|
|
| (30 intermediate revisions by 8 users not shown) |
| Line 1: |
Line 1: |
| Stefan G. Weichinger, November - December, 2003 ; minor updates in April, 2005.
| | See {{man|7|amanda-devices}}. |
| ==Introduction==
| |
| | |
| Since release 2.4.3 Amanda supports the usage of a output driver called "file". See the manual page of amanda, section [[Amanda#OUTPUT_DRIVERS|OUTPUT DRIVERS]], for more information.
| |
| | |
| As the name suggests, this driver uses files on disk as virtual tapes.
| |
| Amanda can write to and read from virtual tapes, just like real tapes.
| |
| A bunch of virtual tapes can even be manipulated with a changer.
| |
| | |
| Possible Uses
| |
| * Test installations: You can easily explore the rich features of Amanda on systems without tape drives. Virtual tapes are usually also much faster than many real tape drives.
| |
| | |
| * Inexpensive installations: Without buying a tape drive you can enjoy the benefits of Amanda and backup to a bunch of harddisks. You can create CD/DVD-sized backups which you can burn onto optical disks later. Or you can backup to external disks connected with Firewire or USB.
| |
| | |
| * disk-based installations: You can use the file driver to backup onto a set of virtual tapes hosted on a bunch of hard-disks or a RAID-system. Combined with another Amanda configuration that dumps the virtual tapes to real tapes, you can provide reliable backup with faster tapeless recovery. This is called "disk-to-disk-to-tape" backup by some people today.
| |
| | |
| Please be sure to understand the differences between holding disks and virtual tapes. The two serve different purposes; holding disks allow for parallelism of multiple disklist entries (DLE's) being backed up while virtual tapes are a replacement for physical tapes.
| |
| | |
| The virtual tapes are also called "vtapes" in this document.
| |
| | |
| ==Simple virtual tapes==
| |
| | |
| A virtual tape is implemented as a directory with a subdirectory named "data" in it:
| |
| | |
| $ mkdir -p /space/vtapes/tape1/data
| |
| | |
| This tape can be manipulated by the [[ammt]] command, a replacement for the system command "mt". The
| |
| ammt command understands the different output drivers from Amanda:
| |
| | |
| $ ammt -f file:/space/vtapes/tape1 status
| |
| $ ammt -f file:/space/vtapes/tape1 rewind
| |
| | |
| Vtapes are always non-rewinding. Just like Amanda needs them. That's why you always need to rewind it when you want to start reading a vtape from the beginning.
| |
| | |
| Basic writing to a vtape can be done with [[amdd]], a replacement for the system command "dd".
| |
| Virtual tapes have no real builtin capacity; the upper limit is "diskspace, the final frontier". However Amanda does obey the size you specify in tapetype definition of a vtape in amanda.conf. The
| |
| amdd command also can specify an upperlimit on the virtual tapesize with the '''-l''' option:
| |
| | |
| $ amdd -l 200k if=/dev/urandom of=file:/space/vtapes/tape1 bs=32k
| |
| amdd: write error: No space left on device
| |
| 8+0 in
| |
| 6+1 out
| |
| | |
| The above command writes 200 Kbytes of garbage (6 full blocks of 32k + 1 partial block) on the vtape before it bumps into the end of the virtual tape.
| |
| | |
| When there is no "data" subdirectory in a vtape, the vtape is "offline".
| |
| You could burn the contents of the data directory to a CD-R, and store that away.
| |
| When you want to read it, just mount is as a "data" directory, or even simpler, create a symlink "data" pointing to the mounted cdrom.
| |
| | |
| $ rm -r /space/vtapes/tape1/data
| |
| $ ammt -f file:/space/vtapes/tape1 status
| |
| file:/space/vtapes/tape1: status: OFFLINE
| |
| $ ln -s /media/cdrom /space/vtapes/tape1/data
| |
| $ ammt -f file:/space/vtapes/tape1 status
| |
| file:/space/vtapes/tape1: status: ONLINE
| |
| | |
| Amanda cannot write a to cdrom, but can use it as a read protected vtape. (But ''you'' can write a cdrom from the contents of the data directory with another program.)
