Binary01 Posted June 4, 2012 Report Share Posted June 4, 2012 I setup Retrospect 9 to backup a directory that is 2.5 TB in size to a tape auto loader with seven 780 GB tapes. The backup script is currently paused with the error "Needs Media". When I click on "choose media" it's looking for tape 8. I should have over 5 TB of space with these seven tapes. When I check the media set for this script it shows 3.1 TB of free space. Why is it asking for another tape and not completing the backup? How do I complete this backup? Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted June 4, 2012 Report Share Posted June 4, 2012 Is this something that has worked fine before and now stopped working? Or is this a completely new setup? If the data is fed too slow to the tape drive, blank blocks are written to the tape while the tape drive waits for data. How is the 2.5TB "directory" connected to the backup server? How is the tape drive/loader connected to the backup server? How many files are there in the 2.5/B "directory"? Many small files backs up much slower than a few large files. Any other bottlenecks you might think of? Such as overloaded backup server? Running the Retrospect server on a PowerPC Mac? Anything? Are the clamied 780GB per tape the native capacity? Or does is assume the seldom obtained 2:1 compression? Retrospect uses a tape until: 1) The tape is full. If there are many blank blocks the tape fills quicker. 2) There are unrecoverable write errors, in which case you find details in the log file. So it seems as Retrospect really needs another tape. Quote Link to comment Share on other sites More sharing options...
ggirao Posted June 4, 2012 Report Share Posted June 4, 2012 I usually have the same issue, I use LTO4 Tapes but they never passes 1TB. Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted June 4, 2012 Report Share Posted June 4, 2012 I usually have the same issue, I use LTO4 Tapes but they never passes 1TB. LTO4 tapes have a native capacipty of 800GB, so 1TB isn't bad at all.It isn't many types of files that can be compressed 2:1. Most of todays files are already compressed and can't be compressed further: JPG, MP3, PDF, audio and video files and so on. 1 Quote Link to comment Share on other sites More sharing options...
ggirao Posted June 4, 2012 Report Share Posted June 4, 2012 LTO4 tapes have a native capacipty of 800GB, so 1TB isn't bad at all. It isn't many types of files that can be compressed 2:1. Most of todays files are already compressed and can't be compressed further: JPG, MP3, PDF, audio and video files and so on. You're right! Quote Link to comment Share on other sites More sharing options...
Binary01 Posted June 4, 2012 Author Report Share Posted June 4, 2012 Is this something that has worked fine before and now stopped working? Or is this a completely new setup? If the data is fed too slow to the tape drive, blank blocks are written to the tape while the tape drive waits for data. How is the 2.5TB "directory" connected to the backup server? How is the tape drive/loader connected to the backup server? How many files are there in the 2.5/B "directory"? Many small files backs up much slower than a few large files. Any other bottlenecks you might think of? Such as overloaded backup server? Running the Retrospect server on a PowerPC Mac? Anything? Are the clamied 780GB per tape the native capacity? Or does is assume the seldom obtained 2:1 compression? Retrospect uses a tape until: 1) The tape is full. If there are many blank blocks the tape fills quicker. 2) There are unrecoverable write errors, in which case you find details in the log file. So it seems as Retrospect really needs another tape. I just setup Retrospect 9 to replace Retrospect 6 for my tape backups. When I created the media set it told me it will erase all data and create a new set. The data was copying at 1.7 GB/s so I dont think that's the problem I don't think the server was bottlenecked at all as I let the backup run over the weekend when nobody is using it. The tapes are 780 GB and I am not usign any compression. The media set still shows 3.1 TB of free space so I can't believe it needs another tape. Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted June 4, 2012 Report Share Posted June 4, 2012 The data was copying at 1.7 GB/s so I dont think that's the problem Perhaps you mean 1.7GB/minute? The tapes are 780 GB and I am not usign any compression. What kind of tapes are they?Why did you turn off compression? Perhaps you mean you didn't use software compression? The hardware compression in the tape drive is still on, right? I can't believe it needs another tape. Well, that is what Retrospect tells you, right?If you check the properties of the members of the media set, how much is stored on each tape? The media set still shows 3.1 TB of free space Sometimes the "free space" is way off.Does it say how much is stored and how much is left to store (of the 2.5TB)? Just put in another tape or two and see what happens. OK? Quote Link to comment Share on other sites More sharing options...
