Questions about server hardware and software performance, or network performance.

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2
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5answers
2k views

Why does this SQL run so much faster in a Oracle server with the same hardware/data than another Oracle server?

My application has a SQL that takes ~ 30 min to run in the Oracle server in production. It takes about the same in a test Oracle server. For some reason, in another Oracle server, it runs much ...
1
vote
1answer
123 views

How to troubleshoot an unresponsive server

I'm performance testing my Java based web application (Grails) that is deployed on Tomcat. The server has the below services running on it: Apache HTTPD Apache Tomcat MySql RabbitMQ Even though I ...
2
votes
5answers
3k views

Downloads pause and time out frequently

I'm a new systems and network admin. My experience has been in the hardware and software of systems and servers, the network part is pretty new to me. I'm familiar with plugging numbers into network ...
1
vote
3answers
8k views

Trouble interpreting iostat's tps measure

Prelude: I dumped a 5.2 GB database using the mysqldump command. I did this on an underpowered virtual server with only 512 MB of memory. It took about an hour. I'm now reloading that database on my ...
0
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2answers
614 views

How is the average seek of disk estimated given a function to move head to n track

How is the average seek time of disk calculated if a function f(x) is given as an estimate of time to move head of disk to n tracks?
3
votes
2answers
559 views

Which part of of a hard drive has the highest throughput, beginning or end of drive?

If I create a partition at the end of the drive does that create the partition on the outside of the platter where the data is passing under the drive heads fastest?
1
vote
1answer
388 views

ssd performance against hdd performance

I have two server, one with a SSD, one with a HDD. I've been running hdparm to see the differences, but the results for Timing cached reads and Timing are quite equal/HDD is faster: SSD: Timing ...
32
votes
12answers
25k views

Is virtual machine slower than the underlying physical machine?

This question is quite general, but most specifically I'm interested in knowing if virtual machine running Ubuntu Enterprise Cloud will be any slower than the same physical machine without any ...
4
votes
5answers
24k views

Disk IO slow on ESXi, even slower on a VM (freeNAS + iSCSI)

I have a server with ESXi 5 and iSCSI attached network storage. The storage server has 4x1Tb SATA II disks in Raid-Z on freenas 8.0.4. Those two machines are connected to each other with Gigabit ...
4
votes
6answers
12k views

IO Wait causing so much slowdown (EXT4 JDB2 at 99% IO ) During Mysql Commit

I am writing an indexer, using python, which indexes documents and insert them into Database, Before it was single process but now i made it to multiprocessing with 4 parallel processes running.After ...
0
votes
2answers
95 views

TCP - TAP performance

Linux. Is there a performance loss from using a tap device vs a hardware one like eth0 ? The goal is to create a user space tcp/ip stack and avoid the kernel as much as possible. I would like to be ...
0
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0answers
36 views
0
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1answer
181 views

How to improve the speed of FTP directory listing with proftpd on Debian 7.5?

I install proftpd on a VPS running Debian 7.5 hosted on Linode.com. The server location is in California (US) while I am remoting from Singapore. The server is on SSD and I am using ADSL 100Mbs ...
1
vote
2answers
151 views

Performance Tuning Linux [closed]

Performance Tuning/ Monitoring/Latency keeping in mind I see following 4 items & in each item they are lot of tools. CPU Memory IO Network What I see following tools we do use. vmstat mpstat ...
2
votes
1answer
169 views

Azure IO performance sql server [duplicate]

We are in the process of migrating our on-premises sql server to Azure and I am having trouble with the IO performance. I have created a new D14 instance and attached 16 virtual disks at 100GB in ...
1
vote
1answer
97 views

Got more RAM, site slower [closed]

I was running my site on 256MB of ram with 2 cores and it was running ok, but I decided to upgrade to 1GB and 4 cores but now my site is slow.. I mean it takes more then 22 seconds to load 1 page.... ...
1
vote
1answer
82 views

Advice on web server performance troubleshooting is needed

I'm renting a virtual CentOS based server where I have about 5 active sites running. Several months ago I noticed a significant performance degradation in how my sites are running. First symptom was ...
1
vote
1answer
297 views

Apache CentOS Server very slow! Wrong configuration?

