X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=docs%2Ftopten.txt;h=e69de29bb2d1d6434b8b29ae775ad8c2e48c5391;hb=d92f70685083588e2a7ce6bc312a735f6937b5a6;hp=86714944452a34fc706c1e5f6c8111e5f66bd59d;hpb=6c1f39091444e58c33362f0cc086375d9d273e77;p=debian%2Famanda diff --git a/docs/topten.txt b/docs/topten.txt index 8671494..e69de29 100644 --- a/docs/topten.txt +++ b/docs/topten.txt @@ -1,431 +0,0 @@ - -Chapter 20. Collection of the top ten Amanda questions. And answers. -Prev Part IV. Various Information Next - -------------------------------------------------------------------------------- - -Chapter 20. Collection of the top ten Amanda questions. And answers. - - -Stefan G. Weichinger - -Original text; Conversion to Docbook/XML -AMANDA Core Team - -Table of Contents - - - Reason_for_starting_this_list. - - the_DLE-question - - the_localhost-question - - the_friday-tape-question - - the_multiple-dumps-question - - the_mailing-list-question - - the_distro-question - - the_index-question - - the_tapetype-questions - - the_size-question - - the_GUI-question - - the_holding-disk_question - - ... - - - Reason for starting this list. - -Jon LaBadie once wrote to me: -" I think a good "what is Amanda", "how is it different", "can I use it in my -setup", "why is it so different" kinda document is needed to stop the constant -"how do I put 10 dumps on one tape", or "how do I make Amanda do full backups -on saturday and incrementals ..." queries off the list :)) " -Stefan G. Weichinger - - the DLE-question - -A posting from the amanda-users mailing-list (mailto://amanda-users@amanda.org) -asked: -"What, please, is a "DLE"? May it mean: Down Loadable Entity ??? Stupid. Do -Less Errors ??? Stupid again. Hmmmm ..." -People consulting the amanda-users-mailinglist for the first time often get -confused by the use of the abbreviation DLE. -It has become very common for regular mailinglist-participants to use the -abbreviation DLE, which means in its long form -DiskList Entry -A DLE refers to one entry in the disklist of an Amanda-configuration. General -usage was to describe them as partitions, or file systems. But in fact they do -not have to be either. They can be directory trees, or multiple trees, or trees -with some branches cut off. So the more generic term DLE was coined. - - the localhost-question - -People get something like: - - >Amanda Backup Client Hosts Check - >-------------------------------- - >ERROR: localhost: [access as amanda not allowed from - >amanda@localhost.localdomain] amandahostsauth failed - -and ask "Why?" -SHORT ANSWER: -DO NOT USE "localhost" as host entry in your disklist entries (aka DLEs). Use -the FQDN (Fully Qualified Domain Name) instead. -In Amanda-releases newer than 2004-03-22 there is a WARNING issued when you use -something like "localhost" or localhost.localdomain.net in your disklist. -Example (applies to Linux, syntax may be different on other systems): - - $ hostname --fqdn - oops1.oops.co.at - - $ cat disklist - oops1.oops.co.at /root root-tar # do it like this - localhost /root root-tar # DON'T DO IT LIKE THIS - -GOOD ANSWER (provided by John R. Jackson): -There are (at least) two things going on here and they should have their own -question/answer. -Completely independent of the "localhost" vs. FQDN issue are the people who get -this message because of any number of problems. Let me reword the error and -then give some typical goofs: - - ERROR: some.amanda.client: access as amanda not allowed from - amanda@some.amanda.server - amandahostsauth failed - -(error message reformatted here ...) -The first thing to understand is how to read this message. When it says "access -as amanda ..." it is telling you the client side ( amandad) is running as user -"amanda". The "... from amanda@some.amanda.server" part tells you the server -trying to connect is "some.amanda.server" and the Amanda command (e.g. amcheck -or amdump) is running as user "amanda". -The user names are typically the same on both client and server, but some -situations use different names and it is important to understand which is -which. For instance, amrecover connects as root ("... from -root@some.amanda.server") regardless of what the usual Amanda user is. -Potential problems: - -* "some.server" is not spelled exactly that way in ~amanda/.amandahosts. A - typical error is to not use a fully qualified name (although simple typos - happen as well). For instance, this line: - - - some amanda - -does not match "some.amanda.server" even though both names may be equivalent. -When Amanda looks up the host name in .amandahosts, it uses the exact name it -lists in the message. It does not try to look up abbreviations. -The only exception to this is that the lookup is case insensitive. - -* The