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

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0
votes
3answers
720 views

How to analyse performance ESXi NFS Copy between datastores

I'm having trouble with ESXi backup/restore performance. My setup: VMWare ESXi 5.0.0 on a HP ProLiant DL 360 G6, runnnig RAID 5 on a P410 SmartArray as SAS QNAP Nas (QNAP TS-809U-RP NAS 8 bays ...
0
votes
1answer
1k views

Why is hash join slow in postgresql 9.1?

I transfered my DB from Postgresql 8.4 to new server with Postgresql 9.1. Size of DB is 9.9GB Data directory is situated on ssd 60GB disk. And server has 16GB RAM and 16 proccessor cores. But today ...
54
votes
22answers
79k views

How to copy a large number of files quickly between two servers

I need to transfer a huge amount of mp3s between two serves (Ubuntu). By huge I mean about a million files which are on average 300K. I tried with scp but it would have taken about a week. (about 500 ...
6
votes
1answer
140 views

Is it possible to process millions of datagrams per second with Windows, using a vendor agnostic API? [closed]

I am investigating if I can implement an HPC app in Windows that receives small UDP multicast datagrams (mostly 100-400 Bytes) at a high rate, using a dozen or up to maybe 200 multicast groups (i.e. ...
0
votes
4answers
247 views

Testing performance from around the world - how do I get a linux shell easily in multiple countries?

We are building a socket based service where latency is paramount, and as such we have servers distributed into 7 data centres around the world. However, whilst we know we're bringing the servers ...
0
votes
0answers
64 views

Taking a thread dump on IBM J9 takes a long time

I'm trying to collect a java core on AIX (java version 1.6). There is only one dump agent configured, which collects a system dump, heap dump and java core on every SIGQUIT, so I used HealthCenter to ...
6
votes
1answer
78 views

postfix performance with lists in main.cf

For defining a list of items to assign to many different options in postfix, you can either use a comma separated list like this: relay_domains = example.com,example.net,example.org or a hash map ...
1
vote
1answer
51 views

Benchmarks for server response time [closed]

I was testing my website’s performance on Google Page Speed and it mentioned the response time at It average between .6-.8 seconds. What’s the optimal server response time that’s acceptable? Is ...
6
votes
2answers
265 views

does adding heaps of drives to a raid 0 increase performance?

does adding heaps of drives to a raid 0 increase performance? i know that two drives in a striped raid will usually be faster than a single drive but will i notice a difference in performance between ...
0
votes
0answers
12 views

Something like Receive Segment Coalescing for UDP

The TechNet page on RSC states: RSC is defined only for TCP connections. RSC does not work with User Datagram Protocol (UDP) and other transport layer protocols. This is of course ...
3
votes
4answers
4k views

troubleshooting really slow login on a (linux) machine

Within the last couple of weeks, any attempt to login to a specific linux server has gotten really slow. Once I've logged in, things appear to run without significant delay, but some other login like ...
4
votes
2answers
607 views

RAID 10 or RAID 1 x 2 for Hyper-V with AD, EXCHANGE on Windows 2008 R2

We have 2 servers which have 6 SATA 7200 disks inside (each). We want to configure both servers so that they will have Window Server 2008 R2 Enterprise installed and on top of it Exchange 2010 x2 (for ...
16
votes
1answer
228 views

Vendor whitepaper says: 5Mpps no prob. I'm already hitting a wall at 120kpps. Where's the bottleneck?

HP's whitepaper on their QLogic (fka Broadcom) NetXtreme II adapters, which includes the specific NIC that I'm testing, states (page 7) that their small packet performance for packets up to 256 ...
11
votes
1answer
6k 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
vote
0answers
589 views

XenServer 6.2 Read Only and Slow Disk I/O

I virtualized a datacenter a few months back and we have a pool of 3 HP DL360 G5 servers, each with 32GB of Memory and dual Intel Xeons. Recently we have been experiencing 2 issues, the first of which ...
8
votes
0answers
115 views

Why higher await time for DM multipath device than underlying device?

