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

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Troubleshooting strategy for very poor iSCSI/NFS performance

We have a new Synology RS3412RPxs that offers iSCSI targets to three Windows 2008 R2 boxes and NFS to one OpenBSD 5.0 box. Logging into the RS3412 with ssh and reading/writing both small files and ...
8
votes
3answers
7k views

MSMQ very slow to receive messages

We've got a pretty large MSMQ environment setup which today decided to grind to a halt. (Everything is a VM under vSphere 4.0 Update 1) There are 8 Web Servers which receive data from clients on the ...
8
votes
5answers
659 views

ASP.NET High CPU Bringing Servers to their Knees

Ok, our new build is having 100% cpu spikes on each server at random intervals. For long durations it make the site totally unresponsive - this will be at peak times as people in different countries ...
8
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6answers
522 views

How to grow from single server setup

I'm looking for resources on how to grow our server setup. We currently have one dedicated server with Rackspace in the UK of the following spec: HPDL385_G2_PrevGen HP Single Dual Core Opteron 2214 ...
8
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5answers
6k views

Partial-stroking / Short-stroking / Half-stroking Hard Drives?

Could anyone here explain to me what is implied by this term? (I've seen the same thing mentioned with the 3 terms). At first when I read about it, for some reason I understood that it was some way ...
8
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2answers
3k 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 ...
8
votes
2answers
2k views

Server CPU's: How much does L3 cache size matter when it comes to virtualization?

Performance-wise, how much does the L3 cache size on Intel Xeon i7 processors matter for virtualization functions? I'm picking out a Xeon 1366 Nehalem/Westmere CPU for a server I'm spec'ing to be a ...
8
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6answers
7k 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 ...
8
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3answers
459 views

Adding CPUs puts MySQL 5.5 (Debian) performance down

I am about to setup a database server (MySQL) in OpenVZ container and I've been wondering how many CPUs I should assign to it. I decided to benchmark it. I compared two OS/MySQL distributions and ...
8
votes
1answer
9k views

How should I tune apache when I see high CPU, but low memory usage?

My CentOS web nodes (LAMP stack) are experiencing high CPU usage but low memory usage. Nearly all of the processes are apache. I know I could just add additional web nodes until my cpu usage becomes ...
8
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2answers
2k views

Is there a standard way to benchmark a Windows VM performance from within the guest OS?

We are seeing our software behaving unusually at one of customers where it is being run inside a Windows 2008 virtual machine. The host is VMWare ESX Server. The biggest issue I have seen is our ...
8
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3answers
2k views

Load testing wireless LANs

Anyone have any suggestions for methods of load-testing wireless networks for enterprise network deployments? We've got a wide array of different wireless worst-case scenarios to support. rooms ...
8
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3answers
3k views

Postmaster uses excessive CPU and Disk Writes

using PostgreSQL 9.1.2 I'm seeing excessive CPU usage and large amounts of writes to disk from postmaster tasks. This happens even while my application is doing almost nothing (10s of inserts per ...
7
votes
9answers
5k views

Linux: How to find out whether the harddrive is causing a bottleneck?

I'm not asking how to find out where a bottleneck is. I just what to know how to check if the harddrive is being used at its limit (and hence causing a bottleneck). Something like top where I can see ...
7
votes
6answers
5k views

SMB claimed to be “slow”

Our company network (which I believe is a windows domain run on server 2008) is painfully slow. A prime example of this is copying files over SMB - listings take minutes, and copying even modestly ...
7
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3answers
1k views

How to calculate cost/benefit of hardware expenditures? (move to virtualization, upgrades, etc.)

Preamble: As part of the acquisition of a smaller development company we have acquired a new office. Many people were transferred to head office, but 'new' office will retain a small team of 4-6 ...
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votes
5answers
5k views

Configuring NTFS file system for performance

We have an application that is planning to store around 1.1TB of XML files which average 8.5kb in size. These represent a rolling 18 months of data, with around 200,000 new files being created every ...
7
votes
4answers
23k views

Does the DisablePagingExecutive registry change have any actual effect?

