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

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2answers
2k views

How to change the scheduler of a RAID 5 device?

I've created a RAID 5 device block by combining 4 HDDs. The name of my device is md1. But the /sys/block/md1/queue/scheduler file outputs "none" on doing cat. And also after editing it using vim ...
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1answer
43 views

Will adding CPU cores or RAM to my cloud server improve speed in my situation? [duplicate]

I have a Siteground cloud server, and I know nothing about servers. It hosts 8 websites, although 3 of them have their own dedicated IP addresses and cPanels. It's on a Linux server, but there's ...
3
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1answer
51 views

Decreased performance of Mysql after superior hardware upgrade

I am quite new to Percona/database servers and i dont know how to approach the following issue. Couple of days ago i upgraded the hardware of a percona cluster (3 nodes) servers with a much more ...
4
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3answers
255 views

Generating a lot of dirty pages is blocking synchronous writes

We have processes doing background writes of big files. We would like those to have minimal impact on other processes. Here is a test realised on SLES11 SP4. The server has massive memory, which ...
1
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1answer
29 views

What is the “right way” to combine sync and drop_caches?

When I need to do echo 3 > /proc/sys/vm/drop_caches with a sync beforehand, is it better to use sync && echo 3 > /proc/sys/vm/drop_caches or sync ; echo 3 > ...
0
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1answer
50 views

MongoDB 80,000+ insertions per second

To test my MongoDB 3.2 / WiredTiger on CentOS6, I use the script from http://vladmihalcea.com/2013/12/01/mongodb-facts-80000-insertssecond-on-commodity-hardware/. Here I list the script (a little ...
0
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0answers
8 views

Is it possbile to cache pdf documents on the netscaler?

I have a file server which gets pretty overloaded quickly because it is serving huge pdf documents. I have a netscaler in my enviroment as well, and I was thinking of caching them in some way on the ...
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0answers
15 views

How do I diagnose an intermittent ADSL issue

A few weeks ago, we started seeing brief intermittent outages of our connection to the internet. Our connection to the internet looks like this: Internet <---> DSL Provider <---> ADSL ...
3
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1answer
339 views

CORAID using only 1 of the 2 available NICs for AoE traffic

We got 6 CORAID shelves in my workplace. On 2 of them I see AoE traffic on only 1 of the 2 NICs that are attached to the SAN switch. We got jumbo frames enabled on all devices. Both NICs show up when ...
1
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1answer
512 views

MongoDB high CPU usage

Running MongoDB 2.4.11 on Ubuntu 14.04.1 LTS In top, this mongod thread is constantly using ~195% CPU: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 24524 mongodb 20 ...
1
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1answer
31 views

Apache - delay over HTTPS but not HTTP

I have a problem with an Apache 2.4.7 on Ubuntu 14.04 (almost default settings), virtual cloud server. On a medium server load (about 2/3.0 cpu usage and tons of free memory) the time for ...
5
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2answers
9k views

Slow disk performance on Azure Virtual Machine

Okay, so first of all, allow me to say that I'm not an operations person, but a developer. So I'm going into a bit of unknown land here, so please bear with me. I would like to use a Azure Virtual ...
2
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4answers
2k views

Is running a VMware Fusion windows VM from a bootcamp partition faster?

Is running a VMware Fusion windows VM from a bootcamp partition faster than using a virtual drive? If so, is the difference dramatic or just 5-10%
2
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2answers
86 views

DRBD terrible sync performance on 10GigE

I've set up a pair of identical servers with RAID arrays (8 cores, 16GB RAM, 12x2 TB RAID6), 3 10GigE interfaces, to host some highly available services. The systems are currently running Debian 7.9 ...
32
votes
2answers
4k views

Why is my bare-metal 16x 2.93GHz cores computer performing poorer than a VPS with 4x 2.5GHz cores?

I have a written a piece of multi-threaded software that does a bunch of simulations a day. This is a very CPU-intensive task, and I have been running this program on cloud services, usually on ...
5
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2answers
3k views

cat /proc/cpuinfo shows 3.00GHz model but 1400.000 cpu MHz?

