Fw: re-exporting nfs

Fw: re-exporting nfs

[Yuki]

Hi，
I know ceph can re-export nfs protocol,but there are something confuse me during the test. Here is the command I used.
"dd if=/dev/zeof of=/mnt/ceph/test.bat bs=4M count=1000"
The results are as follows:
ceph:62 MB/s
nfs:26MB/s
There are 3 OSDs,1 MON and 1 MDS in the ceph cluster. And I do this test using the in-kernel client.
I was confused by two things during the test on nfs.
1. The "dd" command will call mknod to create a file,but mknod will creates a FIFO, character special file, or block special file with the specified name.(It will call lookup_open to create a file during the test on ceph,)
2.There are sometimes no network traffic during the test on nfs.(I use the command "sar" to monitor the local LAN network traffic )
Thanks in advance!
Cheng.

Re: Fw: re-exporting nfs

[Gregory Farnum]

On Saturday, April 9, 2011 at 11:45 PM, Yuki wrote:
Hi，
> I know ceph can re-export nfs protocol,but there are something confuse me during the test. Here is the command I used.
> "dd if=/dev/zeof of=/mnt/ceph/test.bat bs=4M count=1000"
> The results are as follows:
> ceph:62 MB/s
> nfs:26MB/s
> There are 3 OSDs,1 MON and 1 MDS in the ceph cluster. And I do this test using the in-kernel client.
> I was confused by two things during the test on nfs.
> 1. The "dd" command will call mknod to create a file,but mknod will creates a FIFO, character special file, or block special file with the specified name.(It will call lookup_open to create a file during the test on ceph,)

I'm not quite sure what you're asking here? We don't have anything to do with maintaing dd so if you're asking about that program I really can't help you. ;)

> 2.There are sometimes no network traffic during the test on nfs.(I use the command "sar" to monitor the local LAN network traffic )

I'm not personally very familiar with the nfs exporting, but my guess is that maybe some of the writes are being buffered up on the export machine and then streamed out from there when it gets a commit from the NFS client.
In general it wouldn't surprise me if NFS re-export is a little slower than native Ceph since NFS routes everything through a single machine while Ceph talks directly to a lot of the servers. You might experiment with a few of the other dd settings (to adjust data sync, etc) and see how that changes your results.
-Greg




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Re: Fw: re-exporting nfs

[Tommi Virtanen]

On Sun, Apr 10, 2011 at 02:45:19PM +0800, Yuki wrote:
> I was confused by two things during the test on nfs.
> 1. The "dd" command will call mknod to create a file,but mknod will
> creates a FIFO, character special file, or block special file with
> the specified name.(It will call lookup_open to create a file during
> the test on ceph,)

This is pretty much out of topic for Ceph, but I figured I'd just
clarify this: an mknod(2) call with mode specifying S_IFREG creates
regular files.

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