DRAFT DRAFT DRAFT

dmcrypt versus loopaes

  1. the setup
  2. files test
  3. io test
  4. links

For this comparison we examine the speed and cpu load of dmcrypt and loopaes.

question:
Which performs better, dmcrypt or loopaes?
How does software RAID interact with the performance of dmcrypt and loopaes?

conclusion:
Loopaes is faster and puts less load on the cpu in all tests except 'stat' and 'rewrite' using RAID5. However, dmcrypt is often not far behind: either method is a fine choice.

the setup

  • hardware: dual 933 mhz netserver lp1000r, 1.75 GB RAM, 73 GB SCSI disks.
  • benchmark: The bonnie files test and io test.
  • filesystem: reiserfs format 3.6
  • kernel: debian kernel-image-2.6.10-1-686 (-4)
  • dm-crypt: using debian cryptsetup 20050111-2
  • loop-aes: debian package loop-aes-source-2.2d-2
  • cipher: aes256 with essiv hash.
  • scheduler: deadline scheduler (kernel boot param: elevator=deadline).

files test

The values are number of files per second (higher is better), except for "load" which is the average cpu load (lower is better). This graph leaves out the 'random' tests (ie ran_create, ran_delete, ran_stat). We do this to make the chart more simple and our target application (maildir) stores files sequentially. View graph with random tests left in.

(rn = no raid, r1 = raid1, r5 = raid5, dm = dmcrypt, loop = loopaes)

This is the same data, but in terms of percentage. The faster test has a value of 100% (higher is better). The higher load has a value of 100% (lower is better).

io test

The values for put and get K/second (higher is better), seeks are number of seeks per second (?) (higher is better), load is cpu load (lower is better). Seeks are divided by two for RAID1 and RAID5 (otherwise there are twice as many because we count each disk).

This is the same data, but in terms of percentage. The faster test has a value of 100% (higher is better). The higher load has a value of 100% (lower is better).

links

Cipher comparison: aes optimized for i586 is fastest (even in 256 bits).

docs.indymedia.org/view/Local/UkCrypto#Filesystem

clemens.endorphin.org/LinuxHDEncSettings

wiki.boum.org/TechStdOut/LinuxCryptoFS