I ran this command on ssh to see CPU info: cat /proc/cpuinfo And it says: ... vendor_id : GenuineIntel cpu family : 15 model : 4 model name : Intel(R) Pentium(R) 4 CPU ...
0
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1answer
45 views

Router - huge difference in Tx vs. Rx

I have two computers: (B) Banana Pi - 1 Gigabit Ethernet, Wi-Fi (supports 802.11n) (D) Desktop PC - 1 Gigabit Ethernet, Wi-Fi (2x2 MIMO, supports 802.11n) And (R) Mikrotik RouterBOARD RB951G-2HnD ...
6
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7answers
12k views

How many files in a directory is too many? (Downloading data from net)

Greetings, I'm writing some scripts to process images from various photo websites. Right now I'm storing all this data in individual text files in the same directory. The directory is web ...
0
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2answers
138 views

What does negative value of -1 in kB_rd/ and kB_wr/s mean in PIDSTAT command

This is a sample output from running pidstat. minflt/s majflt/s VSZ RSS %MEM kB_rd/s kB_wr/s kB_ccwr/s 49 0 217532 18784 0.01 -1 -1 -1 Can you ...
4
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4answers
232 views

Which VM needs more resources?

I have a physical server which runs 8 virtual machines with virt-manager and kvm. Since one VM is not needed any more, I want to give the remaining virtual machines more resources. I'm looking for ...
0
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2answers
104 views

Reduced performance in mysql after upgrade to 5.6.27

Our application was using MySql version 4.0.24 for a long time. We are trying to migrate it to version 5.6.27. But, on testing the performance on 5.6.27, even the simple selects and updates are 30-40% ...
1
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1answer
180 views

Possible DNS Server memory leak

I have a Windows Server 2012 R2 physical server running AD DS, DNS roles. Very frequently DNS Server process starts consuming a lot of memory. In Task Manager > Details > Analyze wait chain - I ...
2
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1answer
65 views

Side-effects of having different Memory (RAM) in a server? Example 1600 Mhz and 2100 Mhz [closed]

I know that you should always have the same memory clock speed and in best case even the same manufacturer meaning the same RAM Module. But what happens if you use for example the following setup: ...
1
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1answer
155 views

Extremely slow when executing multiple individual MySQL queries

I've been noticing a performance issue in one of my servers running Apache/PHP/MySQL. So I decided to investigate and test it against other servers. What did I do? In three different servers, I ...
5
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2answers
160 views

Page load long stall times. What is this? [closed]

I have been studying the performance of a website I am building, and notice a curious thing that I can't find the answer to: two requests (always the same two) mysteriously have prolonged stalled ...
3
votes
3answers
1k views

Terminal Server disk performance

Our users experience slow session performance at times during normal work hours. Applications (IE, Office Apps etc.) are slow to respond so is switching between them. This problem happens sporadically ...
1
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0answers
13 views

Long Response Times for Reads via FCoE

We're getting some intriguing performance with our new FCoE environment, and I was hoping that people could let me know if what we're seeing is expected behaviour. Our switching environment consists ...
0
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1answer
37 views

Which memory settings to use for this MySQL server? [duplicate]

I've been looking in a lot of places so far but I couldn't find any articles about how much memory to allocate to MySQL based on server size. I am about to deploy a website on a relatively small ...
14
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16answers
11k views

Real time monitoring of MS Windows servers and their services

We have a bunch of large HDTVs in our monitoring office keeping an eye on all of our production equipment. We are monitoring: Cisco routers HP switches HP proliant servers Windows 2003 IIS SQL ...
3
votes
2answers
79 views

Uneven disc throughput in RAID1 configuration

I am having performance issue caused by slow IO in server which has two identical SSDs in RAID1 configuration. By using "atop" noticed that discs usage is no even: DD | md2 | busy 0% ...
0
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0answers
11 views

Varnish ESI Streaming Response - Is it possible NOT to stream the response

We use Varnish (4) in front of an application which contains a few ESI blocks. What we are seeing (as expected) is that varnish streams the response from the server as soon as our backend responds to ...
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2answers
56 views

For php webserver, what is faster, 1x 24-core server or 3x 8-core servers? [closed]

Pricing at Dell, it seems I can either get a single R430 or 3x R220's. The R220's would have 4C/8T processors, giving 24 threads. The R430 would have 2x 6C/12T processors giving again 24 threads. For ...
1
vote
1answer
43 views

