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Faster file copy than expected
Not complaining, but trying to figure out how this is working. We have a new PS6210xs in a group with a PS6000 attached via 1Gb switches to esxi 5.5 hosts. I moved a Windows 2008 R2 TS guest to the 6210 and left an iscsi data volume on the 6000. The vm has MPIO set up in HIT/ME. I did a folder copy from the iscsi volume to the local drive and got about 60 MB/sec (according to the windows file copy window), which is maybe a bit low but better than we got on just the 6000.
I moved the data volume to the 6210 and did the same folder copy. This time, 700 MB/sec. I know the Windows speed is a pretty rough benchmark, but the folder did copy in about 10 seconds instead of about 90. Since 700 MB/sec (yes, MB, not Mb) is way faster than 2 1Gb ports should be able to handle, is there some sort of Offload Data Transfer taking place? I did this through the windows gui, so I didn't run any special eql commands, and it's 2008 R2, not server 2012. Also, I did the same type of copy job on another 2008 guest with the vm and data vol on the 6210 and got a copy speed of 160 MB/sec, which is more like what I expected.
Anonymous
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April 23rd, 2015 15:00
Hello,
Windows does support ODX, which offloads some of the copy function to storage. So between members or pools the copy will be much faster.
Regards,
Don
trnc
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April 23rd, 2015 17:00
Thanks, Don. It's just that, according to everything I can find, that functionality only exists in Windows 2012 or Windows 8/8.1. I'm running 2008 R2, and no documentation, blog, etc indicates this is possible in 2008, so it's a headscratcher. I'm planning to move to 2012 this year, but until then I'd like to figure out if I somehow enabled something on the zippy server.
I'll keep digging. Thanks.
EvanRowlett
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April 24th, 2015 12:00
ODX is not supported in 2008R2. You can check using the following link:
technet.microsoft.com/.../jj200627.aspx
You'll be able to look at the file system filter drivers.
Honestly, because of the filter drivers, ODX basically doesn't work if you have, say, a backup agent installed, or some antivirus programs, etc. I've found it to be basically useless as a result. However, unmap does work in 2012/2012r2, so no more shrinking volumes.
trnc
172 Posts
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April 24th, 2015 13:00
I've been doing more testing. The file copy speed is inconsistent - sometimes it will be around 100 MB/s and sometimes 700 MB/s. One thing I noticed is that during the slower copy, the Task Mgr networking tab will display the network utilization on the multipathed nics, but during the fast copy utilization remains at 0. So, more evidence that some sort of ODX type thing is taking place, but I still can't find anything about how that can work on 2008 R2. Also, no idea why its slow sometimes and fast other times unless it's the difference between writing to the SSDs and the 10k disks on the 6210.
trnc
172 Posts
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April 24th, 2015 15:00
Thanks, Evan. I realize ODX isn't supported in 2008 R2. That's why I've been asking how I'm getting 700 MB/sec transfer speeds over dual 1Gb NICs. 700 MB/sec is approximately 5.4 Gb/sec, which is almost 3 times as fast as the top theoretical speed for those 2 nics combined.
Some kind of offloading is happening somewhere. Again, not complaining, but really would like to understand.