I have a problem with server overload on a Apache configuration 8gb of RAM 1and1.com Virtual Server. Server gets extremely slow once it reaches 100+ active users (according to google analytics) during ...
0
votes
0answers
116 views

Packet loss between windows guest and Ubuntu 14.04 host

We are seeing packet loss between one of our Ubuntu 14.04 hosts and a KVM guest running Windows 2008 R2. The loss only shows up at high loads. Similarly loaded machines running 12.04 do not exhibit ...
0
votes
1answer
158 views

Improve openvpn bandwidth Debian 7

I configured openvpn on a dedicated server. Things are working fine but the bandwidth is not as high as it should be given the network specifications : The dedicated server has 250Mbps DL speed and ...
1
vote
1answer
60 views

Read performance of old LTO-2 tape

I have a stack of old LTO-2 tapes, and my task is to save the contents as large binary files on disk for eventual consolidation on newer media. (The contents are in a custom format specific to this ...
-1
votes
2answers
68 views

Parallel disk seek with JBOD

I'm looking to build a 80 TB file based storage system. Ideally, I'd like to do this with a large JBOD and one server with a lot of cores. My question is: Will JBOD containers (like Intel's) allow ...
17
votes
2answers
1k views

How are CPU time and CPU usage the same?

In the Wikipedia page for CPU time, it says The CPU time is measured in clock ticks or seconds. Often, it is useful to measure CPU time as a percentage of the CPU's capacity, which is called ...
1
vote
0answers
2k views

MySQL Workbench InnoDB Buffer Usage at 100%, always

The InnoDB Buffer Usage graph is always at 100%. I believe this started to happen when I changed MySQL's temp folder to a much bigger drive, does that make sense? I suppose the thing to do in this ...
0
votes
1answer
63 views

Optimize .htaccess file

I'm trying to optimize my .htaccess file to avoid performance issues. In my .htaccess file I have something that looks like this: RewriteEngine on RewriteCond %{HTTP_USER_AGENT} bigbadbot [NC,OR] ...
1
vote
1answer
115 views

Tuning Linux TCP for large number of TIME_WAIT

It looks like we have a bunch of tcp connections hanging around on a busy webserver, this is the output from ss -s: Total: 366 (kernel 1037) TCP: 72108 (estab 130, closed 71964, orphaned 0, synrecv ...
2
votes
1answer
51 views

Performance-wise, is a DNS Slave better to have than two duplicate Masters?

I have two bind9 servers that are not setup with duplicate settings and know nothing about each other. Our CPU usage is sitting around 7% - 10%: mostly bind, which I believe is perfectly in range for ...
0
votes
1answer
111 views

Why is Win Server 2012 slow to read data with RAID 5?

We have new HP 350p server with 4x 900GB 10k SAS disks with RAID 5 (win server 2012). But disks performance to read data is to slow - it's to slow to read big directory structure on disk. Where can be ...
0
votes
2answers
796 views

Squid proxy performing extremely slow and sometimes doesn't work at all

I recently installed Squid on my desktop machine for testing purposes. I didn't edit the config whatsoever, and just pointed firefox at the proxy to see if it was working. Pages take an insanely long ...
1
vote
1answer
31 views

slow file server with contradictory values for CPU and CPL in atop

I've got a fileserver (centos 6.3) that slowed down suddenly earlier today. The cluster that mounts it could access other NFS mounts without a problem, but the access to this one was VERY slow. ...
1
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0answers
156 views

NGINX using 100% of the server CPU when testing with Blitz.io

I'm facing an issue here and after four days of looking around I decided to ask for some help here, after all a million heads can think a lot better than one. I have a Ubuntu 14.04 server setup with ...
1
vote
0answers
26 views

Improve read performance on ext4 on Centos with software raid1? [duplicate]

I'm running a number of MongoDB nodes on dedicated servers running Centos6. Each machine has two SSDs which I have in Raid1 with two logical partitions: # df -h Filesystem Size Used Avail Use% ...
1
vote
1answer
55 views

Strange Disk Benchmarking results for our storage, how to explain? [closed]

I recently tested the storage we got from our hosting provider. I don't know what raid config or how many disks the storage contains of. I used Atto Disk Benchmark which sends smaller and bigger ...
2
votes
2answers
237 views

Linux virtual memory tuning to workaround disk I/O issue

I am having a problem with a Linux server that it is writing to much to disk, thus I am having a slow response time due to a big IO wait. I already check smart values for the disks and are OK. This is ...
1
vote
2answers
45 views

What is the difference between truss -D and truss -E?