user name listed in ~amanda/.amandahosts is not the one trying to connect - from the server. In particular, watch out for the "root" case listed above - for amrecover. The Amanda server typically needs lines like this in its - .amandahosts file: - - - some.amanda.client root - - -* There are permission problems on the client preventing user "amanda" from - reading its own .amandahosts file. Make sure the file itself is readable to - the user "amanda" and all the parent directories down to it can be traversed. - A simple test is: - - - su - amanda -c "cat ~amanda/.amandahosts" - -Now, back to the localhost issue. This: -Do NOT USE "localhost" as host entry in your disklist entries (aka DLEs). Use -the FQDN (Fully Qualified Domain Name) instead. -is not really an answer, more of a command :-). -There are a couple of reasons to NOT use "localhost". First is amrecover will -not work as expected. When it connects to the server (even though they are the -same machine), the server will look for the matching DLE's using the real host -name, not "localhost". The sethost command inside amrecover can "fix" this, but -why not just set it up right in the first place? -Another reason to not use "localhost" is because it helps with future changes. -As the Amanda configuration grows, it's not at all unusual to take a server and -make it a client of a new, larger, server. But now "localhost" does not point -to the same machine it used to. If the FQDN of the machine had been used all -along, this upgrade would have been much easier. -There is also no performance reason (any more) to use "localhost" instead of -the FQDN. Modern OS network stacks know to shortstop packets destined for the -local machine and never let them hit the wire. Yes, I'm old enough to remember -when they didn't :-). - - the friday-tape-question - -"How do I make Amanda do full backups on Saturday and incrementals ... ?" -"My backup screwed up on tuesday and now it keeps asking for the tuesday tape -even though it is wednesday!" -ANSWER: -The short answer is: You can't. -The longer answer is: You can. But you should not. -The reason: Amanda is designed to schedule your backups. Let "her" do it. -When you want to make the best use of Amanda, you have to let go the classic -schedule where one used to have one tape dedicated to each day of the week, and -one for the friday. -The main difference in concept is this: -In the classic backup scheme you said: -"I want to have incremental backups from Mo-Th and a full backup on Fr." -Using Amanda you say: -"I want to have at least one full backup in 5 days." -So you don't have to specify exactly WHEN the full backup should happen. You -just tell Amanda some goals it should reach and let it work out the details. -There are several advantages in this: -Imagine that you have your classic backup-schedule running fine. Everything is -calculated and designed well, so your tape gets filled well each night. -Now one user generates an unforeseen huge amount of data. For example, he -duplicates one big data-directory by mistake. -So the size of the directory raises within one day, maybe for multiple GBs. -Would your classic backup-scheme catch that? Or would it run out of tape, -simply because it was not calculated to have that filesystem with that size? -Amanda would try to catch it (and most of the time succeed ...). -As there is the estimate-phase before actually dumping something, Amanda can -look at the DLEs and determine the actual size at the time. It also determines -the size of an incremental backup so it can test for the Plan B to just run a -level-1 if it does not work out to do a level-0 for that DLE. -If the size of the DLE is much bigger than it has been the run before, Amanda -still tries to meet your goals. It just reschedules stuff, combining full and -incremental backups to meet the goals as good as possible. -So you can think of it as some algorithm which lets Amanda adapt to your data. -If you set the goals in a reasonable way, Amanda will just do the rest. - - the multiple-dumps-question - -"How do I put 10 dumps on one tape?" -ANSWER (provided by Jon LaBadie): -Use another backup scheduler. -This question is most often asked by individual computer users as a cost -consideration. -Amanda was developed at the University of Maryland Computing Center for use in -moderately sized computer centers. That it can be used by users of small -computers is a testament to its designers and maintainers. -While it may seem cost effective to put as many dumps as possible on a single -tape, in a computing center that would be considered a very risky decision. The -loss of, or damage to, a single tape would be the loss of many days worth of -dumps. That is too much to chance. -Thus, Amanda was