Enabling circular logging during working hours?

Hi,

quick ones, I need to clear out some transaction logs temporarily (nevermind the reasons):

1. Is there any longer downtime involved (except restarting Exchange services)?

2. Also, will the logs start deleting themselves right away or I will have to wait for many hours (I've 26Gb of logs)

3. Once the logs have been written into the DB, I want to enable them again (and run a full Exchange backup)
Is there any downtime after disabling circular logging (apart of restarting the services)?

thanks!
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septembahAsked:
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Narayan_singhCommented:
Exchange doesnt play the logfiles to the database unless u play them manually (soft recovery) or mount the database.
they are there incase datasbe is dirty so that they can be played later... database is not written from log FILE TO db IT IS FROMMEMORY TO db.

the shortest way to delet the log is dismount the store and delete the logs (you migh wanna check db health before deleting though (eseutil /mh)if it is clean go ahead.)

Just configuring circullar logging to delete the log will not cause harm.restart info store after enabling it and as gupnit said exchange will take care of them.

However circullar logging is not recomended for recovery because if you enable logging logs for stm files will not be written.



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Glen KnightCommented:
No, once you enable circular loggin you will have to manually remove the logs.
The best thing you can do is do a FULL backup of the information store, this will flush all the logs.
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septembahAuthor Commented:
that's the actual problem - I cant do the backup now (no space)
my question is: is there any downtime or I can safely do this within the working hours?
Then, after the logging is enabled how will I know these have been written into the database so I can safely remove them?
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Narayan_singhCommented:
You will have to restart the information store after enabling circullar logging and that the only downtime.
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Glen KnightCommented:
Then do the backup from a different server.
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gupnitCommented:
Hi,
  • Enable Circular Logging
  • Restart Services
  • Exchange will take care of Log File refresh on its own
Cheers
Nitin
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AkhaterCommented:
jut to confirm what Narayan_singh is saying all you need to do is restart the information store
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septembahAuthor Commented:
@demazter: I use online backups and don't have this much space it's not an option. I will have the space back once I get rid of the logs
@gunpit: when you say "Exchange will take care of the logs", do you mean it will flush the old logs itself? Just trying to match it with previous answer that I need to manually go and remove it
If so, I am repeating the question: how will I know Exchange has finished writing my 20Gb of logs into the database, so I can go and manually delete them?
Plus I will need to know if I can delete ALL of them or leave the recent 5 (I read in M$ article it circulates among 5 log files only)
thanks guys and sorry for all these questions but there's no messing with the exchange..


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gupnitCommented:
Hi,
Yes it does. If you are really concerned, run a Full Backup using a Exchange Aware Backup SW and it will flush out all Logs. Then enable Cicular Logging
Cheers
Nitin
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gupnitCommented:
No you do not touch any Logs yourself !!!
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Glen KnightCommented:
As far as I was aware if you enable circular logging the log files will remain until you run a full backup!
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gupnitCommented:
Though you did mention - I still ask - Why? Reason? Well we might provide you a more logical alternative (if possible)
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Glen KnightCommented:
DO NOT MANUALLY DELETE ANY LOG FILES!
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gupnitCommented:
Well Logs will clear automatically :-) ! A good read: http://www.msexchange.org/articles/Exchange-log-disk-full.html
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Glen KnightCommented:
I bow down to your superior knowledge ;-)
Still I don't enable circular logging very often except when I am migrating mailboxes.

I would much rather have proper backups.
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gupnitCommented:
Hey Glen - We all are the same :-) !!
As far as CL is concerned - It is a strict NO for all my customers !!
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septembahAuthor Commented:
let me try it this evening and will let you know how I got on
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gupnitCommented:
@ Septembah - No Worries...:-) !!
@ Narayan - Thanks for summarizing what we discussed !
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Narayan_singhCommented:
since you just want to get rid of the logs ....dismounting database and then running eseutil /mh ".edb path" (just to be on safe side) if clean shutdown deleting all logfiles will be good option for long run do not enable logging.
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septembahAuthor Commented:
right - Before: I have three mailbox storages.
All three have separate folders for the logs. I had to remove half of the logs (20Gb) from the third folder (no space).
After:
I enabled the circular logging and restarted the Exchange services. All folders have been cleared and have only few MB each.
Now, I still have the original (20Gb) bunch of logs I had to move elsewhere earlier on. How can I "write them" back into the database?
I am thinking now of disabling the circular logging, copying these logs back into original logs folder, enabling the circular logging again, so they get flushed properly. Does this make sense?
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gupnitCommented:
Septembah - I am not sure of your objectives here....! Is this some sort of a lab, where you are just testing things !
Why did u move Logs in the first place? Now there will be inconsistencies if u copy back those half logs. Ignore and disable CL, you should be fine.
THanks
Nitin
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gupnitCommented:
Obviously restarting services is one of them !
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septembahAuthor Commented:
it's not testing I'm afraid...
The reason (I'm writing this fourth time), was the lack of space, I don't touch the logs unless things hit the fan. Been away for three weeks, someone's left, something broke, etc. the usual murphy's law hit in.


Anyways, I just made the backup of the full database. The half logs I copied back were not flushed and will probably not get flushed ever because the original references are gone - I suppose I can delete them manually now?
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Glen KnightCommented:
If you had removed them and then placed them back then they are redundant logs, just move them somewhere else, dismount and remount the store ( to check they are not needed) then you can delete them.
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septembahAuthor Commented:
just in case you think the question's abandoned - I will try the above tonight
had 24/7 uptime requirement lately and couldn't dismount the stores the check
cheers
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gupnitCommented:
Cheers !
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septembahAuthor Commented:
hi,
I figured instead of me coming back here every second day with "can't dismount the store now, will try later" I'll just wait until I can actually go ahead and do it - done so only recently.
I eventually managed to perform an old school tape backup which did not flush the old logs either (full exchange backup) so in the end removed the old logs manually (since there were both old and the new ones mixed up together in the same MD folder I used Total Commander compare directories tool).
Re the split points, it's difficult to say who should get it - think the closest to my case were the Narayan's and demazter's answers so to be fair I'll go 50/50.
Many thanks to everyone involved though!




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