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Slow SCSI Connection
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Professional Poster
Join Date: Mar 2004
Location: UK
Status:
Offline
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Hi all.
Got an Intel Xserve with a UL5D SCSI card in it and two big RAID towers. They are currently daisy chained together on a single channel.
I am copying a big pile of data from one RAID to the other but its dog slow. Currently its managing about 10-12GB per hour.
The total is 2.4TB in 850,000 files. Does that sound like the correct speed to anyone? It seems pretty damn slow to me.
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MacBook 2.0GHz CD; MacBook Pro 15" 2.4GHz Late '08; PowerMac G4 MDD Dual 1GHz; 3x Xserve G4 1GHz; Mac Mini 2GHz; Big pile of broken and working bits;
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Administrator 
Join Date: May 2000
Location: California
Status:
Offline
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Only a bit over 3 MB per second. Sounds very slow ... but 850K files is a lot. All small files? Has the source array been used for a long time - ie, heavy fragmentation?
The time may be getting burned doing endless seeks.
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Clinically Insane
Join Date: Mar 2001
Location: yes
Status:
Offline
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How about tracing this starting on your Mac by running "iostat" to see if the disks are being saturated, or if the saturation is happening somewhere else (bus/card, transport, etc.)? In particular, the load averages will tell you how much the disks are being stressed.
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Professional Poster
Join Date: Mar 2004
Location: UK
Status:
Offline
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Must have been file sizes. I think the source RAID is a temporary stand in so not long in use. Shouldn't be too fragmented. Its picked up the pace a bit now. ETA has dropped from 175 hours at the start to 41 hours. It did 70GB in 6 hours but has done a further 250GB in the last 2.
Thanks for the help anyway. A day I can live with but a week is not conscionable.
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MacBook 2.0GHz CD; MacBook Pro 15" 2.4GHz Late '08; PowerMac G4 MDD Dual 1GHz; 3x Xserve G4 1GHz; Mac Mini 2GHz; Big pile of broken and working bits;
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Dedicated MacNNer
Join Date: Oct 1999
Location: Phoenix, AZ
Status:
Offline
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I would agree. File size can have a lot to do with data transfer performance. It takes more work for the CPU, OS and disk to open and close lots of small files, than to do that for a few large files, and shuttle out a lot of data in between file open and closing.
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Chris Brown
Media, Brand, and IPTV Consultant
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Professional Poster
Join Date: Mar 2004
Location: UK
Status:
Offline
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Turned out it was finding around 150000 files that totalled about 75MB.
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MacBook 2.0GHz CD; MacBook Pro 15" 2.4GHz Late '08; PowerMac G4 MDD Dual 1GHz; 3x Xserve G4 1GHz; Mac Mini 2GHz; Big pile of broken and working bits;
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