I’m experiencing performance slow down on JBoss 7.1.1 Final. I wrote simple program that demostrates this behavior. I generate an array of 100,000 of random integers and run bubble sort on it. @Model public class PerformanceTest { public void proceed() { long now = System.currentTimeMillis(); int[] arr = new int[100000]; for(int i = 0; i < arr.length; i++) { arr[i] = (int) (Math.random() * 200000); } long now2 = System.currentTimeMillis(); System.out.println((now2 – now) + “ms [...]

The book “HBase: The definitive guide” states that Installing different filesystems on a single server is not recommended. This can have adverse effects on performance as the kernel may have to split buffer caches to support the different filesystems. It has been reported that, for certain operating systems, this can have a devastating performance impact. Does this really apply to Linux? I have never seen the buffer cache bigger than 300 Mbytes and most modern [...]

I have a fileserver with an 8TB volume for which MS DPM is doing a consistency check, its now running 16 hours and it is probably less than 30% through the volume. Why is that so slow? My MS SQL database backups (few hundred GBs) are done in a flash. My DPM Server has 32GB memory and 2* Quadcore 2.4Ghz with a DAS attached that has 24 disks. My file server has 4GB memory and [...]

I looked at http://serverfault.com/questions/2107/tools-for-load-testing-http-servers but I couldn’t see how to replay my own existing logs in any of those tools. I have a bug that only occurs under certain load operations which my existing JMeter and AB testing stuff can’t reproduce. I want to simply give the tool access_logs and have it play them back, either faster or at the same speed. Asked by Stewart Robinson You can use Jmeter’s Access Log Sampler component. There’s [...]

I am trying to copy a 1.2Gb file between a Windows 7 workstation and a Windows Server 2003 system. That same server also hosts our enterprise’s shares, most of them anyway. The copy from the workstation to the server times out. If not in the event logs, where might this timeout event be recorded? Furthermore, what tools exist, other than doing something like running Wireshark, that would let me see the details of the failure? [...]

We have an Heartbeat/DRBD/Pacemaker/KVM/Qemu/libvirt cluster consisting of two nodes. Each node runs Ubuntu 12.04 64 Bit with the following packages/versions: Kernel 3.2.0-32-generic #51-Ubuntu SMP DRBD 8.3.11 qemu-kvm 1.0+noroms-0ubuntu14.3 libvirt 0.9.13 pacemaker 1.1.7 heartbeat 3.0.5 The virtual guests are running Ubuntu 10.04 64 Bit and Ubuntu 12.04 64 Bit. We use a libvirt feature to pass the capabilities of the host CPUs to the virtual guests in order to achieve best CPU performance. Now here is [...]

I have a VPS server (WiredTree), running CentOS. After experiencing some performance issues I created a simple benchmark for disk read/write speed using the following script: echo Write to disk dd if=/dev/zero of=test1 bs=1048576 count=2048 echo Read from disk dd if=test1 of=/dev/null bs=1048576 Here’s a sample output: [bizwayz@host perf]./benchmark Write to disk 2048+0 records in 2048+0 records out 2147483648 bytes (2.1 GB) copied, 11.2601 seconds, 191 MB/s Read from disk 2048+0 records in 2048+0 records [...]

I’m using a remote dedicated server running ubuntu server edition, and I have no idea what the upload/download speeds are. Is there a reliable method to test these speeds via the command line? I know you can just download a file and look at the rate, but that depends on the speed of the hosting server and you don’t get an upload speed =/ Asked by Matt Check out iperf. Just start up iperf on [...]

Have an SBS2011 running Exchange, a database app and a few other things serving 5 users (3 low use, 1 high). The server was never specced for the database app so it isn’t as powerful as I’d like… Only 12GB RAM. We have increasingly found performance problems with this server, last week it was so bad I couldn’t even connect remotely. To free up some available RAM I have (over the past month or so): [...]

Running CPanel and wondering what would be the best for web hosting? deadline is more balanced over CFQ right so would allow for more I/O activities right Asked by Julia Roberts Yes. The CFQ algorithm is intended for process and resource sharing. It is also compatible with ionice. The deadline scheduler is geared towards providing priority to intensive processes. This is easy for you to test. Try it in your environment both ways and see [...]