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

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27 views

RAID0 : best chunk size for fileserver with average 650KB files

I found out that my server(linux Ubuntu Server 14.04) has probably a to high chunk size for the RAID0, or atleast I think this is an performance issue... The current chunk size is 512K with 4 disk of ...
-3
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1answer
27 views

Nginx can't serve more than 40 concurrent users

I'm testing my Nginx web server (configured with CentminMod) with https://www.blitz.io/ and the server returns timeouts when the connected users are about 40. I can't understand why! It's Nginx, not ...
1
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0answers
74 views

Server RAID0: one hdd is more %busy then the others?

I'm testing 3 servers with RAID0 with 4 disks. During my test I noticed on all 3 servers that one of the hdd's is more %busy and has much higher averige IO wait (almost 4x higher then the other ...
1
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1answer
28 views

Cisco 2901 - IPSec VPN Maxing CPU

We have a Cisco 2901 on the edge of a 100Mbps/100Mbps WAN link which is providing an endpoint for an IPSec VPN to a Juniper SSG 550M. The problem is that we are seeing a max of 'only' 40Mbps over the ...
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0answers
19 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 ...
0
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1answer
38 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 ...
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0answers
20 views

Tools for mesuring performance and memory usage [closed]

i have sometimes some leak of memory in a php application and i was asked to use a tool to mesure the memory usage and to mesure the performance of website ... i google it but all i've found is xdebug ...
0
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1answer
42 views

Slow Upload Speed - CentOS 6

I've been having an issue with my servers upload speed slowing down for the last week. When it first occurred restarting the network service would resolve the slow speeds. The speed would then be okay ...
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0answers
20 views

SQL Server 2012 which user is using Memory and CPU

For sql server 2012 I am looking for a way to see which active user logins are using how much memory and cpu. I have done a search but it seems there is only a way to see aggregates or how much each ...
-4
votes
1answer
54 views

Mysql my.cnf setup for a server with 8gb ram, 2 processors and 1000 concurrent connections [closed]

I have a server with 2 processors and 8gb ram + 8gb swap ram. I have this "my.cnf" config: skip-looking skip-name-resolve table_cache = 2048 ( max_connections * a query that joins x tables, ex: 500 ...
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0answers
9 views

IIS Performance Counters recorded extremely large requests per second value

While I've been monitoring a production IIS server receiving around 1000 - 5000 requests per second almost steadily, I've encountered a few spikes in the performance counter "Requests/sec" and "GET ...
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0answers
27 views

Slow ext4 read performance on 24-drive hardware RAID6

I have a RAID6 configuration spanned over 24 drives (12x directly attached to the RAID card, 12x via external SAS) running on an ARECA ARC-1880IX-12 (fw V1.51 2012-07-04). The RAID makes up one single ...
0
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0answers
20 views

Why first-time reading file from hdd is slower then next ones? [migrated]

I am measuring my HDD speed with a self-written program. (This is a sort of homework, so I don't need recommendations about existing tools to do that). I do it with the following piece of code: ...
0
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0answers
29 views

Commands taking very long time to execute on ssh

Strangely on few on my linux servers, intermittently, when i try to login through ssh and run commands, they take about 15-30 secs to execute every command. Every commands is executed very slow. But ...
0
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0answers
9 views

Dynamics CRM 2013 on premise workflow performance

We are speaking of the time it takes for the workflow state machine to notice that task A is complete, thus satisfying a wait condition in a workflow definition, which then creates task B. User1 ...
0
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1answer
50 views

Strange CPU spikes with MySQL

On my server (ubuntu 12.04) mysqld started to show some strange CPU spikes. I've logged some of it as a sample: http://pastebin.com/4MwKUVwL The value after the triple dash '---' is the cpu usage ...
0
votes
1answer
40 views

RAID6 generates quite a IO wait at relatively low TPS

I have a RAID6 array made of 9 SATA3 disks @7200 RPM, 4TB in size. I have them partitioned with Gparted Live as GPT partitions, starting at the first megabyte. I am concerned about the read speed. ...
0
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1answer
37 views