Binary01 Posted June 4, 2012 Author Report Share Posted June 4, 2012 What kind of tapes are they? Why did you turn off compression? Perhaps you mean you didn't use software compression? The hardware compression in the tape drive is still on, right? I didnt use software compression. How can I tell if hardware compression is on? Well, that is what Retrospect tells you, right? If you check the properties of the members of the media set, how much is stored on each tape? Sometimes the "free space" is way off. Does it say how much is stored and how much is left to store (of the 2.5TB)? Just put in another tape or two and see what happens. OK? From the screenshot above it looks like I should have plenty of space to continue backing up. Should I perhaps change the media action from "No Media Action" to one of the other choices? Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted June 5, 2012 Report Share Posted June 5, 2012 I didnt use software compression. How can I tell if hardware compression is on? It is usually a real pain to turn off hardware compression, using a utility provided by the tape driva manufacturer. So unless you did that, the hardware compression is on. From the screenshot above it looks like I should have plenty of space to continue backing up. I say the screenshot tells you about a display bug in Retrospect. It assumes that each and every tape always holds 781.1GB of data. Never more, never less. This is, of course, far from the truth. For instance, see my post above about the (lack of) compressability of different types of files. What is of interest here are tapes 3 and 7, as they seems to hold much less data than the rest of the tapes. Have you gotten any warnings or errors in the log? You forgot to answer two important questions: What kind of tapes are they? Does Retrospect tell you how much is stored and how much is left to store (of the 2.5TB)? I also have two new questions: How many files are there in the 2.5TB backup? What kind of files are they? (In terms of how well they can be compressed). Media action? Well you could try a "recycle" backup, but I don't think it would help. You would probably get the same result the next time. Quote Link to comment Share on other sites More sharing options...
Binary01 Posted June 6, 2012 Author Report Share Posted June 6, 2012 It is usually a real pain to turn off hardware compression, using a utility provided by the tape driva manufacturer. So unless you did that, the hardware compression is on. I say the screenshot tells you about a display bug in Retrospect. It assumes that each and every tape always holds 781.1GB of data. Never more, never less. This is, of course, far from the truth. For instance, see my post above about the (lack of) compressability of different types of files. What is of interest here are tapes 3 and 7, as they seems to hold much less data than the rest of the tapes. Have you gotten any warnings or errors in the log? I dont really see anything in the logs. How can I view a detailed log? You forgot to answer two important questions: What kind of tapes are they? Does Retrospect tell you how much is stored and how much is left to store (of the 2.5TB)? The tapes are Sony LTX400G LTO 3 Tape Ultrium 3 400/800 GB Retrospect states that it backed up 2.2 TB and has 329.8 GB left. I also have two new questions: How many files are there in the 2.5TB backup? What kind of files are they? (In terms of how well they can be compressed). There are around 150,000 files. The files are mostly Illustrator/Photoshop files and JPEG images. Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted June 6, 2012 Report Share Posted June 6, 2012 Right, the native capacity is 400GB per tape. Images doesn't compress well, which means you can NOT assume 2:1 compression. In fact, images can't normally be compressed more than they are on disk. See above for possible reasons for blank blocks on the tapes, which means you won't reach the native capacity. But at least you are close. You need more tapes. (Hopefully only one.) End of story. Quote Link to comment Share on other sites More sharing options...
twickland Posted June 6, 2012 Report Share Posted June 6, 2012 Retrospect states that it backed up 2.2 TB and has 329.8 GB left. As an addendum to Lennart's comments, remember that the capacity of a tape, unlike a hard drive volume, cannot be predicted accurately but can only be estimated. (Retrospect uses a rather generous estimate.) Whenever a tape member is full or can no longer be written to because of an error, you need a new tape member, no matter what Retrospect's estimate says. That being said, there are a lot of variables with tape and tape drives. Because most of our backups are from remote clients direct to tape, I was not surprised to find that we were able to write only about 500 GB to our 400/800 GB LTO-3 tapes, as this was about the same ratio we'd been getting with DAT. However, after we switched from this LTO-3 SCSI drive to a new LTO-5 SAS drive, we've been achieving a much-more-respectable 1.4 to 1.5 TB per 800/1600 LTO-4 tape. Quote Link to comment Share on other sites More sharing options...
Lennart_T Posted June 7, 2012 Report Share Posted June 7, 2012 I was not surprised to find that we were able to write only about 500 MB to our 400/800 MB LTO-3 tapes, Sorry for being a nitpicker, but that should be GB, not MB. We use LTO-3 tapes with Retrospect 7.6 for Windows. We normally get 500-550GB per tape. We use a new (or erased) set of tapes every week and sometimes we get as low as 380GB on some tapes, for no apparent reason. It is mainly the same files as last week. (We run disk-to-disk-to-tape.) Quote Link to comment Share on other sites More sharing options...
twickland Posted June 7, 2012 Report Share Posted June 7, 2012 Sorry for being a nitpicker, but that should be GB, not MB. I guess that's what can happen when reflecting too much on the old days of DAT. Quote Link to comment Share on other sites More sharing options...
Binary01 Posted June 7, 2012 Author Report Share Posted June 7, 2012 Right, the native capacity is 400GB per tape. Images doesn't compress well, which means you can NOT assume 2:1 compression. In fact, images can't normally be compressed more than they are on disk. See above for possible reasons for blank blocks on the tapes, which means you won't reach the native capacity. But at least you are close. You need more tapes. (Hopefully only one.) End of story. Thanks for helping me understand my issue. I purchased another tape and hopefully my backup can complete successfuly Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.