designed to never overwrite a non-Amanda tape, nor an Amanda -tape from a different configuration, nor an Amanda tape from the current -configuration that is still "active", i.e. has backups on the tape more recent -than the dumpcycle length. -If you still feel you want Amanda to put multiple dumps on a single tape, there -is a crude way to accomplish your goal. -But first ask yourself, "If my data is worth so little that I can not afford a -few more tapes, why am I backing it up?" - -Note - -Most of the time it won't be YOU paying for the tapes as you may be working for -some company. If your boss tries to force you into doing this multiple-dumps- -on-one-tape thing, be sure to point him at this risk. Business people tend to -understand the price-difference between some tapes and a major data-loss. -Stefan G. Weichinger -A common way to put multiple dumps on a single tape is to let them accumulate -on the holding disk and use the amflush command when you want to put them on -tape. I.e. if you want a weeks' worth of backups on a single tape, leave the -tape out for a week. Then stick it in and run amflush. -(Better make sure you have sufficient disk space on your holding disk.) -Note, a slight variant of this is to have the parameter autoflush in -amanda.conf set to "yes". (Users of older Amanda-releases should check out if -their version already supports that parameter.) -Then after several dumps have collected in the holding disk, put the tape in -before that day's amdump is scheduled. amdump will both flush the holding disk -to tape and add the regularly scheduled dump. - - the mailing-list-question - -"How do i get off this damn mailing list?" -ANSWER: -Frequent users of the Amanda-users-mailing-list get mails like containing -"unsubscribe" -as people are trying desperately to get off the list. -Everyone that subscribes to Amanda-users gets a mail in which the following is -contained: ->Welcome to the amanda-users mailing list! ->Please save this message for future reference. Thank you. ->If you ever want to remove yourself from this mailing list, >you can send mail -to with the following >command in the body of your email -message: -> unsubscribe amanda-users -Did you see that? You have to send your mail to , and NOT -to ! - - the distro-question - -"Where can i get binary distributions of Amanda?" -ANSWER: -It is well known that various distributions of Linux contain precompiled -packages of Amanda-servers and -clients. -Due to the design of the Amanda source code, in which MANY features can be -configured at compile-time, it is heavily and heartily recommended to take the -effort and roll your own special flavour. -Thinking about these things before actually doing backups with Amanda will help -you in many ways. And you get the benefits of compiling your own paths/devices/ -configurations right into your Amanda-binaries. You also get the benefit of a -much more improved understanding of the way Amanda does backups. - - the index-question - -"Why does amrecover say there are no index files?" -ANSWER: -It is very likely that Amanda is right about that. Check your dumptypes and -make sure they include the line: - - index yes - -If this is the case and you still get that message, recheck the installation of -your amindexd-binary. -Is the line in your (x)inetd-configuration pointing to the proper binary? Is -this line active (= uncommented)? Did (x)inetd reread that configuration since -that line was edited? - - the tapetype-questions - -" amtapetype has been running for 9 days, is this normal?" -"Will Amanda work with my frozboz tape drive/library?" -"Which device is my changer?" -" amtapetype is broken, it says my 200GB tape only holds 65GB." -"My file marks are HUGE, 1.3MB (on a 200GB tape, i.e. about 0.05% of the total -capacity, or expressed another way, maybe 2 mm of a 125000 mm tape ...)" -ANSWER: -It is crucial to tell Amanda the truth about the tape-device(s) you want to -use. Given the wrong values, Amanda can't calculate proper dumpsizes, free -tape-space or make valuable use of compression. -Before you consider running amtapetype, think twice. Twice. -As tapedrives tend to be produced by not-so-small companies and as those not- -so-small companies tend to produce more than one unit to maximize profits, it -is very likely that someone else has the same device you have or at least one -that uses the same technology. -Many people have already run amtapetype to determine the proper values to fill -in their amanda.conf-files. Browse the example amanda.conf in your Amanda- -tarball for various tapetypes. Browse the Amanda-FAQ on http://www.amanda.org. -Chances are high that you find just your device described. -As in every other topic discussed in internet mailing lists, please