InstantForum.NET v2.9.0SQLServerCentralhttp://www.sqlservercentral.com/Forums/notifications@sqlservercentral.comWed, 19 Jun 2013 20:00:25 GMT20http://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspx[quote][b]darrenstokes (2/18/2013)[/b][hr]Also checked disks and only seeing 9MB/s writing to the disks, and they're capable of much more obviously.[/quote]Are they? Right now? How do you know?Run a quick benchmark locally and across the purported gigabit link both - [url=http://www.microsoft.com/en-us/download/details.aspx?id=20163]SQLIO[/url] is my favorite quick tool for that, but a basic file copy will work, too. Do it both ways, just in case.Note that when a disk controller loses its cache, or its battery (which almost always then disabled the cache), you can see a sudden dramatic drop in write performance.If nothing else, get the HW folks to run online or offline diagnostics on both ends, the end that's being written to first.Tue, 19 Feb 2013 08:22:55 GMTNadrekhttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxDid you ever find a solution to this problem? I'm also experiencing very low restore rates, less than 1MB/s.The unrestored log has only grown by 94MB in 8 minutes, but mirroring just isn't keeping up.We're running SQL 2012 RTM. We've got a gigabit link between the 2 servers which isn't being touched. Data seems to have been sent to the passive server but its just not applying the transactions to the databases quickly enough.Also checked disks and only seeing 9MB/s writing to the disks, and they're capable of much more obviously.[img]https://docs.google.com/file/d/0B8Na6AcZlqbzUnpqMkhlVzVSYzQ/edit?usp=sharing[/img]DarrenMon, 18 Feb 2013 07:44:44 GMTdarrenstokeshttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspx[quote][b]Marios Philippopoulos (7/21/2012)[/b][hr]Could the slow restore rate be caused by high file fragmentation on the mirror server?Perhaps we are due for a file defrag outage.[/quote]No file level fragmentation would cause a slow degradation of performance, not a sudden one.Sat, 21 Jul 2012 22:55:10 GMTRobert Davishttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxCould the slow restore rate be caused by high file fragmentation on the mirror server?Perhaps we are due for a file defrag outage.Sat, 21 Jul 2012 21:40:11 GMTMarios Philippopouloshttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspx[quote][b]Robert Davis (7/18/2012)[/b][hr]No I meant stop/start the mirroring endpoints. Use an Alter Endpoint caommand and do it on both partners.[/quote]Thanks for clarifying, now I know what you mean; will try that.Wed, 18 Jul 2012 20:56:24 GMTMarios Philippopouloshttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxNo I meant stop/start the mirroring endpoints. Use an Alter Endpoint caommand and do it on both partners.Wed, 18 Jul 2012 09:10:01 GMTRobert Davishttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspx[quote][b]Robert Davis (7/17/2012)[/b][hr]There is also a bug related to this (though I don't know if a KB has been published Try stopping and starting the mirroring queues to see if it resolves the problem. If not, continue investigating and consider opening a case with PSS.[/quote]Thank you for the suggestion. Do you mean suspend and resume the mirroring session? I will try that next time this happens.Wed, 18 Jul 2012 03:04:48 GMTMarios Philippopouloshttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxThere is also a bug related to this (though I don't know if a KB has been published Try stopping and starting the mirroring queues to see if it resolves the problem. If not, continue investigating and consider opening a case with PSS.Tue, 17 Jul 2012 11:11:27 GMTRobert Davishttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxThanks both for your suggestions.Tue, 17 Jul 2012 02:41:46 GMTMarios Philippopouloshttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxI think the above all is sufficient to get the culpritbut mostly It would be Network BandwidthThanksS.R.KundurTue, 17 Jul 2012 00:45:34 GMTksrikanth77http://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxJust some random thoughts:Check the disks for contentionCheck to see if anything else is running on the box and consuming inordinate CPU and/or memoryMake sure your anti-virus software isn't on and attempting to scan your database filescheck the sql server for blocked processesDepending on how far the data is travelling, you might have to have your network folks take a look at the traffic between source and mirrorMon, 16 Jul 2012 15:23:09 GMTDavid Webb-CDShttp://www.sqlservercentral.com/Forums/Topic1330430-1549-1.aspxA production mirroring session started synchronizing this morning and at first the restore rate on the mirror server was at about 30 MB /sec.Suddenly it dropped to < 5 MB /sec and has stayed like this for most of the day.As a result, the mirror has been in "synchronizing" status for most of the day, and we are unable to create snapshots for reporting users.What could be the cause of such a low restore rate? What should I be looking for?Any links/suggestions would be most welcome.Mon, 16 Jul 2012 15:13:41 GMTMarios Philippopoulos