On a number of machines in the past, across different versions of Windows (2000, XP, and no Vista), I've enabled DisablePagingExecutive to try and improve performance. In each case, and I've had ...
7
votes
3answers
4k views

Monitor system CPU / system calls in Linux

I have a couple processes that are eating up a lot of system CPU time (as determined by looking at vmstat). Is there an easy way to find out what kind of system calls are being made? I know there ...
7
votes
1answer
466 views

Why is FileZilla so much faster than PSFTP?

I'm using FileZilla 3.10.3 and PSFTP 0.63 (PuTTY). Can anyone help me figure out why the throughput I get is so drastically different between the two clients? It can't just be a shortcoming of the ...
7
votes
5answers
6k views

Freebsd or Linux? as BGP router over 100mbps

I am building a server to act as a BGP border router for my 100mbps uplink in ISP. I needs these feature: 1) Dual stack BGP peering/routing (at least 100Mbps, maybe more). 2) Potential full internet ...
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4answers
8k views

Gigabit ethernet generally faster than Firewire 800?

If I want to transfer a large file between two computers, which are connected via LAN, would going through the network (setup as gigabit ethernet) be faster than using a direct Firewire 800 connection ...
7
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4answers
3k views

Does using SSL cause a significant performance hit?

I'm trying to decide whether to use SSL for a webapp. It doesn't handle credit cards or financial data, but it does store information that should be private for personal/social reasons. There is also ...
7
votes
5answers
8k views

Linux md vs. LVM performance

I am trying to tune my NAS, running openfiler, and wondering why I'm getting relatively poor read performance from 4 WD RE3 drives in RAID 5. EDIT: Please note I am talking about the buffered disk ...
7
votes
2answers
315 views

Disk latency is growing since a few days ago, with no special change in disk throughput

Here is the disk latency graph of my server. The server has two 5400 RPM 32MB Cache SATA 3.0Gb/s hard drives mounted with software RAID 1 configuration. No special changes has happend in those days ...
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7answers
12k views

Slow NFS transfer performance of small files

I'm using Openfiler 2.3 on an HP ML370 G5, Smart Array P400, SAS disks combined using RAID 1+0. I set up an NFS share from ext3 partition using Openfiler's web based configuration, and I succeeded to ...
7
votes
1answer
17k views

How to troubleshoot latency between 2 linux hosts

The latency between 2 linux hosts is about .23ms. They are connected by one switch. Ping & Wireshark confirm the latency number. But, i dont have any visibility into what is causing this latency. ...
7
votes
2answers
3k views

How do you disable the “last accessed” attribute on NTFS/Windows?

Inspired by this answer, I realize I have no idea how to disable the last accessed attribute in Windows to increase performance. If you can, how? I know in Linux you can mount the partition with the ...
7
votes
4answers
3k views

Experience in migrating from Apache to nginx?

I'd like to get some feedback about a migration From Apache to nginx. My goal is to reduce the memory footprint of the web server. Currently, I use the following modules.features on Apache: multiple ...
7
votes
7answers
7k views

Windows Server 2008 R2 grinds to a screeching halt during file copy operations

When my Windows Server 2008 R2 machine is performing any large disk operations (copying 10GB files from one drive to another, copying similar file over network, merging HyperV snapshots, compressing ...
7
votes
1answer
199 views

What do users see when Apache reaches MaxClients?

Occasionally, in my Apache error log, I will find: [error] server reached MaxClients setting, consider raising the MaxClients setting I've purposely lowered MaxClients in the past (to 60) due to ...
7
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2answers
534 views

Can I have 2Gbit over 1Gbit Nics [closed]

So this really baffles me. Apparently because 1Gbit can transmit data in both directions simultaneously it should be possible to get 2Gbit of data transfer on a single NIC (1Gbit flow seend and 1Gbit ...
7
votes
3answers
522 views

Can gigabit media converters affect performance?

