LinuxQuestions.org - Performance difference between sharing disk space via NFS or SSHFS

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Performance difference between sharing disk space via NFS or SSHFS

I have a "poor man's" cluster, i.e. 10 boxes connected via 1Gb/s switch and am trying to use for simple MPI calculations. So far I have used sshfs to get a shared disk space on the machines but it seems that the calculations scale worse than I expected. Is there a huge penalty with using sshfs rather than sshfs?

@plesset, Please correct your question, It is confusing. Performance is Degraded in which ? nfs or sshfs.

sshfs is actually using ssh protocol so all the traffic is moving in encryption and decryption cycle so there must be a penalty on performance.
whereas nfs send data in cleartext so performance always better in compare of sshfs.

Sorry for the confusion. I'm using sshfs (since it is easy and I know how to) but I find the performance to be disappointing. So I think I should be using NFS but I'm not sure how to configure it, especially since all the machines are directly linked to the internet. Will using hosts.allow & hosts.deny be enough? I could also ask the network admin to block all access to all but one. Now there is only ssh access to the machines.

You can specify which IP address(es) you want to allow NFS connections from in /etc/exports. Having the machine on the internet shouldn't be a problem as long as you don't set up /etc/exports to allow NFS connections from anybody.

NFS is dead easy to set up.
It's very reliable and efficient.

You have a private sub net connecting the machines just specify
connection only on that. i would assume you will have a central data bank
and connect your calculators to that.

Have you read about GlusterFS
For what seems to be your purpose, it seems like a good alternative do nfs and sshfs.

I installed NFS and map the shared space as

Code:

toppond:/home/xxxx/fds /home/xxxx/fds nfs rw,rsize=16384,wsize=16384,hard,intr,async,nodev,nosuid 0 0

in fstab.

When I test it I actually find it to be slower than SSHFS (especially when writing)...

Code:

> time dd if=/dev/zero of=/home/xxxx/fds/test bs=16k count=16k

16384+0 records in

16384+0 records out

268435456 bytes (268 MB) copied, 4.91929 s, 54.6 MB/s



real    0m5.015s

user    0m0.000s

sys    0m0.160s



time dd if=/home/xxxx/fds/test of=/dev/null bs=16k

16384+0 records in

16384+0 records out

268435456 bytes (268 MB) copied, 2.31482 s, 116 MB/s



real    0m2.317s

user    0m0.008s

sys    0m0.120s

Code:

> sudo umount fds

[sudo] password for xxxx: 



> sshfs toppond:/home/xxxx/fds fds



> time dd if=/dev/zero of=/home/xxxx/fds/test bs=16k count=16k

16384+0 records in

16384+0 records out

268435456 bytes (268 MB) copied, 3.42332 s, 78.4 MB/s



real    0m3.457s

user    0m0.000s

sys    0m0.244s



> time dd if=/home/xxxx/fds/test of=/dev/null bs=16k

16384+0 records in

16384+0 records out

268435456 bytes (268 MB) copied, 3.53909 s, 75.8 MB/s



real    0m3.560s

user    0m0.004s

sys    0m0.072s

Where have I gone wrong?

well there you go.
seems quite fast to me.
why do you think it's wrong? it is what it is.

i prefer sshfs because it is almost as fast as nfs and easier to use (it can also mount directories outside of your network).

maybe the pc's (updates/load) or routers (firmware) or nic's (drivers) are just slow (bad cables) ?

this thread seems to be slow/ bad hard drives which is hampering network performance:
http://www.linuxquestions.org/questi...ts-4175449064/

Thank you all. At least I have gone through and it is always beneficial to learn something new and now I have the option to use both. Given the hassle with setting up/configuring NFS, as compared to SSHFS, I assumed the gain would be greater.

I wouldn't call it done right there, from the looks of it you only tried one small transfer with one block size. Try a larger file (at least 1GB+) and try different block sizes to see how that affects things. Also do each test a few times to make sure the results are consistent.

Also make sure there is no other I/O on either system during the tests if you want the most fair comparison.

There is SSHFS/NFS read/write benchmark: http://prokop.uek.krakow.pl/projects/fs_benchmark.html