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

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How to optimize performance for MSSQL databases?

I'm a dba with a database with ~280 tables, and total datasize of ~1,5GB. I'd like to tune the database to make it perform better. What do you do to keep your SQL databases performant? How much ...
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7answers
2k views

setup lowcost image storage server with 24x SSD array to get high IOPS?

I want to build let's name it a lowcost Ra*san which would host for our social site the images (many millions) we have 5 sizes of every photo with 3 KB, 7 KB, 15 KB, 25 KB and 80 KB per Image. My ...
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7answers
10k views

Speeding up rsync over smb

I'm backing up a Linux box over SMB to a NAS. I mount the NAS locally and then I rsync a lot of data (100GB or so). I believe it's taking an awfully long time to do it: more than 12 hours. I would ...
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5answers
780 views

Command-line: What is this machine?

is there a standard command-line for linux answering a description of the server (model, number of cores(?), speed(?)...)? Thanks, Pierre
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12answers
1k views

Optimum way to serve 70,000 static files (jpg)?

I need to serve around 70,000 static files (jpg) using nginx. Should I dump them all in a single directory, or is there a better (efficient) way ? Since the filenames are numeric, I considered having ...
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5answers
771 views

Linux: how many disk I/O does it take to read a file? How to minimize it?

According to this paper on Facebook's Haystack: "Because of how the NAS appliances manage directory metadata, placing thousands of files in a directory was extremely inefficient as the ...
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4answers
3k views

How do I configure RAID 5, especially stripe size, with 24 x 1.2 TB drives for CentOS 6?

For a Dell R920 with 24 x 1.2TB disks (and 1TB RAM), I'm looking to set up a RAID 5 configuration for fast IO. The server will be used to host KVM VMs that will be reading/writing files of all sizes, ...
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3answers
467 views

Should I host my entire web application using https?

Actually my only requirement for using SSL encryption is that when a user logs in, the password is transferred encrypted. However after reading a bit about protocol switching, that an HTTPS session ...
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6answers
582 views

Sysadmin performance metrics?

I work at a dot com and part of our team's responsibility is to maintain the production web application and server farm. Only recently did our department even get created, and now we have a huge ...
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4answers
10k 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 ...
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8answers
7k views

Hard Drive Speed: RPM vs. Cache

When trying to choose a SATA magnetic hard drive (not SSD) for high performance for both random and linear access, which should be the primary factor? For example: would a 10k RPM drive with 16MB ...
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4answers
7k views

Virtual Machine guest optimization tips

I've installed Windows7 in VirtualBox 2.2.4 and worked like a charm. But compared with my WindowsXP virtual machine, the performance is slow. I've installed Windows7 in (non-virtual) machines and the ...
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6answers
838 views

How to do periodic Sql Server performance monitoring and troubleshooting?

What are the best tools and processes for periodically monitoring and troubleshooting sql server performance issues?
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2answers
3k 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.
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4answers
539 views

Is there an advantage to load balancing using multiple VMs all on the same hardware?

Some collegues are suggesting a web load balancing schema with multiple web servers (IIS7) on different virtual machines all running on the same hardware. Is this a truly advantageous setup? All ...
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votes
2answers
6k views

Clustered indexes versus non-clustered indexes?

I am in charge of a smaller DB 300+ hundred megs 100'ish tables about 45 users hit it throughout the work day. Mostly reads, but a fair number of updates and inserts. I have been slowing learning the ...
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4answers
3k views

dd vs. secure-erase for reconditiong SSDs

Does writing zeros to an entire ssd (dd if=/dev/zero of/dev/sdX) give the same performance restoring effect that you get from a "secure erase", or does secure erase do something else as well? ...
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5answers
5k views

Hyper-V Requirements, disk partitioning

My rule of thumb for a physical server was fast random access disk (VelociRaptor/SSD) for OS, and large disks for data (e.g. WD Caviar). How does that look for a Hyper-V that should run two virtual ...
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7answers
2k views

What is faster? A local mechical hard drive or a solid state drive over gigabit ethernet?

SSDs are rather new, so I couldn't find this information on the Internet. Would the performance of a local hard drive connected using SATA2 get out performed by a SSD over gigabit ethernet? In terms ...
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3answers
8k views

What KVM disk type to use?

I'm setting up a few KVM virtual guests and I'm debating which disk type to use. I haven't been able to find a good resource online that runs down the pros and cons of each. Can you help me create a ...
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1answer
789 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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3answers
6k views

mkfs Operation Takes Very Long on Linux Software Raid 5

I've set-up a Linux software raid level 5 consisting of 4 * 2 TB disks. The disk array was created with a 64k stripe size and no other configuration parameters. After the initial rebuild I tried to ...
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4answers
534 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 ...
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4answers
644 views

Geographical DB synchronus mirroring

An architect in our company has designed a solution based on 64 bit SQL2005 Standard edition synchronous mirroring between a physical (4 quad core, 32GB RAM) server and a virtual DR server (4 virtual ...
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1answer
4k views

HP DL380 G7 + Smart Array P410i + sysbench -> poor raid 10 performance

I have running system with low IO utilization: HP DL380G7 ( 24gb RAM ) Smart Array p410i with 512mb battary backed write cache 6x SAS 10k rpm 146gb drives in RAID10 Debian Squeze linux, ext4 + LVM, ...
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1answer
2k 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 ...
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3answers
2k views

How valuable is TCP Window Scaling?