I am currently analyzing a command on Solaris that reads from a file and has very low performance. The truss -D commands shows me read system calls taking up to 0.03 seconds, but when I use truss -E, ...
1
vote
1answer
494 views

Ubuntu Server 14.04LTS Swappiness for server with 16GB memory

(don't worry I'm not asking what my setting should be, asking for the theory behind some conflicting advice I've read) My application is one that is lightweight and not under much load, but needs to ...
-2
votes
2answers
405 views

fastest way to transfer small files (faster than scp) [closed]

Scp is quite slow for transferring individual files. What is the quickest way to do this? The reason I need speed is not because I have a large number of files to transfer. I just want the individual ...
1
vote
2answers
2k views

Per process I/O accounting on AIX

Is there a way of getting per process I/O statistics on AIX, i.e. to get current disk I/O rate of a process? Commands like iostat, nmon, topas etc. can't display such data. Filemon also doesn't help. ...
1
vote
1answer
154 views

Website performance sluggish - High CPU and Disk Usage

Over the past couple of days my website's performance has been very sluggish, with queries taking a lot of time to execute. My CPU usage hit around 100% 4 times this week. Here is the output of top at ...
0
votes
1answer
153 views

What is the counter type for Linux's /sys/block/$DEVICE/stat

What are the counter types for /sys/block/$DEVICE/stat? $ cat /sys/block/sda/stat 8323741 42381356 464031898 19207478 1940738 49062039 408122282 79935459 0 22315734 99172579 Specifically, ...
0
votes
1answer
72 views

Measure Dedicated Server Performance

I run an online video streaming site and keep getting more and more dedicated servers. Our business traffic fluctuates on an annual cycle which allows us to scale back our dedicated servers during the ...
0
votes
1answer
99 views

PostgreSQL queries slower than before?

I am using PostgreSQL 9.3 server on my production server. Everything had been working fine for the past couple of months. But since the past week or so, PostgreSQL seems to have becomes very slow with ...
0
votes
0answers
77 views

What happens on an SQL Server when a snapshot is taken by VMWare?

Recently I saw in our SQL Server logs that a snapshot could not be taken at the specific time and he retried it later on. During that timespan we had a huge performance problem. Besides the SQL Server ...
-1
votes
1answer
487 views

Would cPanel or Plesk slow down my site/server? [closed]

My senior sysadmin told me that if I install cPanel or Plesk (or other panel) on a client's machine as it would slow down the server/site (WordPress on LAMP). This doesn't seem to make logical or ...
0
votes
0answers
28 views

Capacity planning of messenger server [duplicate]

This is regarding a messenger server being developed. This will have thousands of users connected and will be able exchange messages. Users will also be able to send messages intended for multiple ...
0
votes
1answer
718 views

How to solve performance problems with VMware ESXi 5.5 on old Dell PowerEdge 2900 hardware [closed]

I have a couple of old Dell PowerEdge 2900 servers that have come free and I would like to use them to host a mail server cluster. They are a bit old, but have been running workhorses for a while, ...
3
votes
2answers
271 views

iozone: 5 concurrent threads random read of 300K blocks does more ops/s than using only one thread, what could be the underlying reason?

The partition is in RAID1 using software RAID. Command line used: iozone -s 190g -r 300k -O -b test_file OPS Mode. Output is in operations per second. ...
2
votes
0answers
344 views

Cannot set 1G speed on 10G nic using ethtool

I have a linux server with 10G fibre nics: xyz@xyz48:~$ sudo ethtool p1p1 Settings for p1p1: Supported ports: [ FIBRE ] Supported link modes: 10000baseT/Full Supported pause frame use: ...
0
votes
1answer
305 views

Is it safe and efficient to install HHVM on top Apache server with nginx as reversed proxy?

I've been trying to optimize my VPS for WordPress performance, and today, I decided to take it to a new level: I'm thinking about installing HHVM. Server status: My server runs Apache, and I have ...
3
votes
3answers
847 views

How to find virtualization performance bottlenecks?

We have recently started moving our C++ build server(s) from real machines into VMs. (MS Hyper-V) We have some performance issues that I've currently no idea how to address. We have: Test-Box - ...