03-03-2013
Unless you have replaced the standard UNIX sync command with something else, it will not start any database operations. The only thing the standard sync command does is schedule flushing of file system buffers to disk. On a large server with a huge amount of memory, flushing those buffers to disk may literally take an hour depending on the disk speeds and I/O data paths. While scheduled flushes are being processed, the system may indeed be sluggish.
Many database systems perform synchronous writes to be sure that data for completed transactions is safely stored on the underlying files rather than just sitting in buffers to be flushed later. It doesn't sound like your database software does this. If transactions are flushed when they are completed, there will be a small performance penalty at the end of each transaction (and you data would be safe if a power failure or other calamity occurs later), but you wouldn't suffer the big hits you're seeing now. Note that the sync command does not wait for data to be flushed before it returns; it just schedules the flush and returns letting the OS perform the flush to disk while it continues to process other requests.
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LEARN ABOUT DEBIAN
pam-script
PAM-SCRIPT(7) Miscellaneous Information Manual PAM-SCRIPT(7)
NAME
pam-script - a PAM module that can invoke scripts within the PAM stack.
SYNOPSIS
pam-script.so [onerr=(success|fail)][dir=/some/path/]
DESCRIPTION
pam-script allows you to execute scripts during authorization, passwd changes, and on session opening or closing.
Such scripts can perform necessary tasks or influence the outcome of the PAM stack. For example, if the following entry was included in
pam.conf
sshd auth required pam_script
then if the script, pam_script_auth, exits with a non-zero value this would cause the user to be denied SSH access to the machine.
OPTIONS
A summary of options is included below.
onerr=(success|fail)
the default behavior if the module can not find or execute the script. The default is to fail if the option is not given.
dir=/some/path/
where to find the pam-scripts to invoke for each of the various module-types as described below. The default is dir=/usr/share/lib-
pam-script if not given.
List of scripts
pam_script_auth
Executed under auth which handles the authentication stage of establishing the user via some challenge-response (i.e. username/pass-
word)
pam_script_acct
invoked under account module-type for non-authentication based account management.
pam_script_passwd
invoked under passwd for changing the password tokens.
pam_script_ses_open
invoked when a session is first opened.
pam_script_ses_close
run after a session is first closed.
All the scripts will be passed several environment variables: PAM_USER, PAM_RUSER, PAM_RHOST, PAM_SERVICE, PAM_AUTHTOK, PAM_TTY, and
PAM_TYPE referring to the module-type. The pam_script.so arguments in the pam.conf will be passed on the command line, which can be
used to modify the script behavior.
FILES
/lib/security/pam_script.so - the PAM module
/usr/share/libpam-script - where the scripts should be placed by default
VERSION
pam-script 1.1.5
SEE ALSO
PAM(7) and the PAM "The System Administrators' Guide"
AUTHOR
pam-script was written by Jeroen Nijhof <jeroen@jeroennijhof.nl>
with some additions and modifications by R.K. Owen, Ph.D. <rkowen@nersc.gov>.
This manual page was written by R.K. Owen <rkowen@nersc.gov>,
for the Debian project (but may be used by others).
August 22, 2007 PAM-SCRIPT(7)