Raw IO and Direct IO are both bypassing file system cache. Here are more details about these two IOs. This can help us understand the difference and troubleshoot easier when we get a file system issue. Difference Between RAW IO and Direct IO Raw I/O is issued directly to disk offsets, bypassing the file system …

This article is part of the following series. 6 performance tools you should know in Linux 5 Ways to Check disk size in Linux 4 Ways to Check Disk Partition with Examples in Linux How I Fixed a disk performance issue in Minutes – A Step by Step Guide to Optimize Linux System   Disk …

Find command on Linux is a very powerful tool to search files or directories. We can use maxdepth/mindepth to limit down the search to specific depth levels. How to Use Depth In Find Command We can combine two options together to limit the search only between max/min depths. On Centos, there is no option for …

Linux IOwait is a common Linux performance issue. Today we will look at what iowait means and what contributes to this problem. Hope this can give you more ideas about high IOwait issue. IOwait on Linux The iowait column on top command output shows the percentage of time that the processor was waiting for I/O …

DNS is a very critical part of the Linux operation world. We will cover the most common DNS records today. All domains are required to have at least a few essential DNS records for a user to be able to access their website using a domain name. A PTR CNAME MX TXT SRV AAAA DNS …

The most efficient way to check DNS records in Linux is using dig command. This command will send the DNS query to the name servers listed in the resolver(/etc/resolv.conf). It allows you to query information about various DNS records, including A record, MX record CNAME record etc. The following commands can be used to check …

How to get HBA WWPN on Linux is a common task for a storage engineer. We need the WWPN to configure zone on the switch side.We will look at this question today. In our SAN environment, we have two HBAs installed on the Linux system. We can get the HBA WWN/WWPN using the following way …

On Linux disk SCSI ID uniquely identifies each SCSI device on the SCSI bus. A unique SCSI ID is generated when a scsi disk is added to Linux system. SCSI ID can be used for representing a disk in the configuration file because the disk name like sda sdb sdc may change after a server …

How to open a port on Linux is a common question when testing a firewall-related problem. In this article, we will use nc command and Python code to open a TCP port manually on Linux and check if this port is working or not. Methods to open a port in Linux The following Linux commands …

Tcpdump is a very powerful Linux command to capture packets. We collect the following tcpdump command examples to help you quickly filter the packets you need. How to filter ipv6 ntp ping packets with tcpdump? Filter packets larger than the MTU # tcpdump -i eth0 greater 1500 Filter ping packets # tcpdump -s0 -i eth0 …