| |
| | |
| We can use such a vtape as a tape device in amanda.conf with a line like:
| |
|
| |
| tapedev file:/space/vtapes/tape1
| |
| | |
| And then point the data subdirectory each day to a different place.
| |
| | |
| ==Virtual tapes with chg-multi==
| |
| | |
| Amanda can use many virtual tapes, and operate the bunch of vtapes by a virtual tape changer.
| |
| | |
| Create 5 vtapes:
| |
| | |
| for i in 1 2 3 4 5; do mkdir -p /space/vtapes/tape$i/data; done
| |
| | |
| Now we a server with 5 tape drives. They are virtual tapes, but Amanda isn't picky about that.
| |
| | |
| The "chg-multi" changer uses many tapes drives to emulate a tape changer. Vtapes can also be used here.
| |
| Change amanda.conf for the "test" configuration to have these values:
| |
| | |
| tpchanger "chg-multi"
| |
| changerfile "chg-multi.conf"
| |
| # tapedev may be commented out and is ignored if present
| |
| | |
| And add a file in the same directory as amanda.conf with the name we specified above as the changerfile '''chg-multi.conf''':
| |
| | |
| multieject 0
| |
| needeject 0
| |
| gravity 0
| |
| ejectdelay 0
| |
| statefile /home/amanda/test/changerstatus
| |
| firstslot 1
| |
| lastslot 5
| |
| slot 1 file:/space/vtapes/tape1
| |
| slot 2 file:/space/vtapes/tape2
| |
| slot 3 file:/space/vtapes/tape3
| |
| slot 4 file:/space/vtapes/tape4
| |
| slot 5 file:/space/vtapes/tape5
| |
| | |
| Run "amcheck test" to verify we did not make an error somewhere,
| |
| and we label the tapes in all the slots:
| |
| | |
| $ for i in 1 2 3 4 5; do amlabel test TEST-$i slot $i; done
| |
| ...
| |
| $ amtape test show
| |
| $ amtape test reset
| |
| | |
| And we are ready to use our tape changer with 5 tape drives.
| |
| | |
| ==Setup==
| |
| | |
| This guide assumes you have setup the basic Amanda services as described in Amanda Installation Notes.
| |
| | |
| The configuration in this HOWTO is called "daily".
| |
| | |
| Before beginning you will need to decide on dedicated parts of your hard disks for your virtual tape storage. While this space could be spread among several file systems and hard disks, I recommend to dedicate at least a specific partition, better a specific physical harddisk to the task of keeping your vtapes. The use of a dedicated disk will speed things up definitely.
| |
| | |
| The disk space you dedicate for your vtapes should NOT be backed up by Amanda. Also, for performance reasons there should be NO holding disks on the same partition as the vtapes, preferably not even on the same physical drive.
| |
| | |
| If you only have one harddisk, it will work out, too, but you will suffer low performance due to massive head-moving in your harddisk, resulting from copying data between the filesystems.
| |
| | |
| * Prepare the filesystem used for the vtapes. Decide on where to put your files, create the appropriate partition(s) and
| |
| filesystem(s) and mount them. In our example we have the dedicated partition hdc1, mounted on /amandatapes for vtape storage.
| |
| | |
| $ mount
| |
| [...]
| |
| /dev/hdc1 on /amandatapes type reiserfs (rw)
| |
| [...]
| |
|
| |
| Make sure there is space left. Determine the amount of space you will use.
| |
| | |
| $ df -h /amandatapes
| |
| Filesystem Size Used Avail Use% Mounted on
| |
| /dev/hdc1 20G 0G 20G 0% /amandatapes
| |
| | |
| In our example we have 20GB diskspace left on /amandatapes.
| |
| | |
| * Determine length and number of tapes. After deciding on the number of vtapes you want to create, evenly allocate the
| |
| available space among them.
