todd@lectroid.sw.stratus.com (Todd Joseph) (11/26/89)
I'm performing dumps on a Sun server with an Exabyte 8mm backup system. Dumping to an Exabyte takes a long time. Consequently, performing dumps in single-user mode takes the server out of use for a long time. Does anyone have experience with performing dumps in multi-user mode? Thanks for your help. Todd Joseph
tr@pcharming.ctt.bellcore.com (tom reingold) (12/07/89)
On the subject of "Question about dumps on Suns",
todd@lectroid.sw.stratus.com (Todd Joseph) writes:
$ I'm performing dumps on a Sun server with an Exabyte 8mm backup system.
$ Dumping to an Exabyte takes a long time. Consequently, performing dumps in
$ single-user mode takes the server out of use for a long time. Does anyone
$ have experience with performing dumps in multi-user mode?
It's not "supposed" to be a good thing, since you can lose some files
while you back them up, but it's the only way I do backups, and I
haven't had a disproportionate number of problems resulting from it.
That is to say that the benefit of not taking the system down seems to
outweigh the inconvenience of the occasional lost file.
Tom Reingold |INTERNET: tr@bellcore.com
Bellcore |UUCP: bellcore!tr
444 Hoes La room 1H217 |PHONE: (201) 699-7058 [work],
Piscataway, NJ 08854-4182 | (201) 287-2345 [home]wsmith@umn-cs.CS.UMN.EDU (Warren Smith [Randy]) (12/07/89)
In article <18506@bellcore.bellcore.com> tr@bellcore.com (tom reingold) writes: # #On the subject of "Question about dumps on Suns", #todd@lectroid.sw.stratus.com (Todd Joseph) writes: # #$ I'm performing dumps on a Sun server with an Exabyte 8mm backup system. #$ Dumping to an Exabyte takes a long time. Consequently, performing dumps in #$ single-user mode takes the server out of use for a long time. Does anyone #$ have experience with performing dumps in multi-user mode? # #It's not "supposed" to be a good thing, since you can lose some files #while you back them up, but it's the only way I do backups, and I #haven't had a disproportionate number of problems resulting from it. #That is to say that the benefit of not taking the system down seems to #outweigh the inconvenience of the occasional lost file. # #Tom Reingold |INTERNET: tr@bellcore.com I agree whole-heartedly. A couple of additional notes: a) Since you can generally do exabyte dumps unattended you can dump the whole system in the wee morning hours. Not many people are manipulating the filesystem at 2am. Even though we have many night owls usage is still low. b) Since you can backup the system every day you are almost certain to have a copy of a file valid within 2 days. In practice I can't recall ever not finding files that we needed on the tape I looked for them on. If you have some application running in the early morning hours that does significant filesystem manipulation your mileage may vary... Randy -- Randy Smith wsmith@umn-cs.cs.umn.edu ...!rutgers!umn-cs!wsmith
dworkin@salgado.Solbourne.COM (Dieter Muller) (12/08/89)
In article <18506@bellcore.bellcore.com> tr@bellcore.com (tom reingold) writes: > >On the subject of "Question about dumps on Suns", >todd@lectroid.sw.stratus.com (Todd Joseph) writes: > >$ I'm performing dumps on a Sun server with an Exabyte 8mm backup system. >$ Dumping to an Exabyte takes a long time. Consequently, performing dumps in >$ single-user mode takes the server out of use for a long time. Does anyone >$ have experience with performing dumps in multi-user mode? > >It's not "supposed" to be a good thing, since you can lose some files >while you back them up, but it's the only way I do backups, and I >haven't had a disproportionate number of problems resulting from it. >That is to say that the benefit of not taking the system down seems to >outweigh the inconvenience of the occasional lost file. Which is great until restore(8) decides the dump is corrupted and refuses to have anything more to do with it. We've had that happen a couple of times. Here's what I sent to Todd via e-mail, it may be of more general interest: ========================begin included message======================== Don't do it unless you've added the live filesystem mods from Purdue to your dump. You run a chance of restore not being able to read the tape, the odds being directly proportional to filesystem activity at the time of the dump . This is true even for level 9 dumps, but is particularly painful for the level 0 ones. Unfortunately, this *does* require source for dump. If you have 4.2 or 4.3 BSD source, that version of dump will work just fine. The mods, btw, skip any files that change while dump is running. This translates to some files not getting dumped. Two solutions: A) tell people that things changed between times X and Y aren't guaranteed recoverable, or B) do a level 9 immediately after the level 0 completes. =========================end included message========================= We've made this change internally, and have had occassion to restore from these dumps. You get complaints about missing files, but the entire tape set does get processed. Dworkin -- sophisticate: to alter deceptively; esp. ADULTERATE --Webster's 7th Collegiate boulder!stan!dworkin dworkin%stan@boulder.colorado.edu dworkin@solbourne.com Flamer's Hotline: (303) 678-4624 (1000 - 1800 Mountain Time)