Sql Server 2012 Disk I/O Too high

I am running SQL Server 2012 on windows azure VM Windows server 2012. This is a live Database, about 250GB, with high usage. I applied some best practice articles for the temp-db long ago, and also ...
1
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0answers
51 views

Random server load spikes, number of tasks doubles, CPU/Memory consistent

We run a vBulletin forum with 6,000 visitors per day on an SSD VPS with 5GB RAM and 24 CPU Cores. On a typical day we see 30-50 concurrent users at any given moment. On busy mornings, it'll go up to ...
2
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0answers
43 views

“Nosy Neighbor” and the CFQ scheduler

I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem. I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all ...
8
votes
1answer
300 views

How do I run my PowerShell scripts in parallel without using Jobs?

If I have a script that I need to run against multiple computers, or with multiple different arguments, how can I execute it in parallel, without having to incur the overhead of spawning a new PSJob ...
1
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0answers
31 views

Using Azure for application performance testing

I have some custom system management scripts/applications that I would like to performance test against a large number of systems (10,000+) in an effort to simulate larger-scale enterprise networks. ...
1
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1answer
32 views

DFS slowly and using a lot write speed on sender member

I am transferring 400gb of multiple files trough 2 server whit 10gb connection inside one VLAN. When I had 2 servers that were not in production the transfer was very quick using 100% of 1gb ...
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0answers
31 views

AWS CPU Impact on Nginx Webserver

Following these links: Why does top report a different cpu usage than CloudWatch? http://www.metamul.com/blog/measuring-cpu-usage-from-within-ec2-it-doesnt-mean-what-you/ ...
0
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0answers
20 views

Azure Variable Table v Temp Table

This is a bit long; but I have been working through queries figuring out where a performance issue is coming from. Appreciate you taking the time to read it. I have an application running on a ...
1
vote
1answer
99 views

Will a SSD storage perform like a magnetic for small root volumes in AWS EC2?

I have a t1.micro instance with 8GB of magnetic EBS volume as it's root disk with a LAMP environment on it. I thought that I will upgrade it to t2.micro with 8GB of General Purpose SSD volume. ...
0
votes
1answer
62 views

Why this server is so slow?

I hired a VPS in DigitalOcean, it's hosted in Amsterdam, I'm in Turkey. But server is responding slowly and page is freezing/lagging even at ajax POST-GET request.(there is a basic browser game in ...
3
votes
2answers
183 views

Windows Firewall - blocking IP address ranges en masse - performance considerations?

One of our services is an extranet for the exclusive use of our 200 employees across the UK. We're seeing a huge number of login attempts from China, Russia, Ukraine and Nigeria. I have large lists of ...
0
votes
1answer
38 views

Server is not responding when single connection is blocked

I'm not sure how to properly specify this problem, I'm not really a server expert. I will be glad to provide additional data on demand. I have a PHP web-application running on Ubuntu Server with ...
4
votes
1answer
138 views

HDD is acting up, but S.M.A.R.T says everything is fine

Before I begin, a quick disclaimer. I'm basically a developer forced into a sysadmin role by circumstances, so I apologize in advance if I say something stupid or seem like I don't know what I'm ...
5
votes
1answer
125 views

Why iperf still reports 1Gbps performance when using bonding over two 1Gbps adapters?

As I understand it, bonding brings among other benefits the ability to increase the network speed between two machines in a LAN. Bonding [...] means combining several network interfaces (NICs) to ...
2
votes
1answer
52 views

Linux filesystem page cache - hot or not

How can you tell how much of the filesystem cache is hot (frequently accessed) or not? The use case would be determining when you are approaching the limits of your memory but before you actually hit ...
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0answers
16 views

Solr Query thread limit

While performing stress tests of our website, it looks like Solr could be bottleneck. It has enough ram, CPU usage is far from 100%, but we still facing problems of waiting for solr response for even ...
2
votes
2answers
55 views

TCP under OpenVPN is very slow (tsg attached)

I have a very weird problem with OpenVPN. Most VPNs work fine, except this one. Here I get very low performance from TCP connections, but the CPU load is low (so, not a CPU issue). OpenVPN is ...
-1
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1answer
41 views

