LTO / LTFS option
When using TeraCopy for restoring files from a LTO tape, formatted as LTFS, you're running into occasional timeout errors. With having a LTO option I hope one could avoid timeout errors ...
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I to am trying to use Terra Copy with LTFS tape backup. I had an issue, when writiting to tape using 3.3.Beta, that the file copy from disk to tape LTFS timed out. Teracopy showed on the log, and when checking the tape it was missing. LTFS assings the tape drive as a drive letter, but it needs a constant stream of data to copy. The tape drive iteself pauses to write the directory information out occasionaly must write the directory.. The tape drive will always get the data there until full, so the timeout for larger files needs to be extended. (so the tape drive can pause and reposition itself if needed.) THere should be an "LTFS option for the job such that the timeout setting is ignored. When reading from tape, it should not sort the files, but just copy in the natural tape order in a single threaded read > multithreaded write to disk... On copy to Tape, it should work the other way.. Multip copy multi threaded read to > Single threaded write. (With a large memory buffer..) My lto7 drive can stream data at 300mbs per second, but the drives deliver slower.. To optomize tape backup times the data read from disk should gointo as big a memory chunk as possible and then stream that big chunk to tape. The larger amount of memory it can use to then write quickly to tape... In my testing, LTFS works great with big files., slows downs with many small files and many directories..
I'm writing to you today because I've been using your software for file transfers with my HP ULTRIUM TAPE UNIT (LTO-5) and I have found it to work decently with LTFS tape drives, as long as asynchronous file transfer is disabled.
However, the only issue I've encountered is that the software begins pre-reading files when they are selected, causing unnecessary movement of the tape. This can be improved by simply not reading or writing anything until the "job" is initiated.
This would result in better functionality with Ultrium tape drives that use the LTFS filesystem.
It's worth noting that the LTFS filesystem is completely transparent and works well.
The only thing it requires is that unnecessary read and write accesses be avoided and that
any I/O operation is done in sequential mode and not parallel.
I would appreciate it if you could take this feedback into consideration for future updates.
Thank you for your attention to this matter.
Best regards,
We are using TeraCopy for backing up ONTO LTO LTFS formatted tapes. Even the creation of the hash codes on verify runs fairly fast using TeraCopy. We see the transfer speed go up to 145 MByte/s.
However, TeraCopy turns out to be almost useless the other way around. When copying BACK from LTO LTFS formatted tape towards our local RAID/SSD storage, we get like 8 MByte/s, so less than 10%. Copying the very same file using standart Explorer copy function runs about 130 to 140 MByte/s again, but it will not run verification with hash codes.
Is there any option in TeraCopy which we might be trying to get this sorted out?
LTO LTFS and TeraCopy would be an insane combination if working always as smoothly as during backup operation.
I can help providing kind of "beta test" for new versions to deal with the tape restore correctly.
From other software vendors we found that the LTO LTFS appears to emulate a RAM disk device (Broken X Disk Manager, which we us to catalog our LTFS tapes including zip and 7z archives - making backup hell fast by storing big 7z files rather than thousands small files).
So if you take my offer to volounteer here, just contact me.
Cheers
Axel Mertes