Retrospect in Mac OS on OS X
Has anyone gotten Retrospect to see the MacOS running in OS X? When the test the IP address from the Retrospect server, it 'sees' the machine. However, when I try to connect to it directly for backups, it does not see it. Is there a workaround? ___ Forbes Benning Web Application Developer CoreSolutions Development Inc. FileMaker Solutions Alliance Associate Web Site: http://www.coresolutions.on.ca/ London: (519) 641-7727 - Toronto: (416) 410-8649 ___ -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050.
tape capacity
Hello, I'm new to this list and subscribed because I have a question I hope one of you will be able to answer for me. I'm using Retrospect 4.2 for Mac, backing up a total of three Mac Servers to an APS DAT drive. The tapes I use are Sony DDS3 125P which state a Native (I'm not sure what Native means) capacity of 12.0 GB. After looking at the log of how much data is being backed up, it added up to 14.3 GB. How can this be? It seems that the tape shouldn't be able to handle it but I receive no errors. Any explanations? Suggestions? thank you, -matt -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050.
Re: tape capacity
One word: Compression. Native capacities are with no compression. For example, your 12GB drive can hold up to 12GB of un-compressed data. Normal hardware compression can get up to 2:1 compression, giving a total maximum of 24GB. Reality check, I've been getting about 27GB onto a 20GB/40GB drive. This is typical. You should be able to get 17-18GB on the drive on average. Warning, my rant follows: What I don't get is that they have not improved the compression on tape drives all that much. I mean, compression programs regularly get 4:1 to 24:1 compression depending on the data. Heck, a JPEG image is typically 12:1 compression. Yes, I do know that a compressed file usually cannot be compressed any further. Throw a JPEG file into a ZIP or Stuffit program and you might gain 1% at best. However, the majority of files on a computer are not compressed. I once took a System Folder that was 220MB in size and compressed it using Stuffit down to 28MB. That's almost 8:1 compression. Yes, the process to some time to do, but maybe it should be an option. I'd like to get another 10GB out of this tape drive as there are weeks when the tape runs out on Thursday night needing just another 1-2 MB to finish the week. I stopped backing up my laptop on the regular backups just to make room. I really hate added more tapes to a set. I only backup 11 machines on this. If I had a choice of 4:1 compression, and could expect a yield of little better than 2:1, everything would fit and I could add another machine to the backup. Hello, I'm new to this list and subscribed because I have a question I hope one of you will be able to answer for me. I'm using Retrospect 4.2 for Mac, backing up a total of three Mac Servers to an APS DAT drive. The tapes I use are Sony DDS3 125P which state a Native (I'm not sure what Native means) capacity of 12.0 GB. After looking at the log of how much data is being backed up, it added up to 14.3 GB. How can this be? It seems that the tape shouldn't be able to handle it but I receive no errors. Any explanations? Suggestions? thank you, -matt -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050. -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050.
Re: tape capacity
One word Matt: Compression Native capacity is the amount of uncompressed data that will fit on the tape. The drive has a hardware-based compressor that squeezes the data as it streams from the SCSI port to the write mechanism. The amount the data gets compressed depends upon the characteristics of the data being processed, but slightly less than 2:1 is normal. The amount of data being reported on the tape is the amount of uncompressed data. I use a similar mechanism and usually get a little over 20Gig to a 125m tape. As always, your mileage may vary :) Hope this helps Hello, I'm new to this list and subscribed because I have a question I hope one of you will be able to answer for me. I'm using Retrospect 4.2 for Mac, backing up a total of three Mac Servers to an APS DAT drive. The tapes I use are Sony DDS3 125P which state a Native (I'm not sure what Native means) capacity of 12.0 GB. After looking at the log of how much data is being backed up, it added up to 14.3 GB. How can this be? It seems that the tape shouldn't be able to handle it but I receive no errors. Any explanations? Suggestions? thank you, -matt -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050. ___ Philip Chonacky, IS Manager Barrett Companies ph. (617) 577-9500 fx. (617) 577-1010 mailto:[EMAIL PROTECTED] -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050.