We have a CentOS 6.4 based server attached to Hitachi HNAS 3080 storage and observed the kernel remount the filesystem in read-only mode: May 16 07:31:03 GNS3-SRV-CMP-001 kernel: [1259725.675814] ...
1
vote
1answer
36 views

Application Performance & Interrupt Affinity

Quoting the RedHat Performance Tuning Guide 3.3.7. Setting interrupt affinity Interrupt requests have an associated affinity property, smp_affinity, that defines the processors that will ...
2
votes
1answer
40 views

Is there a maximum 'anything' when running a high number of processes on Windows

I have a series of well optimised services written in house using .Net running on many 512GB RAM server (a mix of Xeons including E5-2697 V2 etc). Is there a maximum handle, process, thread count that ...
1
vote
1answer
26 views

SAS direct dual link connection to an embedded LSI Fusion-MPT controller

This is a hardware question. I have a dual-link SAS hard drive and a Intel S5000XVNSAS motherboard without the drive cage option. Recently, I bought a direct dual-link cable in amazon. But when ...
0
votes
2answers
353 views

RAID1 very slow with LSI card and 2x Samsung EVO 850 drives

not sure if I'm checking it correctly, but here is what I have. Desktop, LSI 9260-8i card, see config below. 2x 500Gb Samsung 850 EVO drives. I also have Samsung 830 drive attached to motherboard ...
0
votes
1answer
74 views

Ubuntu Trusty: virt-manager performance over WAN… 40+ secs freezes

I'm using the virt-manager GUI 0.9.5-1ubuntu3 on my laptop running Ubuntu 14.04 against a server located some distance away (same OS) and getting rather unpleasant performance. Laptop-server pings ...
8
votes
6answers
6k views

Is there a point in using Prelink anymore?

Over the years using various linux boxes, I've gotten into the habbit of using prelink ritually to accelerate load times of applications. However, the benefits of running prelink are negated every ...
2
votes
1answer
33 views

Does SAS server rotate always in it's default speed (like 10K, 15K)

I have some concerns about disk throughput in order to plan my SQL Server deployment. I know from experience that consumer SATA disks sometimes go into sleep mode when not used for a longer period. Do ...
5
votes
3answers
8k views

IIS: How to tell if a slow time-taken is due to a slow network connection

According to http://support.microsoft.com/kb/944884, "when a large response or large responses are sent to a client over a slow network connection, the value of the time-taken field may be more than ...
8
votes
7answers
3k views

What tips do you have for speeding up (performance of) a MediaWiki installation?

We have a MediaWiki installation and are getting complaints that it is becoming slower. How can we increase the speed / performance? I have one tip (which I'll add below) but I'm really interested in ...
2
votes
1answer
58 views

How much of a performance does using QEMU virtualization incur on Windows?

How much of a performance does using QEMU virtualization incur on a Windows host, when both the host and vm are running the same CPU? Older articles indicate that using kqemu avoided the slow down in ...
1
vote
5answers
3k views

Possible reasons for high CPU load of taskmgr.exe process on VM?

On a VMware virtual machine which has severe performance problems I can see a constant average of 20+ percent CPU load for the TASKMGR.EXE (task manager) process. The apps running on this server have ...
2
votes
5answers
4k views

How to measure startup time and order of Windows services on boot?

I am not asking how to measure server startup time here. I am wondering if anyone knows of a tool that can measure and show a graph of the startup time and order of all the windows services during ...
1
vote
1answer
354 views

On a system with 64GB mem the Linux Buffer run full while copying with dd to dev null and io stops till manual drop_caches

I am running a server with linux software raid 10. It is a dual CPU system with 64GB Ram. 2x16GB dimms related to each of the CPUs. I want to use dd to backup kvm virtual machines and run into a ...
5
votes
2answers
200 views

raid controller data transfer rate

I'm going to buy an 8-port raid controller for which the declared data trasfer rate is "Up to 6Gb/s per port". The declared connectors are "Two mini-SAS SFF8088". The maximum number of supported ...
1
vote
0answers
30 views

Windows Server 2012 Disk Operations Freezing

I've got 2x brand new Windows server 2012 R2 servers. Fresh install. All Windows updates applied. One on a brand-new physical server, and the other in our VMWare cluster. When I try and perform a ...
2
votes
5answers
5k views

Performance gains of putting Windows pagefile on separate partition (same disk)?

