Archive
Posts from 2007
Viewing SCSI mode page data
I came across the sdparm utility while surfing the web last weekend. This super useful utility can be used to display and modify SCSI device parameters, and is the best tool I've found for dumping SCSI mode and VPD pages. I wish sdparm would have been around when I was reading through the SBC documentation on the T11 website. That would have been swell!
$ read more →Using the Solaris process tools on a specific thread
In Solaris 10 the ptools (process tools) were enhanced to display data for specific threads in a process. This functionality can be tapped into by appending a slash and a thread id to the ptool command line: This is extremely useful when you need to interrogate a specific thread in a process (e.g., a thread that is consuming 100% of a CPU), or when a process has 100s or 1000s of threads (which is typically the case with Java applications). Nice!
$ read more →Monitoring the ZFS ARC cache
The ZFS file system uses the adaptive replacement cache (ARC) to cache data in the kernel. Measuring ARC utilization is pretty straight forward, since ZFS populates a number of kstat values with usage data. Neelakanth Nadgir wrote a cool Perl script to summarize the ARC kstats, and a sample run is included below: Since numerous discussions have come up on zfs-discuss regarding ARC sizing (the size of the ARC is controlled by the zfs:zfs_arc_max tunable), folks will find the "arcsz" column extremely useful. Nice!
$ read more →Enabling the DTrace hotspot provider after the JVM starts
While debugging a JVM performance issue a while back, I encountered the following error when I enabled the DTrace hotspot provider: After a bit of debugging, I figured out that the jinfo command needs to be run by the user the JVM runs as. Hopefully this will help others who encounter this annoying problem.
$ read more →Stopping nfsmapid from querying DNS TXT records
With the introduction of NFSv4, user and group identifiers were changed to use the username@domain format. On Solaris hosts, the domain is determined using the following methods: The NFSMAPID_DOMAIN variable is checked in /etc/default/nfs DNS is queried for the_nfsv4idmapdomain TXT record The configured DNS domain is used The file /etc/defaultdomain is consulted If a site doesn't update the NFSMAPID_DOMAIN variable when deploying NFSv4, DNS will be queried for the domain to use. If the DNS server doesn't contain a_nfsv4idmapdomain TXT record, you will see failed queries similar to the following: This can of course pose a problem for large sites, since the DNS server will be inundated with queries for records that don't exist. If you want to stop these DNS queries from happening, you can add the domain to the NFSMAPID_DOMAIN variable in /etc/default/nfs…
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