try finding -an answer there before asking on the Amanda-users list. -If your device is so exotic that even the Amanda-users can't help you, you -still have your copy of amtapetype. -Before you start running it, note this: - -* DISABLE hardware compression on your drive. - -A common mistake is to have hw-compression enabled. amtapetype uses random data -to test for the size and speed of your drive. Random data is pretty bad at -getting compressed. In fact it gets even bigger so the results given back are -useless. Disable it even if you are planning to use your drive with enabled hw- -compression. - -* Expect it running long. - -As you can read in the man page, amtapetype writes the full tape twice, which -can be a lot of data for modern drives (approaching a TByte). It also writes -tape marks every 10 MBytes (by default) which forces the drive to flush its -internal buffers and slows the process down. You can shorten this by giving -amtapetype a better estimate of the expected capacity: -$ amtapetype -e 100g -f /dev/nst0 -This "prepares" amtapetype to expect a tape with 100 GB capacity. -If amtapetype really runs for 9 days, you can be pretty sure there is something -wrong with your approach. -And for the filemark-size: Just read the question again. - - the size-question - -"How do I back up a partition that won't fit on a tape?" -aka -"Can Amanda span one file over multiple tapes?" -ANSWER: -There are two basic rules when it comes to these things: - -* Amanda supports using more than one tape in a single run of amdump -* Amanda does not support splitting a dump image across tapes - -The first rule lets you make use of two or more tapes for a single amdump when -using a tapechanger-robot or a tape-library. You could even use multiple tapes -with the chg-manual-script, waiting patiently for one tape to be filled, then -change tapes manually. -No matter how many tapes you can put in your robot or how long you can stay -awake to change tapes you can NOT split the backup image of one of your -disklist entries (aka DLEs) across multiple tapes. No way. -So you may ask the first question listed above. As the size of harddisk- drives -grows steadily it is not uncommon to have multiple hundreds of gigabytes of -harddrive capacity in one system. Compared to the size of your maybe not-so- -shiny-anymore tapedrive this seems (and maybe is) huge. -What to do? -Don't split your dump image (it can't be done), split your DLEs. -You have to use GNU-tar in your dumptypes for this. -Try to redefine your disklist as in the following example: - - fatboy /bigmama_BIGDIR /bigmama { # a big subdirectory - comp-user-tar - include "./bigdir" - } - fatboy /bigmama_FILES01 /bigmama { # all files beginning with... - nocomp-user-tar - include "./file[01]*" - } - fatboy /bigmama_FILES23 /bigmama { - nocomp-user-tar - include "./file[23]*" - } - ... - fatboy /bigmama_REST /bigmama { # Catch-all - nocomp-user-tar - exclude "./file[0-9]*" - exclude append "./bigdir" - } - -(example taken from a mail by Paul Bijnens on the Amanda-users-list) -The trick is to form several chunks of data of which each fits on tape. In the -example above the chunks are formed by regular expressions matching files named -like file00, file123 and file9999. You have to look at your DLEs to find the -patterns describing your chunks. -As this technique forms data-chunks that fit on your tape it also helps Amanda -to schedule your backups more flexible. Having more and smaller DLEs, the -planner has more variations to possibly schedule your backups, so this will -help getting nice output from amadmin balance, too. - -Note - -DLE-spanning might be supported by Amanda in a future release. - - the GUI-question - -"Is anyone working on a GUI for Amanda?" -ANSWER: -Actually there are people working on GUIs for Amanda. Aside from that the -question really is: "Does anyone need a GUI for Amanda?" -Given the fact that backups tend to be run at night while people tend to sleep, -who would need a fancy GUI showing 3D-backup-diagrams via X11? The only part of -backups where GUIs maybe could add some comfort is recovery for unexperienced -users. - - the holding-disk question - -"Why does it say "Some dumps may have been left in the holding disk." and there -is nothing in the holding disk?" -ANSWER: -The third word in the message. Some dumps MAY have been left. - - ... - -Please feel free to suggest additions and corrections. Write to the amanda- -users-mailinglist at mailto://amanda-users@amanda.org. - -Note - -Refer to http://www.amanda.org/docs/topten.html for the current version of this -document. -------------------------------------------------------------------------------- - -Prev Up Next -Chapter 19. Amanda FAQ Home Chapter 21. Amanda WISHLIST -