How to check what is causing performance issue

[Edit] This question is different than what is suggested by the moderator, I am trying to find out what could have caused the API to become slow because of the few lines of codes. I am not trying to ...
1
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3answers
664 views

Several Cron at same minute

I'm installing a bunch of Magento shops on a webserver. Every website has a cron job that Magento uses to update its stuff -- it takes 3-4 seconds to complete. The instructions tell to set it to run ...
1
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0answers
146 views

Spring Boot 1.2.7, Tomcat, CSS and Thymeleaf = Very Very slow service

I have a Spring Boot 1.2.7.RELEASE web application (with Tomcat embedded) which needs to handle a very high load spike, ~ 10k connections in 4 to 5 minutes on one server (there is actually a cluster ...
1
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0answers
94 views

MySQL overloading CPU at 100%+

My site appears to be getting over 1 million visits today, usually about 20,000 and for me it seems to be near-unresponsive. I've done some sleuthing and optimised Apache, fixed a bug with PHP ...
4
votes
6answers
3k views

How to tell if linux disk IO is causing excessive (> 1 second) application stalls

I have a Java application performing a large volume (hundreds of MB) of continuous output (streaming plain text) to about a dozen files a ext3 SAN filesystem. Occasionally, this application pauses for ...
1
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0answers
13 views

Trend Smart Scan server updates thrash the disk

Every 2 hours, Trend Worry Free business updates Smart Scan. This process requires Trend to thrash through 6 gigabytes of data - this causes two issues The file cache, full of LOB data, is lost and ...
5
votes
3answers
5k views

mysql is not using multiple cpus

Our MySQL server has been using a lot of CPU lately (it's reached 100% several times and stays there for a while) and I noticed that it the CPU load is all on one core of one cpu. I was hoping to ...
1
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1answer
29 views

HDD seq. read performance

I read the specs for one of the latest Hitachi HDD, https://www.hgst.com/sites/default/files/resources/USC10K1800_ds.pdf . It indicates a speed of SAS 12 Gb/s which is 1.5 GB/s. Is it the sequential ...
1
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2answers
26 views

Will a large number of used inodes cause a server to run slowly

I have a server that runs a Magento site. After being alerted that the available inodes were almost completely used up I found that the site had been storing session files and was not removing them. ...
0
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0answers
21 views

Read Speed 50% Slower Than Expected

have an issue with our internal network that I’ve been trying to troubleshoot for the past two days with no luck, wondering if I can get any answers or ideas that we haven’t thought of yet. We have a ...
4
votes
1answer
2k views

CentOS Tuned Equivalent For Debian

Running a few systems, a few are Debian which have been great. I have on the CentOS boxes tuned(tuned-adm) installed and setup for throughput. I searched all over Google and only found some articles ...
0
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0answers
15 views

Web Application hangs but static pages through Apache work

I am running. . . Redmine, the ruby web application, on Windows Server 2008, reverse proxy'd from Apache. I am also serving static pages through Apache at the same time. DB is on a separate ...
3
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2answers
63 views

Linux raid10 on 2 disks

Linux mdadm has some quirks, one of them is building raid10 with only two disks. There are some reports that it's way faster (twice, both in read and write) as RAID1: ...
3
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1answer
172 views

Disk IO Performance Difference — Hyper-V / CSV — Guest vs Host

I have two different Hyper-V 2012 R2 environments that use iSCSI to connect to their virtual machine storage. While the environments are different (one is all 10 GB whereas the other is mixed 1 GB / ...
1
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0answers
23 views

Logrotation performance

One question about logrotation on a dedicated webserver (64gb RAM) with apache and mysql. In high load hours (2k users online every moment) we are experiencing a strange behaviour. As an example, at ...
1
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1answer
230 views

NetBSD web server performance

I am interesting in the difference web server performance between Linux, FreeBSD and NetBSD since I have heard that NetBSD and FreeBSD have the good TCP/IP implementation. As the result, I setup VMs ...
5
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2answers
3k views

Unable to increase the dynamic port range on Windows Server 2008

I'm trying to "tune" the TCP/IP stack on some Windows Server 2008 machines by following the instructions here: ...
0
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2answers
437 views

How to find files with top io on solaris ZFS?

I have a Solaris 10 ZFS based NFS server. The physical disks are more or less at their maximum io rates. Performance is very bad - so we will add spindles. The NFS solely serves as storage for ...