Recently, there was a post on this list about loss of data with VXA drives if the
power is cycled while a tape is in the drive. Some of the statements in that post were
incorrect. One very important correction: VXA tape drives DO have the capability to
recover data after a power loss. This is an explanation from the Ecrix technical
support team of exactly how this works.
HOW DO MOST DRIVES HANDLE POWER LOSS?
With most tape backup devices, a loss of power means a loss of data. If power is lost
during a write operation a tape drive will not have a proper end of data marker which
defines where the current backup finished. This separates new and old data. When the
'power loss' tape is read a fatal error may occur when a tape drive crosses the
boundary between new and old data.
HOW DOES VXA HANDLE POWER LOSS?
If a VXA drive is powered off in the middle of a write operation, it can still recover
the data. It does this by correcting the data format to take into account the absence
of an end of data marker. This will allow reading of the tape up to the point where
power was lost. However, the drive must go through a recovery process to determine
where the boundary between new and old data. You can
expect 1-4 hours before the drive comes ready. With firmware of V2848 or lower the
middle (rectangle) LED would blink. With V2959 firmware the right arrow will blink
green/yellow indicating a format recovery is underway.
HOW DOES VXA HANDLE OTHER INTERRUPTIONS?
If a write operation stops sending data to the tape drive for 10 minutes the drive
will write a 'pseudo' end of data marker and then reposition itself to the back side
of the last block of data that was just written. This way the tape can be read with
no problems.
A WORD OF CAUTION
All this being said, it is NOT a good idea to power off ANY tape drive with a tape
still in the drive. The best protection for your data is to remove the tape before
powering off your drive.
If you are having difficulties with any tapes caused by a power interruption, please
contact us at [EMAIL PROTECTED]
- Frank Saab
[EMAIL PROTECTED]
Ecrix
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