We are looking to upgrade our network infrastructure. We have fiber between our IDFs and our MDF but have found fiber core switches to be significantly more expensive than copper. If we were to have a ...
7
votes
1answer
350 views

SQL Server 2005 Performance Audit

Do you guys have any good step by step type links for performing an SQL Server 2005 Performance Audit? Something like this link would be great but for SQL Server 2005.
7
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2answers
3k views

Importance of disk alignment for Windows Server 2012

I saw article about Disk alignment here and also here.Also there where some references that windows server 2003 has some problem with disk alignment. After reading article I am confused whether we ...
7
votes
3answers
3k views

PostgreSQL slow commit performance

We are having some problems with a PostgreSQL configuration. After some benchmarks I found out that very simple queries are taking a relatively long time, upon furter inspection it appears that the ...
7
votes
2answers
1k views

Linux disable disk cache for a single command

Our server is performing decently, but when backups or other scan processes run it will tank the entire server. Something like clamd will run and scan many files. While we expect slow performance, ...
7
votes
1answer
5k views

Nginx auto minify html output

does anyone know of a way to get nginx (or any other method) to minify html output on the fly? It seems straightforward to me and can shave a few kb off and help speed up the site.
7
votes
3answers
7k views

TIME_WAIT connections not being cleaned up after timeout period expires

I am stress testing one of my servers by hitting it with a constant stream of new network connections, the tcp_fin_timeout is set to 60, so if I send a constant stream of something like 100 requests ...
7
votes
1answer
346 views

virtual disk image - file or partition

I'm looking at the differences between using a file versus a partition to store a virtual disk image in VM use. The common knowledge is that partition-based images are faster than file-based images ...
7
votes
1answer
3k views

How to select the best Stripe Size when configuring a RAID Array

There are various "references" on the Internet that delve into some discussion about what factors to consider when selecting a particular RAID stripe size (4KB to 128KB or more) for an array of disks, ...
7
votes
1answer
1k views

ext3 file system performance tuning: what metrics to monitor

I have a high-IO application that is working, and scaling well to date. Over the past few months we've been trying to look down the road and predict where our next bottlenecks will occur. One of ...
7
votes
2answers
783 views

Does speed of ZFS snapshot rollback depend on number of files?

I have tested a 10Gbit connection between two hosts to be able to read a 10GB file from host1 and write it to host2 using netcat, where the speed was 410MB/s. When I ZFS send/receive again with ...
7
votes
3answers
830 views

Why is there less latency on loopback than on a carp interface?

Stack Overflow Careers is served up something like so: user -> internet -> our fw -> nginx -> haproxy -> web farm FreeBSD is the operating system in use no firewalling or QoS is in ...
7
votes
1answer
4k views

Why the performance decrease for an SSD when using Hyper-V?

I've just installed my new M4 256GB on a Windows Server 2008 R2 Hyper-V server. On the host system using Crystal Disk Mark I've got 212 Mb/s as 4k QD32 write performance, but when I create a VHD disk ...
7
votes
1answer
2k views

windws server 2008 udp multicast performance problem

I encounter a strange performance problem on 2008 R2 Enterprise SP1. Here is the setup: Many processes listening to distinct Multicast UDP streams (5 multicasts listen by process) bound on a single ...
7
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2answers
528 views

Network performance deteriorates when uninvolved device on switch is shut down

I am witnessing very counter-intuitive effect in my network setup. I have a network setup with three devices (let's call them server, laptop and nettop, all running Linux, details below) connected to ...
7
votes
1answer
357 views

RAID with 4 drives offers very minimal speed improvement

Setup 1.5TB x 8 on a SANS Digital enclosure configured into two sets of 4 drives and connected to a Windows Server 2003 computer over eSATA. They are all identical Seagate Barracuda ST31500341AS ...
7
votes
1answer
476 views

sys.dm_exec_query_stats interaction with recompilation

We use sys.dm_exec_query_stats to track down slow queries and queries that are IO offenders. This works great, we get a lot of very insightful stats. It is clear this is not as accurate as running a ...
6
votes
8answers
3k views

SQL Server slow in production environment

I have a weird problem in a customer's production environment. I can't give any details on the infrastructure, except that SQL server runs on a virtual server. The data, log and filestream file are on ...