| |
| | |
| Look at the following rule of thumb: As many filesystems exhibit dramatically reduced performance when they are nearly full I have chosen to allocate only 90% of the available space. So we have:
| |
| | |
| (Available Space * 0.9) >= tapelength * tapecycle
| |
| | |
| This is a very conservative approach to make sure you don´t suffer any performance drop due to a nearly-full-filesystem. As it is
| |
| uncommon for AMANDA to fill, or almost fill an entire tape you may also wish to use more space than that. So you could determine
| |
| possible combinations of tapelength/tapecycle with the more general formula:
| |
| | |
| Available Space >= tapelength * tapecycle
| |
| | |
| In our example we take the conservative approach:
| |
| :* 20 GB * 0.9 = 18 GB to use
| |
| and so we could create the following combinations:
| |
| :* 18 GB = 18 GB * 1
| |
| :* 18 GB = 9 GB * 2
| |
| :* 18 GB = 6 GB * 3
| |
| :* 18 GB = 3 GB * 6
| |
| :* 18 GB = ......... you get the picture.
| |
| | |
| Using only one tape is generally considered a bad idea when it comes to backup, so we should use at least 3 tapes (for testing purposes), better 6 or more tapes.
| |
| :* 18 GB = 3 GB * 6
| |
| so we get the value 3 GB for the tapelength if we want to use 6 tapes.
| |
| | |
| * Create a tapetype definition. Add a new tapetype definition similar to the following to your amanda.conf. I named my definition "HARD-DISK". Choose whatever name you consider appropriate.
| |
| | |
| define tapetype HARD-DISK {
| |
| comment "Dump onto hard disk"
| |
| length 3072 mbytes # specified in mbytes to get the exact size of 3GB
| |
| }
| |
|
| |
| You don´t have to specify the parameter speed (as it is commonly listed in tapetype definitions and reported by the program amtapetype). AMANDA does not use this parameter right now.
| |
| | |
| There is also an optional parameter filemark, which indicates the amount of space "wasted" after each tape-listitem. Leave it blank and AMANDA uses the default of 1KB.
| |
| | |
| * Think about tapechangers.
| |
| | |
| As you will use a set of vtapes, you have to also use a kind of vtape-changer. There are several tape-changer-scripts included in the AMANDA. Read more about tape-changer-scripts in AMANDA Tape Changer Support. Right now there are two scripts that can be used with vtapes. These scripts take different approaches to the handling of tapes.
| |
| :*The script chg-multi handles many drives with a tape in each drive.
| |
| :*The script chg-disk handles a library with one drive and multiple tapes.
| |
| | |
| So with vtapes you could look at it this way: chg-multi simulates multiple tape drives with one tape in each drive. chg-disk simulates one tape-library with multiple tapes in. As chg-multi exists for a much longer time than chg-disk, it is still used in many AMANDA-vtape-installations.
| |
| | |
| Contrary to chg-multi, which is a generic changer-script that must be somewhat adjusted to the use of the file-driver, chg-disk offers exactly the behavior needed for handling vtapes. IMHO the approach is much more logical, so I recommend to use chg-disk in new AMANDA-vtape-installations.
| |
|
| |
| To use chg-disk you need to have at least amanda-2.4.4p1-20031202.
| |
| | |
| Choose the one that fits your way of vtape-handling and -maintenance. In this HOWTO I only cover the use of chg-disk. Usage of
| |
| chg-multi is pretty similar and will maybe covered in a later version of this document.
| |
| | |
| * Set up your tape-config. In the general section of amanda.conf, you have to set the parameters tapecycle , tapetype , tpchanger , changerfile , tapedev , rawtapedev and changerdev.
| |
| | |
| $ vi /usr/local/etc/amanda/daily/amanda.conf
| |
| ...
| |
| | |
| tapecycle 6
| |
| tapetype HARD-DISK
| |
| tpchanger "chg-disk"
| |
| changerfile "/usr/local/etc/amanda/daily/changer"
| |
| tapedev "file:/amandatapes/daily"
| |
|
| |
| This reflects the use of your defined tapetype. The parameter tapecycle tells AMANDA how much tapes can be used, Set this value according to the number of tapes you want to use. The parameter tapetype , points to the tapetype definition you have created before. The parameter tpchanger tells AMANDA to use the generic tape-changer-script to handle the vtapes. You can think of it as a virtual tape-changer-device.
| |
| | |
| The parameter changerfile is used to give chg-disk the "prefix" for the "%s-changer, %s-clean, %s-slot" files it needs. Use something like "changer" in your config-dir. Please note that this file does NOT have to exist, but it won't hurt anyway. The parameter tapedev tells the chg-disk-script where the root-dir for your vtapes is.