Innodb performs IO Operation when idle

I am currently doing some stress testing where I am pushing inserts to the database as fast as I can. The simulation inserts 10000 records per second. After inserting around 200 million records I ...
4
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3answers
1k views

Why do servers have SAS instead of SSDs? [closed]

I was wondering why do servers still come with SAS disks instead of SSD disks? I know that SAS are faster than normal hard drives but they are still much slower than SSDs. I think they are more ...
0
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1answer
26 views

How do I know website slowness is related to network or my server

I do know that my php pages generate in less than 0.1 seconds. And also I do know that apache max clients has not been ran out. And website is slowness is confirmed by testing from different ...
0
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0answers
39 views

Nginx : Images takes too long to load. (1sec to download a 50KB image)

I just switched from Apache to debian 7.6 nginx php-fpm and after running all kind of optimisations it seems that it takes a lot longer than usual to display images : The application is extremely ...
0
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1answer
110 views

SCOM alert: The threshold for the Logical Disk\Avg. Disk sec/Transfer performance counter has been exceeded

We are monitoring several Windows Server 2012 R2 VMs running on Hyper-V. Now SCOM (2012 R2 UR2) reports: The threshold for the Logical Disk\Avg. Disk sec/Transfer performance counter has been ...
-1
votes
1answer
29 views

Child process runs in normal priority only. Why? [closed]

I run a scheduled task in Windows Server 2008 R2. I used the technique described here to set its priority to high priority (level 1 of 7). My task runs a process (an EXE file) that creates child ...
0
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0answers
35 views

clonehd takes 2 hours for a 100GB disk. Expected?

I have a VirtualBox image using VDI and flexible size. Right now the physical DVI file 94GB. The host is an Ubuntu server and the guest is a CentOS 6.4 with ext4 partition. The host is using a sata ...
0
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0answers
61 views

Tunning nginx/php5-fpm : why low memory usage with 800 users?

I did optimize nginx with what I found on the internet My specs are 2 servers load balanced : Intel Xeon E5-1620v2 (4c/8t 3,7 GHz+/3,9 GHz+) 32 Go DDR3 ECC 1600MHz 3x 160Go SSD Intel DC S3500 SATA3 ...
0
votes
1answer
96 views

How to speed up QEMU on Windows host?

We want to run our Ubuntu 64bit web server virtualized/emulated on a Windows 64bit host. Intended use is to distribute the VM to customers who might not have "elevated" or "admin" rights on the ...
3
votes
2answers
62 views

Performance associated with storing millions of files on NTFS

Does anyone have a method / formula, etc that I could use - hopefully based on both current and projected numbers of files - to project the 'right' length of the split and the number of nested ...
4
votes
4answers
65 views

Setting the noatime flag for filesystems inside an lxc container

My host filesystem is ext4 mounted with the noatime flag. But inside an lxc-container, the flag is absent. Here's the output of mount on the host: /dev/sdb1 on /home type ext4 (rw,noatime) And ...
0
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0answers
35 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 ...
6
votes
0answers
55 views

Fast distributed filesystem for a large amounts of data with metadata in database [closed]

My project uses several processing machines and one storage machine. Currently storage organized with a MSSQL filetable shared folder. Every file in storage have some metadata in database. Processing ...
0
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1answer
13 views

Why perfmon for remote desktop servers get an empty file (only time stamp)?

I'm trying to remotely monitor a server using perfmon, the output file is always empty and only the time stamp field is there?
3
votes
1answer
92 views

Why would zfs performance be bad for moving files within an fs?

On my FreeNAS NAS (9.1.1 running zfs v28), I am getting terrible performance for file moves between two directories in the same raidz fs. Is this expected? How can I fault-find this, if not? The ...
0
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0answers
39 views

When I should ignore apr_socket_recv: Connection reset by peer (104) in ab test?

I encountered the well-known apr_socket_recv: Connection reset by peer (104) error during my ab test against my server. But I noticed there is a '-r' option in ab which means Don't exit on ...