Archive for March, 2007

VxFS clear blocks mount option

While reading through the VxFS administrators guide last week, I came across a cool mount option that can be used to zero out file system blocks prior to use: “In environments where performance is more important than absolute data integrity, the preceding situation is not of great concern. However, for environments where data integrity is […]

Preallocating files sequentially on VxFS file systems

One cool feature that is built into VxFS is the ability to preallocate files sequentially on disk. This capability can benefit sequential workloads, and will typically result in higher throughput since disk seek times are minimized (LBA addressing, disk drive defect management and storage array abstractions can sometimes obscure this, so this may not always […]

Backing up the Veritas Cluster Server configuration

Veritas cluster server stores custom agents and it’s configuration data as a series of files in /etc, /etc/VRTSvcs/conf/config and /opt/VRTSvcs/bin/ directories. Since these files are the life blood of the cluster engine, it is important to backup these files to ensure cluster recovery should disaster hit. VCS comes with the hasnap utility to simplify cluster […]

Watching slab usage with slabtop

The Linux kernel uses a slab based allocator to allocate kernel memory. Inside each slab is a collection of objects that have been allocated by one or more kernel subsystems. To monitor slab utilization in realtime, most modern day Linux distributions ship with the slaptop utility. When slabtop is run without any arguments, it displays […]

Using the Solaris coreadm utility to control core file generation

Solaris has shipped with the coreadm utiltiy for quite some time, and this nifty little utility allows you to control every facet of core file generation. This includes the ability to control where core files are written, the name of core files, which portions of the processes address space will be written to the core […]

Measuring system call time with procsystime

When debugging application performance problems related to high system time, I typically start my analysis by watching the system calls the application is issuing, and measuring how much time is spent in each system call. Gathering this information is simple with DTrace syscall provider, and the DTraceToolkit comes with the procsystime script to allow admins […]

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