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#1 2012-09-30 14:43:59

graysky
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From: /run/user/1000
Registered: 2008-12-01
Posts: 8,532
Website

Throughput DECREASE using rsync in deamon mode [Solved]

When I compare average xfers running my backup script over NFSv4 to the same backup directly to rsync running in deamon mode, speeds are on average 1/2 SLOWER going directly to the rsync in deamon mode.  Why?

Option 1
Configuration: Rsync in daemon mode running on the server.
Average xfer speeds: 40 MB/s

$ cat /etc/rsyncd.conf 
uid = root
gid = root
use chroot = no
max connections = 4
pid file = /run/rsyncd.pid
read only = false
hosts allow = 10.1.2.101

[large]
path = /mnt/backup
comment = big drive

Command on workstation:

# rsync -avxu --progress --delete-after --exclude "archives/archlinux*.iso" /mnt/data/ backup@aa::large/drive_data/

Option 2
Configuration: Rsync over NFSv4/no daemon at all.
Average xfer speeds: 90 MB/s

Note that NFS is exporting /nfs4exports/data which is mounted to /mnt/aa_backup on the workstation.

Command on workstation:

# rsync -avxu --progress --delete-after --exclude "archives/archlinux*.iso" /mnt/data/ /mnt/aa_backup/drive_data/

Last edited by graysky (2012-10-01 02:10:22)


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#2 2012-10-01 00:15:57

fukawi2
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From: .vic.au
Registered: 2007-09-28
Posts: 5,283
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Re: Throughput DECREASE using rsync in deamon mode [Solved]

What is the server in terms of specs?

Running in daemon mode, the server has to calculate the rolling hash of the files, and transfer the hash to the client for comparison. When you're running it over NFS, the client does all the calculations, the server is just read/writing blocks on disk, rather than having to calculate complex mathematical formulas.

Hence, if your server is somewhat low-spec in CPU/RAM (such as an off-the-shelf NAS box) then it's easy for it to become overloaded.

My best guess anyway.....

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#3 2012-10-01 02:09:28

graysky
Member
From: /run/user/1000
Registered: 2008-12-01
Posts: 8,532
Website

Re: Throughput DECREASE using rsync in deamon mode [Solved]

It's an Intel Atom (Pineview) so yes, ultra low power.  Thank you for info on the inner workings of these things.  Good know and I think this mystery is solved.

Last edited by graysky (2012-10-01 02:12:38)


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