| |
| | |
| In our example the vtape-files go to /amandatapes. To separate multiple configurations, we decided to use subdirectories according to the configuration name "daily".
| |
| The parameter changerdev is NOT needed with chg-disk as it is not parsed by chg-disk.
| |
| | |
| * Create the virtual tapes.
| |
|
| |
| Gene Heskett has committed a shell-script which creates and labels the vtapes in one step. Stefan G. Weichinger will
| |
| generalize this script and contribute it, this script will just read your settings in amanda.conf and create the
| |
| appropriate vtape-directories.
| |
| | |
| Now you have to create the tape-directories. chg-disk needs a directory structure like:
| |
| | |
| slot_root_dir -|
| |
| |- info
| |
| |- data -> slot1/
| |
| |- slot1/
| |
| |- slot2/
| |
| |- ...
| |
| |- slotn/
| |
| where 'slot_root_dir' is the tapedev 'file:xxx' parameter and 'n' is the tapecycle parameter.
| |
| | |
| So in our example we do:
| |
| $ mkdir /amandatapes/daily
| |
| for the 'slot_root_dir' and
| |
| $ mkdir /amandatapes/daily/slot1
| |
| $ mkdir /amandatapes/daily/slot2
| |
| ....
| |
| | |
| for the virtual slots that will later contain the vtapes. If you have many vtapes to create and their names follow a pattern you may be able to do them all with a single loop such as:
| |
| | |
| $ for n in 1 2 3 4 5 6 7 8 9 10 11 12
| |
| > do
| |
| > mkdir /amandatapes/daily/slot${n}
| |
| > done
| |
|
| |
| Create the info-file:
| |
| $ touch /amandatapes/daily/info
| |
| | |
| and link the first slot to the data-file (to "load" the vtape into the first slot):
| |
| $ ln -s /amandatapes/daily/slot1 /amandatapes/daily/data
| |
| | |
| Make sure the AMANDA-user has write-permissions on these directories:
| |
| $ chown -R amanda_user /amandatapes
| |
| $ chgrp -R amanda_group /amandatapes
| |
| $ chmod -R 750 /amandatapes
| |
|
| |
| * Label the virtual tapes. As the virtual tapes are handled just like physical tapes by the AMANDA-Server they have to be
| |
| labeled before use.
| |
| | |
| $ amlabel daily daily1 slot 1
| |
| ....
| |
| $ amlabel daily daily2 slot 2
| |
| ....
| |
| | |
| If you have many vtapes to label and their names follow a pattern you may be able to do them all with a single loop such as:
| |
| | |
| $ for n in 1 2 3 4 5 6 7 8 9 10 11 12
| |
| > do
| |
| > amlabel daily daily${n} slot ${n}
| |
| > done
| |
|
| |
| Label all your created tapes according to the "labelstr"-parameter in your amanda.conf. Consult the amlabel-man-page for details.
| |
| | |
| * Test your setup with amcheck. Run amcheck daily (or, more general, amcheck <config>) and look for anything AMANDA complains about.
| |
| | |
| A proper output looks like:
| |
| | |
| $ amcheck daily
| |
| Amanda Tape Server Host Check
| |
| --
| |
| Holding disk /amhold: 6924940 KB disk space available,
| |
| that's plenty
| |
| amcheck-server: slot 2: date 20031115 label daily02
| |
| (exact label match)
| |
| NOTE: skipping tape-writable test
| |
| Tape daily02 label ok
| |
| Server check took 0.377 seconds
| |
| | |
| Recheck your files if errors occur.
| |
| | |
| ==Recovery==
| |
| | |
| Recovering files from vtapes is very similar to recovering files from a "real" tapechanger. Make sure you read the chapter Restore.
| |
| I will simply paste a amrecover-session here (provided by JC Simonetti, author of chg-disk):
| |
| | |
| # /usr/local/amanda/sbin/amrecover woo
| |
| AMRECOVER Version 2.4.4p3. Contacting server on backupserver.local ...
| |
| 220 backupserver AMANDA index server (2.4.4p3) ready.
| |
| 200 Access OK
| |
| Setting restore date to today (2004-10-08)
| |
| 200 Working date set to 2004-10-08.
| |
| Scanning /BACKUP2/holding...
