Date: Tue, 12 Oct 1999 10:27:38 -0400 (EDT) From: FreeBSD Bob <fbsdbob@weedcon1.cropsci.ncsu.edu> To: freebsd@planet.nl (Marc Veldman) Cc: a.genkin@utoronto.ca (Arcady Genkin), freebsd-questions@FreeBSD.ORG Subject: Re: Why use tape for backups? (was: backup method reccommendation?) Message-ID: <199910121427.KAA63747@weedcon1.cropsci.ncsu.edu> In-Reply-To: <Pine.BSF.4.10.9910112034130.1603-100000@lurkie.wxs.nl> from Marc Veldman at "Oct 11, 1999 10:48:48 pm"
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> Choosing a backup system and backup procedure is a matter of how fast, > and how much, you want your data to be available. Very good point. Also, it will vary highly between the types of system to be backed up. > You can image that in a very critical system like an AWACS plane in > combat or a nuclear power plant or an airline reservation system, you > would want your most recent data available as soon as possible. Few of us maintain systems on ol' ``Hognose'', as we used to call her. > In most professional environments, people hedge their bets: > > 1.They build a second, completely seperate, out-of-the way > computer system to replace/mirror the first. A very expensive > option. Nevertheless essential for banks, stock exchanges, > military systems etc... You know, I am doing that same thing on the home net, and here at the office. That is turning out to be a very viable solution, and not really all that expensive. Machines, or at least FreeBSD compatible machines are really rather cheap, these days. That's good. > 2.They use a RAID(5) system for single harddisk failures. > Very common. This is expensive for the average Joe. > 3.They make backups to restore accidentally removed files. > (human error is the most common reason for restore operations) > An often underestimated and overlooked problem. No RAID protects > against 'rm -rf /' ..........) > > 4.They keep enough backup media to be able to recover from > (usually human) failures discovered after a period of time > longer than one backup cycle. > > 5.They move their backups offsite to be able to deal with big > failures like fire, theft, riots, tornadoes, whatever. 3/4/5, Everyone should do, although the level at which this is done will be much more intense for a commercial operation than the Home Joe machine. ..... > If your critical data fits on a floppy disk, it can make more sense > to make a daily copy to a floppy disk than to buy a DLT tape robot. > You keep all floppy disks for a month, and then you put them in a > shoebox, and give them your brother who lives a 100 km./miles away. Very true, and one reason for serious consideration of a CD as a potential backup medium, if your average data store AFTER a level 0 backup is less than a CD, OR, you can archive essential files off to CD. I find myself doing a lot of that lately, using my NT cdburner (yikes) as an archival writer of iso cd's of my old hard-to-replace unix systems, and files of a historical nature. It is a pain and takes a lot of time to do it right. Tapes are so much easier, but CD's have a bit more portability than tapes. That means, if I do it right, that I can read restore or archival files from even the wife's windoz 3.1 box, if all else fails. Those machines are not intelligent enough to do that with tapes. ..... An interesting thing that I am finding on the home boxes, and also the work boxes here in the office, is that I can do a base install from scratch, in lieu of a traditional backup and restore, in about the same time or less, off CD or the net, compared to a restore backup from tape. That leads me to tar or dump off only my addins beyond the base install, for backup, as the second level backup, (primarily /usr/local, /etc changes, and that kind of thing), and then personal user files as the third level backup (primarily the home file systems, web file systems, and archival on-line file systems). That is entirely different from a traditional dump/restore level 0-9 style backup, but it works very well on my machines. It is a 3 tiered kind of thing, and then only changeable personal files get backed up regularly, with machine userland addins backed up as necessary when the conscience hurts. I would not handle it that way on commercial systems, but, on lowend home systems or even lowend things like my office systems, that approach works for me. > Backups are a form of insurance. If you want better coverage, you > pay more. (Or you expend more effort.) I'm a tightwad, and never have enough time, so I had to develop the above scenario based upon my own experiences. It works for me as lowendian Joe. I DO always make two backup copies (at least) of anything really important. A singular backup, on any medium, will bite you down the road. Redundant copies on redundant media is always best. > > Is there any reasons tapes are a better choice? > > In a home/personal environment, you might very well get > away with your installation CDROMs and a few floppy > disks with copies of local your local configuration files > in /etc, /usr/local/etc and the like. The only real problem of using floppies is that if it gets beyond half a dozen to a dozen or so floppies you have to manage, ANY form of tape is better, even an old 60mb QIC tape. Still, tarring off certain precious files to floppy, particularly your xinit files and etc files, is just plain good juju for anyone. On FreeBSD, everyone has a floppy, so it is easy to do. > In a commercial environment, there are a lot of reasons: > > If you want to archive files, there is simply no way around removable > media. Harddisk are too expensive. I would contend that even here, CDburning of archive files (i.e., those files you really, really do want to save for a rainy day, but which are not full backup fodder) is potentially as good as tapes, albeit slower. The only constraint is that you have to plan what to fit on a CD's worth of space, or your data to archive has to be less than a CD, by default. Tapes are a lot more convenient. It is probably not really viable on a big commercial system, but is entirely so on a lowendian Joe's machine. ..... > In short: > > If you use your system in a personal environment, your mileage may > vary. At home, I make backups of my most important config files every day > (all right most.., all right usally, .......) > Getting a -stable system back on track usually takes eight hours for me. > I have the habit of frequently wiping one of my personal systems to > practice restores. With the backups of the config files it is a pain. > Without the backups it is a major pain. A spare machine to go through the above motions is great fun and good utility on the home net or lowendian Joe's net. 8 hours seems like a little long. I seem to be able to do that on my boxes in about 2 hours, from a dead machine, provided I can local ftp install, and local ftp restore userland and personal files. You must really have a wild machine, or I am running very plain jane boxes. But, the point is that it is good practice even for the home Joe to have a spare archive machine handy. Machines really are cheap, these days. I have been paying 5 bucks and less for 486 towers that make great local ftp archive sites or spare web servers. It is really easy to do these days, and even gives one networking practice and remote backup capabilities. I have been told from our ``computer gurus'' around here that many Gatesware machines, even lowend pentiums, can't handle the load anymore. I expect a flood of those in surplus, shortly, and that would be great for my (or anyone's) FreeBSD pit....(:+}}... ..... > Sorry for the long reply. > I still have some bruises from some bad crashes. Good points. We all have a few bad memories of lost data. Unix, at least, gives one many alternatives to back things up. Everyone, even newbies, needs to give that some serious thought and action. Bob To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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