RE: tape capacity
"Native" is the actual amount of data that the tape can theoretically store, before compression. A 12.0 Gig file should fit on a 12.0 Gig capacity tape. Suppose you are able to take a 16.0 Gig file and compress it down (using PKZIP or whatever) to 12.0 Gigs. Now that 16.0 Gig file can fit on the 12.0 Gig tape. Usually, the tape drive has built-in compression. In this case, the tape drive may receive 16 Gigs of data from the server during a backup, but the tape drive compresses the data just before it writes it to tape. The compressed data uses less tape space, and more data can fit on the tape. Often, you'll see tape drive and tape media capacities quoted as double their native capacities. They are assuming that the data being written to tape is well-compressible (after compression the data is 1/2 its original size). In the instance of DDS3, it often is stated that it is a 24 Gig drive, when in fact, it is a 12 Gig drive with a potential of storing up to 24 Gigs after the data is compressed (assuming a 2:1 compression ratio). Hope this helps. Brad. -Original Message- From: matt holland [mailto:[EMAIL PROTECTED]] Sent: Friday, October 20, 2000 1:30 PM To: [EMAIL PROTECTED] Subject: tape capacity Hello, I'm new to this list and subscribed because I have a question I hope one of you will be able to answer for me. I'm using Retrospect 4.2 for Mac, backing up a total of three Mac Servers to an APS DAT drive. The tapes I use are Sony DDS3 125P which state a Native (I'm not sure what Native means) capacity of 12.0 GB. After looking at the log of how much data is being backed up, it added up to 14.3 GB. How can this be? It seems that the tape shouldn't be able to handle it but I receive no errors. Any explanations? Suggestions? thank you, -matt -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050. -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050.
Retro Mac And VXA Drive
Could we get an update from Dantz and Ecrix on the VXA/Retro Mac issue, as reported by MacIntouch, 10-20-00 (see below)? The post on MacIntouch goes a long way to explaining some of the problems I've been seeing with my VXA drive. If not for having just finishing rebuilding my LAN and upgrading my net connection, and installing new servers, routers and switches, I was going to dive into troubleshooting the problems I've been having. Maybe all I have to do is wait for the firmware update? I've not only got many 206's, but errors 102 (trouble communicating), 203 (hardware failure), error 205 (lost access to storage medium), error 100 (device rejected command). In addition, after these errors, the drive will not continue to use the current tape, and always wants a new one (whether 4 gigs or 40 gigs were written to it)--leading me to believe the the end of write markers were never properly written, which could leave the tape in an unusable condition. Also, the drive can take up to several hours to eject a tape after one of these errors--following Ecrix's advice to eject a tape: power down the drive, disconnect it from the backup Mac server, turn it on and hit the eject button many times quickly in a row. Makes for a very tedious process of continually regenerating backup sets. I've been using a BW G3/300 with a Miles Initio Blue Note scsi card and OS 9.0.4 with Retro 4.3. Using the VXA tool to maximize capacity over speed seemed to exacerbate the situation. Thanks, Jim Coefield [EMAIL PROTECTED] From MacIntouch: "Just got off the phone with Ecrix tech support. I had just set up my new VXA-1, and was getting a lot of type 206 (bad media) errors from Retrospect. "According to Kelly at Ecrix, this results from what is apparently a timing issue between Mac Retrospect and the Ecrix drive, and is not necessarily a media problem. Kelly says that Dantz and Ecrix have tracked the problem down, and Ecrix expects to release a firmware update to solve the problem within the next week or so." -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050.
Re: tape capacity
Ok, explain to me...I took a 220MB system file and compressed it down to 28MB. Obviously this is lossless as I can recover individual files from within it that are things like extensions, fonts, etc. I admit, JPEG, MPEG, etc. are lossful, but modems have been doing v.42bis compression which is 4:1 on the fly for a long time now. Granted, the speed is only 53k at best (although some faster network equipment also uses a subset of v.42bis), so the time frame from receiving to sending would be larger that you would get with receiving to sending to local device like a tape drive. I'm wondering if it would be possible for Retrospect to do some software compression that may be slower, but would allow greater inline compression. I would guess that the software compression built into Retrospect is the same algorythem that hardware compression drives use. By getting with a company like Alladin Systems, it would seem like they could improve on that technology. If Dantz did something like this, obviously having a choice of Hardware compression or software compression would still be there, but adding to the software compression may be 3 levels. Normal, Better (slower), Best (slowest). The speed of the compression would depend heavily on the speed of the CPU doing the backups. So if I had my Dual 1Ghz Processor Alpha box running NT doing backups, the best compression would be barely noticeable performance hit. I do think that if Dantz should at least talk to someone at Alladin about it. 8?) One (compound) word: Lossless The compression methods that you are lusting after introduce errors (artifacts) into the resulting decompressed data. This may be acceptable for sound, photos and video but to totally unacceptable for storage of system files, programs and most other data. -- -- To subscribe:[EMAIL PROTECTED] To unsubscribe: [EMAIL PROTECTED] Archives:http://list.working-dogs.com/lists/retro-talk/ For urgent issues, please contact Dantz technical support directly at [EMAIL PROTECTED] or 925.253.3050.