| |
| Scanning /BACKUP/holding...
| |
| 200 Config set to woo.
| |
| 200 Dump host set to backupserver.local.
| |
| Trying disk /tmp ...
| |
| $CWD '/tmp/RECOVER' is on disk '/tmp' mounted at '/tmp'.
| |
| 200 Disk set to /tmp.
| |
| Invalid directory - /tmp/RECOVER
| |
| amrecover> sethost backupserver.local
| |
| 200 Dump host set to backupserver.local.
| |
| amrecover> setdisk /
| |
| 200 Disk set to /.
| |
| amrecover> cd /etc
| |
| /etc
| |
| amrecover> add passwd
| |
| Added /etc/passwd
| |
| amrecover> list
| |
| TAPE B3_14 LEVEL 0 DATE 2004-09-26
| |
| /etc/passwd
| |
| amrecover> extract
| |
|
| |
| Extracting files using tape drive file:/BACKUP2/slots/ on host
| |
| backupserver.local. The following tapes are needed: B3_14
| |
|
| |
| Restoring files into directory /tmp/RECOVER
| |
| Continue [?/Y/n]? Y
| |
|
| |
| Extracting files using tape drive file:/BACKUP2/slots/ on host
| |
| backupserver.local. Load tape B3_14 now
| |
| Continue [?/Y/n/s/t]? Y
| |
| . /etc/passwd
| |
| amrecover> quit
| |
| 200 Good bye.
| |
| | |
| Nothing spectacular? The trick is this: When AMANDA asks you
| |
| | |
| Load tape B3_14 now
| |
| Continue [?/Y/n/s/t]?
| |
| | |
| you have to run the following in a second terminal:
| |
| | |
| $ amtape woo slot 14
| |
| amtape: changed to slot 14 on file:/BACKUP2/slots/
| |
| | |
| This step is necessary to load the proper tape into your virtual changer. Let me express this in a more general way:
| |
| | |
| When amrecover prompts for the tape it needs to restore the files you requested, you have to "load" the tape it requests. The recommended way to do this is to use amtape. The options that make sense in this context are:
| |
| | |
| # amtape
| |
| Usage: amtape <conf> <command>
| |
| Valid commands are:
| |
| [...]
| |
| slot <slot #> load tape from slot <slot #>
| |
| [...]
| |
| label <label> find and load labeled tape
| |
| [...]
| |
|
| |
| If you know which slot contains the requested tape (for example, if you have tape daily01 in slot 1, tape daily02 in slot 2, and so on) you may use the first option. If you just know the label of the tape you need, use the second option.
| |
| | |
| To continue the upper example:
| |
| | |
| amtape woo slot 14 # option 1 OR
| |
| amtape woo label B3_14 # option 2
| |
| | |
| amtape will return something like:
| |
| | |
| amtape: label B3_14 is now loaded.
| |
| | |
| After this you can return to your amrecover-session and continue restoring your files.
| |
| | |
| Please be aware of the fact reported by JC Simonetti: " I have never never used the "settape" command of amrecover [with chg-disk] since there's some problems with it (tape not loaded correctly, or impossible to change from tape to tape when restoring data shared accross multiple tapes...) "
| |
| | |
| !!NEW!!
| |
| | |
| Since Amanda 2.4.3 you can let amrecover use the complete changer instead of the currently loaded tape too.
| |
| No need to open a second window to load the correct tape.
| |
| | |
| For this add in [[amanda.conf]]:
| |
| | |
| amrecover_do_fsf yes
| |
| amrecover_check_label yes
| |
| amrecover_changer "changer"
| |
| | |
| With the last line we give the changer a name, which we can use instead of the tape device in amrecover,
| |
| when starting the command:
| |
| | |
| # /usr/local/amanda/sbin/amrecover woo -d changer
| |
| | |
| or from inside with the '''settape''' command or even:
| |
| | |
| Extracting files using tape drive file:/BACKUP2/slots/ on host
| |
| backupserver.local. Load tape B3_14 now
| |
| Continue [?/Y/n/s/t]? '''t'''
| |
| New tape device [?]: '''changer'''
| |
| Using tape "changer" from server backupserver.local.
| |
| Continue [?/Y/n/s/t]? '''y'''
| |