I am making a drive image that will be deployed to several computers, and I'm tweaking it for performance. It is a Windows XP image. Considering there is only one hard drive, will the machine gain ...
8
votes
2answers
263 views

Extreme UDP packet loss at 300Mbit (14%), but TCP > 800Mbit w/o retransmits

I have a linux box I use as the iperf3 client, testing 2 identically equipped Windows 2012 R2 server boxes with Broadcom BCM5721, 1Gb adapters (2 ports, but only 1 used for the test). All machines are ...
13
votes
14answers
12k views

Why would wireless routers become less reliable over time?

I've been curious about this for awhile now. I don't know if I'm seeing a real pattern or not, but having worked with many home office/small office wireless routers for a few years now, I've noticed ...
3
votes
1answer
251 views

High %soft CPU usage during high network load on ixgbe

We have an Intel 82598EB 10GBE NIC. The network load is composed of lot of small sized UDP packets. To simulate a DDoS, from another server we pushed ~100k pps small UDP packet (just some Mbit of ...
2
votes
1answer
50 views

SAN performance too low?

I've noticed my new EMC VNX5200 SAN tends to perform better after "burning in" a partition. By this I mean filling the partition with different junk data and deleting everything a few times. Asked my ...
0
votes
2answers
1k 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 ...
2
votes
1answer
81 views

Are RAID 5 systems suitable for larger disk sizes?

Why is it generally considered that RAID 5 systems are not suitable for larger disk sizes? Is the same true for RAID 6?
-2
votes
2answers
61 views

Why sometimes AWS EC2 works really slow?

I do only one thing one this server - encoding videos by ffmpeg. And sometimes it does work ok, sometimes it's really slow. I run the same command just for a test: $ sudo time ffmpeg -i test.mp4 ...
7
votes
4answers
4k views

Performance difference between ramfs and tmpfs

I need to setup an in memory storage system for around 10 GB of data, consisting of many 100 kb single files(images). There will be lots of reads and fairly periodic writes(adding new files, deleting ...
1
vote
6answers
8k views

SQL Server Instancing: Should I use multiple instances or databases?

I have a reasonable server connected to a SAN which will be running SQL servers for multiples of the same application. There are no security issues with one application being able to read anothers ...
12
votes
4answers
276 views

tcpdump increases udp performance

I'm running a set of load tests to determine the performance of the following setup: Node.js test suite (client) --> StatsD (server) --> Graphite (server) In short, the node.js test suite ...
16
votes
2answers
1k views

Is running permanently in a VMWare snapshot bad for performance?

I understand that the VMWare KB frowns upon long running snapshots mainly due to two things (In my opinion) Taking tons of snapshots can fill up the data store. Snapshots are simply delta files. ...
2
votes
3answers
1k views

Linux vs OpenBSD vmware performance

I wonder what experience others have of running openbsd on top of vmware infrastructure. I have a pretty regular Lighttpd+Mysql+PHP5 setup of 2 vmware guests: -Debian7 Wheezy -OpenBSD 5.2 (this ...
3
votes
2answers
556 views

Questions about storage performance

I would be glad guys, if you can answer me some of my questions about the performance of our storage. The setup HP P2000 SAS with 2GB cache 8x 1TB SATA 7200 RPM storage RAID6 3x hosts with SAS HBA ...
1
vote
0answers
48 views

File IO being slow

I've rented this root server with a RAID1 mdadm software raid setup. Using dd to benchmark the file IO speed it achieves 230MB/s write (default blocksize). Certain tasks such as mysql are way slower, ...
18
votes
3answers
10k views

OpenVPN performance: how many concurrent clients are possible?

I am evaluating a system for a client where many OpenVPN clients connect to a OpenVPN server. "Many" means 50000 - 1000000. Why do I do that? The clients are distributed embedded systems, each ...
4
votes
1answer
2k views

Does increasing the journal size improve performance for ext4 filesystems?

There is an article on linux-mag which says that increasing the size of the journal on ext4 filesystems actually improves filesystem performance for very large partitions. I'm wondering if anyone ...
1
vote
1answer
125 views

What can explain Hyperthreading bringing a server to its knees

In the last year I've had 2 brand new servers that I commissioned where their performance made them unusable. The both servers were Dell R620 servers with 1 processor. One had 6 cores and the other ...
10
votes
10answers
1k views

How does the number of subdirectories impact drive read / write performance on Linux?

I've got an EXT3 formatted drive on a Linux CentOS server. This is a web app data drive and contains a directory for every user account ( there are 25,000 users ). Each folder contains files that ...