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I have a fileserver with an 8TB volume for which MS DPM is doing a consistency check, its now running 16 hours and it is probably less than 30% through the volume. Why is that so slow? My MS SQL database backups (few hundred GBs) are done in a flash.

My DPM Server has 32GB memory and 2* Quadcore 2.4Ghz with a DAS attached that has 24 disks. My file server has 4GB memory and 2* Quadcore 2.4Ghz with 11 local disks each 1TB configures as RAID 5.

Both servers are running Windows 2008 R2 64Bit. Each server is connected via 1 GB LAN connection

System performance parameters show:

- DPM Server - CPU Load: < 0.1
- DPM Server - Disk read queue length: average < 1

- File Server - CPU load; < 0.1
- File server - Disk read queue length: average 2
- File server - Read bytes per second;  12 hour average=24MB/s, Max=450MB/s
- File server - Outgoing network traffic, average 10Mbps, max 60Mbps

All in all, the performance parameters look OK. I've ordered another 12GB memory for the file server, just in case but I am not sure whether that is addressing the root cause.

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Why did you order more memory, when you haven't shown any evidence that RAM exhaustion is part of your issue? –  Ryan Ries Jan 5 '13 at 2:13
    
The RAM upgrade costs only a few hundred dollars, not worth delaying. With a larger RAM I also hope an increased performance as the file server will be able to use a larger cache. –  Kumala Jan 5 '13 at 5:26

1 Answer 1

up vote 2 down vote accepted

Google FU, according to Microsoft's own engineers, this is a grin and bear it problem as reported jsut as recently as 3/12.

microsoft dpm check slow on large volumes http://social.technet.microsoft.com/Forums/en-US/dpmfilebackup/thread/ff9b8081-68dd-4c0f-8fd4-7b23950c4f20

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Thanks for that link, I did google quite a bit, but didn't come across this article. Looking at it, it becomes very clear: MS DPM is not the way to go for file servers. I will spend a few more days looking into it, if no solution comes (consistency check completes in less than 4 hours on an 8TB volume) then I'll change the backup solution. –  Kumala Jan 5 '13 at 5:30
    
thanks for the answer vote ! –  SmirksWhileWalkingWCabaretGirl Jan 5 '13 at 5:55
    
147 hours and 13 Million files later, still running. –  Kumala Jan 15 '13 at 8:38

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