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

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7
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4answers
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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 ...
7
votes
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 ...
7
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
22k 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
1answer
289 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 ...
7
votes
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
votes
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
3answers
10k views

Does using a large NTFS disk allocation size for a file share make a difference?

I'm formatting a drive using NTFS which will be dedicated as a file share for users to centrally store their files. The files will likely be large (10's to 100's of megabytes). Someone suggested ...
7
votes
1answer
5k views

Remote connection to MySQL server takes very long

I have a MySQL 5.0.75 server running on my Linux notebook to which I want to connect from another machine in the local network. This connection takes 5-6 seconds: mysql -h 172.22.65.101 -u myuser ...
7
votes
2answers
2k views

Can rsync display current average speed?

When I'm transferring large quantities of data using rsync, it would be helpful if I could have the average speed up until now at a glance, rather than a bunch of different speeds for each file.
7
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2answers
313 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 ...
7
votes
2answers
2k views

Logging hurts MySQL performance - but, why?

I'm quite surprised that I can't see an answer to this anywhere on the site already, nor in the MySQL documentation (section 5.2 seems to have logging otherwise well covered!) If I enable binlogs, I ...
7
votes
6answers
3k views

How can I keep Apache from falling over?

I have a pair of servers hosting a single Magento ecommerce site with moderate traffic (60k page views per day reported from google analytics, I think about 80k reported on the server itself). The ...
7
votes
7answers
11k 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
13k 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
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
6k 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
5answers
6k views

FreeBSD jails vs virtualization performance

I'll soon buy myself a nice server (something like the quad-cpu HP DL585) for personal use (home related stuff, data-mining projects, web server and some cron jobs), and I wonder how to separate all ...
7
votes
1answer
153 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
votes
2answers
480 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
432 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
349 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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1answer
2k views

Best practices for choosing fs block size on ext3/4?

I never really pay block size much attention but obviously there can be benefits to choosing something other than the default. I am looking for a good "best practices" paper on choosing block size. ...
7
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5answers
602 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 ...
7
votes
3answers
6k 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
303 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
723 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
1answer
2k views

At what point is EBS usage the bottleneck?

I've got a site hosted on Amazon using a EC2 instance backed by an EBS volume. On the weekends, traffic spikes and I make the instance larger which helps quite a bit -- I'm no longer seeing CPU usage ...
7
votes
3answers
762 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
votes
2answers
494 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
348 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
435 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 ...
6
votes
4answers
17k views

Howto check disk I/O utilisation per process

Im having a problem with a stalling Linux system and I have found sysstat/sar to report huge peaks in disk I/O utilization, average service time as well as average wait time at the time of the system ...
6
votes
9answers
4k views

Linux Server Performance Monitoring

I'm looking to monitor performance on my Linux servers (which happen to be Centos). What are the best tools for monitoring things in realtime such as: Disk Performance I/O, swapping etc.. CPU ...
6
votes
3answers
3k 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 ...
6
votes
2answers
4k views

In absense of iotop which command is most appropriate for get i/o bounded process

Suggest me best way to list io bounded process. I know iotop is best way to get list but want any alternate option since my system showing a large number of D state process.
6
votes
6answers
7k views

Find the bottleneck: disk I/O on Windows XP

One of our development boxes has developed a problem wherein performance will occasionally drop through the floor. When this happens, you can hear the hard drive thrashing, but I don't know what's ...
6
votes
4answers
1k views

Will a database server perform better running on 2 CPUs with 16 cores or 4 CPUs with 8 cores?

What I have: an online financial application (ASP.NET, C#) at peak we have 5K+ simultaneous users backend is running on Oracle 11g (active server + stand-by using Active Data Guard). At peak - 4K-5K ...
6
votes
1answer
1k views

Is it bad practice to run a web application server directly on port 80/443

I am hosting a web app on amazon aws, using an ec2 instance. On that instance i will be running only one application. using glassfish v3.0.1 I do not want to run the app using : ...
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5answers
4k views

How to measure disk throughput?

I want to know how many bytes per second can I write to the disk and read from it. How can I do that on linux machine?
6
votes
2answers
3k views

ZFS with L2ARC (SSD) slower for random seeks than without L2ARC

I am currently testing ZFS (Opensolaris 2009.06) in an older fileserver to evaluate its use for our needs. Our current setup is as follows: Dual core (2,4 GHz) with 4 GB RAM 3x SATA controller with ...
6
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 ...
6
votes
4answers
587 views

Suggestions for recommended file system for Linux server

There are many file systems for a Linux server administrator to choose from. Also, it is not always an easy task to figure out the appropriate layout and optimal file system for your needs. Can you ...