On a busy† Debian Lenny server of mine I am considering disabling TCP Window Scaling. Why? I'd like to enable syn cookies, which disables TCP Window Scaling. This server is locally firewalled and ...
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5answers
2k views

PostgreSQL High Performance Setup

I am setting up a server with the following specs: * Qty 4 Processors (AMD Opterons with 12 cores each) * 32 GB Memory * Qty 8 HDD (15K SAS Dual Port) * CentOS 5.5 * JBoss * PostgreSQL It is likely ...
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4answers
2k views

SSD drives and RAID configurations vs LVM

Background: I'm familiar with the basic RAID levels, and am curious to know if using SSD devices in a RAID0 or RAID5 would be a better deployment than adding them to a large LVM volume. ...
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2answers
468 views

Very active database with high % disk times

I have a very active website which is using a NoSql database (RavenDb). I don't have exact figures as i'm not quite sure how to extract this information (any help would be great!) But looking in ...
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6answers
1k views

Need help diagnosing network performance issues

I am currently working in a developing country as a system analyst for a government department. My area of expertise is software projects, but I've come across a few issues with the network setup in ...
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3answers
1k views

Certain SQL queries performing very poorly in ESXI hosted environment

We recently set up a new machine with 8 dual-core CPUs, 20 GB RAM, and 3 1-TB drives set up in a RAID of some sort resulting in 2 1-TB drives we actually get to use (I'm not the hardware guy here). ...
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5answers
6k views

Improving VPN performance - stronger encryption = more performance?

I have a site-to-site VPN set up with two SonicWall's (a TZ170 and a Pro1260). It was suggested to me that turning off encryption (so the VPN is tunneling only) would improve performance. (I'm not ...
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3answers
8k views

Configuring Varnish to rewrite Expires/Cache-Control headers for client-side caching

How do I configure Varnish so that all responses to requests matching say "*.css" gets cached in the client's browser for 30 days? What I'm trying to achieve is making Varnish set the correct ...
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2answers
2k 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: ...
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3answers
23k views

How to set shmall, shmmax, shmni, etc … in general and for postgresql

I've used the documentation from PostgreSQL to set it for example this config: >>> cat /proc/meminfo MemTotal: 16345480 kB MemFree: 1770128 kB Buffers: 382184 kB ...
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3answers
192 views

How to compare CPUs?

What are the metrics and their priorities to compare task specific performance of various CPUs?
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6answers
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 ...
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1answer
1k views

Linux Read-Ahead Downsides

Hope all is well. I have a question regarding read-ahead caching. Are there any downsides to raising the size of the read-ahead cache? On our farm, we're currently running at 256, and upon raising ...
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4answers
2k views

iptables, blocking large numbers of IP Addresses

I'm looking to block IP addresses in a relatively automated fashion if they look to be 'screen scraping' content from websites that we host. In the past this was achieved by some ingenious perl ...
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5answers
10k views

Would the database compatibility level affect performance?

We just migrated our Microsoft SQL Server from 2005 enterprise to 2008 standard on the same specification hardware. The databases were backed up and then restored to a clean sql 2008 install. The ...
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2answers
822 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 ...
5
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1answer
3k views

Win 2008 R2 - copying TO disk is very slow, copying FROM is more or less okay

I have Windows 2008 R2 SP1 with 4 identical SATA disks (Seagate Barracude 7200) in RAID 5 array. It has 4Gb of memory; all recent updates are installed. Problem: when I copy large file from one ...
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3answers
292 views

Speed test between clients and server

I want to test each downstream of several clients (~100) which are connected to a media server. They are continuously downloading media files and I want to check which clients have a slow internet ...
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1answer
6k views

How is memcache distributed?

I've got memcache running on 5 web servers all of which are on the host list in php and which are load balanced on the front end. So since memcached is supposed to be distributed the php client will ...
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3answers
227 views

SQL Server Express

If I have 50k hits per day on a site using SQL Server express, is that an issue? How easy is it to schedule backup and other tasks? I know it's all doable, but is it more of a pain? EDIT: I ...
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1answer
1k views

Does APC really improve performance with PHP 5.3+

According to a Linux Adminstrator over at Hostgator: With PHP 5.3 having APC installed is not needed as PHP 5.3 already has improvements that APC does resolve in it. Is that statement actually ...
5
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3answers
2k 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 ...
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1answer
432 views

AMD 24 core server memory bandwidth

I need some help to determine whether the memory bandwidth I'm seeing under Linux on my server is normal or not. Here's the server spec: HP ProLiant DL165 G7 2x AMD Opteron 6164 HE 12-Core 40 GB RAM ...
5
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2answers
804 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, ...