Sorry can't suggest much about the usb issue but for such frequent backups, as well as to enable poin-in-time-recovery (PITR) you should consider log archiving. It should also save you heaps of load on cpu, disk, network and postgresql server. -Amos On 11/17/09, Benjamin Smith <lists at benjamindsmith.com> wrote: > I'm having a server report a high load average when backing up Postgres > database files to an external USB drive. This is driving my loadbalancers > all > out of kilter and causing a large volume of network monitor alerts. > > I have a 1TB USB drive plugged into a USB2 port that I use to back up the > production drives (which are SCSI). It's working fine, but while doing > backups > (hourly) the load average on the server shoots up from the normal 0.5 - 1.5 > or > so up to a high between 10 and 30. Strangely, even though the "load is high" > the server is completely responsive, even the USB drives being accessed are! > > Backup script is really simple, run via cron, pretty much just: > > #! /bin/sh > hour=`date +%k`; > pg_dump <options> mydatabase > /media/backups/mydatabase.$hour.pgsql; > > where /media/backups is the mount point for the USB drive. > > Using top to diagnose, nothing seems to be particularly high! IoWait seems > reasonable (10-30%) and CPUs are 0.5%, Idle is 70-90%. Even accessing the > USB > partition while the load is "high" is responsive! > > I'm guessing that something changed in how load average is counted? > > Server Stats: > Late model 8-way Xeon, SuperMicro brand. > CentOS 4.x / 64 (all updates applied, booted after last kernel update) > Kernel 2.6.9-89.0.16.ELsmp > 4 GB ECC RAM > 300 GB SCSI HDD. > Standard Apache/PHP, Postgres 8.4. > > Any idea how to revert to the old load average tracking behavior short of > using a stale and potentially insecure kernel? > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >