Re: [Duplicity-talk] Excessive Swapping Under Minimal Load

[edgar . soldin]

On 14.05.2013 01:32, Joseph D. Wagner wrote:
> I am trying to use duplicity to backup my /home to an external hard drive
> (usb 2 interface).  After running for a few minutes, my io slows to a crawl.
> My system reports using about 300-400MB of swap, even though only about
> 600MB / 4GB is in use.
> 
> I am trying to isolate the cause.  It may be duplicity in conjunction with
> the particulars of my configuration (see below).  I get good performance
> under normal circumstances.  I am using fedora 18, which has /tmp mounted
> using tmpfs, but duplicity never uses more than 1.0GB - 1.1GB.
> 
> First, is this the correct forum for asking for this kind of help?

depends on where the issue lies. if it's a duplicity bug, yes.

> Second, what information
> 
> The particulars of my configuration:
> sda1 -> win7 hidden boot
> sda2 -> win7 regular
> sda3 -> grub2 boot
> sda5 -> luks swap
> sda6 -> luks ext4 root
> sda7 -> regular ext4 data
> sdb1 -> luks userdata1 -> md raid 0 with userdata1 & userdata2-> ext4 home
> sdc1 -> luks userdata2 -> md raid 0 with userdata1 & userdata2-> ext4 home

what's your duplicity version?

> 
> My thinking in putting md raid on top of luks was that I would be able to
> better use multithreading (2 luks, 1 per physical drive), whereas putting
> luks on top of md raid might create a choke point (1 luks for 1 virtual
> drive).  I'll admit that this might be the problem.  However, it works fine
> under normal circumstances.

wrong list for this topic ;)

> 
> I was hoping someone could help me either 1) isolate what is causing the
> swapping, or 2) tell me what is wrong with my configuration based upon their
> knowledge of how the kernel works.

here you go, kernel mailing list?

concluding:
1. if you are sure you have ram available but your system starts swapping, then 
the kernel does something wrong.
2. try not to use tmpfs for duplicity temp files and see if the issue persists. 
see manpage how to configure that. read also the part on how much temp space 
duplicity needs. my guess is that it simply fills up your /tmp in ram during 
operation.

ede/duply.net