Archive
Posts from 2007
Speeding up Oracle disk I/O on RHEL4 systems
While poking around the web last wek, I came across a good paper from Redhat that describes how to utilize asynchronous and direct I/O with Oracle. I have been using the Oracle filesystemio_options="SetAll" initialization parameter on a few RHEL 4 database servers to efficiently use memory, and had no idea idea that it provided the throughput numbers listed in Figure 2. Nice!
$ read more →Resizing Veritas volumes with vxresize
We were getting close to running out of space on one of our database volumes last week, and I needed to add some additional storage to ensure that things kept running smoothly. The admin who originally created the VxVM database volume only used half of each of the five disks that were associated with the volume / file system that were at capacity, which meant I had roughly 18GB of free space available on each device to work with: GROUP DISK DEVICE TAG OFFSET LENGTH FLAGS datadg D01 c2t0d0s2 c2t0d0 35547981 35547981 - datadg D02 c2t1d0s2 c2t1d0 35547981 35547981 - datadg D03 c2t2d0s2 c2t2d0 35547981 35547981 - datadg D04 c2t3d0s2 c2t3d0 35547981 35547981 - datadg D05 c2t4d0s2 c2t4d0 35547981 35547981 - datadg D06 c2t5d0s2 c2t5d0 35547981 35547981 - Now there are a number of ways to resize volumes and file systems with VxVM and VxFS. You can use vxassist to grow or shrink a volume, and then use the fsadm utility to extend the file system. You can also perform both of these operations with vxresize, which takes the name of the volume to resize, the disk group the volume is a part of, and a size parameter to indicate that you want to grow (you use a "+" to indicate that you want to grow the volume by the value immediately following the plus sign) or shrink (you use a "-" to indicate that you want to shrink the volume by the value immediately following the dash) the volume…
$ read more →Concert review Shadows Fall, Lacuna Coil and Stone Sour
As you can see from my concert review archive, I am a bug fan of hard rock. So when Jagermeister announced that they were sending Shadows Fall, Lacuna Coil and Stone Sour out on the road together, I knew I had to make one of the shows. My opportunity came earlier this week, when I got the chance to see each of these bands for the first time live. Shadows Fall came on stage shortly after a local opening band finished, and played their hearts out…
$ read more →When SSH permissions bite!
Last week I set up several Linux and Solaris hosts to use key based authentication. For some reason two of the hosts continued to prompt me for a password, even though the server and client were configured correctly to used DSA keys (I was using the same config on all of the servers, so I knew it worked). When I traced the sshd daemon on one of the hosts that was misbehaving, I saw the following just before the password prompt was displayed: The strace output made me realize that $HOME/.ssh might not be set to 0700, or the authorized_keys file might not be set to 0600. It turns out the permissions on both entries were set incorrectly, and after adjusting the permissions (which got borked by an incorrect umask entry in /etc/profile), everything worked as expected…
$ read more →Adding swap to Linux hosts
I recently ran out of swap space on one of my production application servers, and needed to add some additional swap on the fly. Since I didn't have a spare slice free on the server, I created a 1GB file on my / file system with dd, and then used the mkswap and swapon utilities to create a swap device out of that file: To verify the new swap device was available, I dumped /proc/swaps: Filename Type Size Used Priority /dev/hda2 partition 522104 160 -1 /swap1.swp file 1048568 0 -2 Sizing swap is easy to do, but when a server changes roles, previous swap estimates no longer come into play. I am planning to kickstart the server with a different disk layout, which will allow me to allocate a block device of the right size to swap. For the interim, this met our needs.
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