low resources simulation option because it will prevent your system from functioning. Note that Driver Verifier usually stops the machine when a faulty driver is detected. If the name of the offending driver is not displayed, you need to analyze the kernel memory dump produced by Driver Verifier.
• If during a lengthy tape operation your machine gradually slows down, misbehaves and possibly eventually crashes or locks up, then it is most likely caused by a program or a device driver leaking memory. For example, see KB968675. To troubleshoot the issue, you may want to use the Poolmon utility. For more information, see KB177415.
• If your machine becomes unresponsive, you need to manually crash it and analyze the kernel memory dump. For more information, see KB244139 and KB927069.

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