+1 And remember that I/O is more than just disk. The atop monitor gives you information like top and htop, but also provides a lot of I/O information as well including network. Perhaps your server is the target of a network-based DDOS attack which can cause lots of I/O wait time. Also look at top to see what numbers are in the si and hi columns. THese stand for software and hardware interrupts. If one of those is high you can also narrow it down. Hope this helps. On 01/28/2015 07:51 AM, Nicolas Thierry-Mieg wrote: > On 01/28/2015 01:32 PM, Jatin Davey wrote: >> Hi Users >> >> I am using RHEL 6.5 on my server. >> >> From top command i can see that the processors in my server are >> spending a lot of time on wait for I/O. >> I can see high percentage in terms of 30-50% on "wa" time. >> >> Here is the df output about the disk space in my system: >> >> ********** >> [root at localhost images]# df >> Filesystem 1K-blocks Used Available Use% Mounted on >> /dev/sda1 1915071844 103227908 1714563936 6% / >> tmpfs 32931472 0 32931472 0% /dev/shm >> ********** >> >> Could someone point me on how to improve the disk I/O on my server and >> reduce the wait time on I/O. > > you could use iotop or vmstat to see what processes are causing the IO. > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > > -- > > > ********************************************************* > David P. Both, RHCE > Millennium Technology Consulting LLC > Raleigh, NC, USA > 919-389-8678 > > dboth at millennium-technology.com > > www.millennium-technology.com > www.databook.bz - Home of the DataBook for Linux > DataBook is a Registered Trademark of David Both > ********************************************************* > This communication may be unlawfully collected and stored by the National > Security Agency (NSA) in secret. The parties to this email do not consent to the > retrieving or storing of this communication and any related metadata, as well as > printing, copying, re-transmitting, disseminating, or otherwise using it. If you > believe you have received this communication in error, please delete it > immediately. >