From: Sun Manager (sunfired@gmail.com)
Date: Thu Mar 22 2007 - 17:50:31 EST
Hi Gurus,
I have a system here that has mounted partions for some users to upload
their data. Each user has a fixed space in which they can upload their data.
Users sftp into a chrooted environment to upload their data. One user (my
boss) wants extra space in his area to upload his data. I tried to link a
directory which had enough space from within his work directory, but it will
not work because it is a chrooted environment and he cannot traverse down
the link. I had no other partitions free to mount it onto his work area. So
I thought I had a brilliant idea and proceeded to create a filesystem within
a filesystem and have it mounted to a subdirectory in his work area. Here is
what I did:
There is about 50g free in /usr1
# mkfile 50g /usr1/newpart.ufs
# lofiadm -a /usr1/newpart.ufs
# newfs /dev/rlofi/1
# mounst /dev/lofi/1 /<my boss's work area>/temp
All this worked fine. However there is a big performance hit. Using Bonnie I
tried to test IO on a space of 1Gb and get te following result
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec
%CPU
1024 326 0.7 327 0.2 437 0.6 11973 36.7 148240 85.0 432.8
1.6
Just a few hundred K/sec? That's not acceptable. Doing the same test on a
normal partition yields
-------Sequential Output-------- ---Sequential Input--
--Random--
-Per Char- --Block--- -Rewrite-- -Per Char- --Block---
--Seeks---
Machine MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec
%CPU
1024 35563 77.2 40732 25.4 30640 33.2 33897 99.9 213579 96.5
31582.6 165.8
What explains this poor performance? How can I improve performance on the
new mount point? Am I missing something?
Thanks in advance
--SF
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