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Questions tagged [performance]

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

3
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3answers
1k views

Seeking inside file performance under BTRFS with LZO compression

I am planning to use btrfs on a 50 TB RAID6 array and I want to enable lzo compression. This is for bioinformatics setup where lots of seeking within large (1 TB -- 20 TB) files occur. (The software ...
-1
votes
0answers
13 views

How to mitigate backend stress generated from malicious traffic

I want to reduce, or mitigate the effects of, malicious layer 7 traffic (targeted attacks, generic evil automated crawling) which reaches my backend making it very slow and even unavailable. This ...
0
votes
1answer
1k views

Load testing nginx inside AWS

I'm trying to load test nginx running on AWS. I need to try to optimise it to handle 1Gbps of inbound traffic. Currently I've got it to peak at 85Mbit/s by running nginx on an m1.large with 4 other ...
0
votes
1answer
2k views

Optimum size for ISA server disk cache

Our ISA server administrator is saying this: How the ISA cache works is as follows: when the ISA server receives a request to access a website, the first step it takes is check through the ...
0
votes
1answer
149 views

Which is faster, key_cache or OS cache?

In a tb with 1 mil. rows if I do (after I restart the computer - so nothing it's cached): 1. SELECT price,city,state FROM tb1 WHERE zipId=13458; the result is 23rows in 0.270s after I run 'LOAD ...
1
vote
1answer
2k views

PostgreSQL: performance descrease due to index bloatper

I'm running a PgSQL 8.1 on a CentOS 4.4 system (not upgradable unfortunately). There's a Java app running on top of the PgSQL daemon and we got to reindex the database every 2 months or so. Also ...
0
votes
2answers
375 views

Sphinx indexer slows down the database: How to give it low priority?

All my tables use InnoDB, and I have set sphinx sql_range_step to the minimum, which is 128. This improved the performance a lot, but it is still very slow if you make a request right after a new step ...
4
votes
2answers
4k views

Why is dropping an index on MyISAM table so slow?

Why is dropping an index on MyISAM table so slow? I can't imagine I'd have social network with 700m records & dropping index. There are only one-column indexes, all of them are fulltext (I need ...
2
votes
4answers
6k views

How to reduce mysql disk io?

mysql> explain SELECT * -> FROM (`items`) -> WHERE `states` = 'A' -> ORDER BY `updated_date` desc -> LIMIT 20520, 40; +----+-------------+--------+--------+--------------...
3
votes
1answer
1k views

Why won't SQL Server use an index seek when running a parameterized query?

When I execute the following query in SQL Server 2005 it uses an index seek, as verified by viewing the execution plan. SELECT * FROM Account WHERE Number = '123456789' But when I run the same ...
1
vote
1answer
1k views

MongoDB high CPU usage

Running MongoDB 2.4.11 on Ubuntu 14.04.1 LTS In top, this mongod thread is constantly using ~195% CPU: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 24524 mongodb 20 ...
-1
votes
0answers
17 views

Mysql high ram usage [closed]

I try to optimization Mysql. There is no problem, but high ram usage. Plesk panel shows high ram usage warning. Where am I making a mistake? Do you have any suggestions about optimization? For both ...
0
votes
2answers
29 views

Performance of Dedicated vs Virtual Server

I have an application that's running in both dedicated and virtual server environments (all Windows Server 2008 R2). Given nearly identical specifications of the servers (memory, processors), the ...
0
votes
0answers
18 views

Streaming proxied responses with gzip on nginx

I have an nginx reverse proxy in front of a node.js backend server. In my node app, I am able to stream responses as they become ready, so that the client can start downloading resources referenced in ...
1
vote
2answers
482 views

Serving a static website with nginx. Response time over 600 milliseconds. What’s wrong?

I serve a wordpress blog with nginx http cached to over 99% of the requests with a cache lifetime of 2 days. Here’s a webpage from the site. The webpages have quite a few images and therefore lazy ...
0
votes
1answer
2k views

How can I determine Breaking point of my Web application using JMeter?

How can I determine Breaking point of my Web application using JMeter? I have executed the JMeter Testplan with different concurrent users load. EX. 300 users(0% error), 400 users(7% error in a sample,...
3
votes
8answers
13k views

Copying large file to remote server causes it to run out of physical memory

I have a strange issue that appears to have started recently. When I copy a large file (Approx 6GB) from my laptop to one of our older fileservers the server runs out of memory after a few seconds. ...
1
vote
1answer
36 views

Bandwidth and IO issues when running hardware raid and zfs

I've inherited a setup using Linux Ubuntu 14, a megaraid_sas, and ZFS. We're getting some performance problems (never being able to fully utilize the 6GB bandwidth from the raid) and I'm curious if ...
25
votes
6answers
54k views

Incredibly low KVM disk performance (qcow2 disk files + virtio)

I'm having some serious disk performance problems while setting up a KVM guest. Using a simple dd test, the partition on the host that the qcow2 images reside on (a mirrored RAID array) writes at ...
-3
votes
1answer
30 views

MYSQL just using 1GB [closed]

My System just uses 1GB of Ram but i get a lot of nginx 504 Errors and i guess mysql is the bottleneck any hints welcome htop output
0
votes
2answers
15k views

How can I test the read speed of a RAID1 device?

Some RAID controllers speed-up read access when using RAID1. Other controllers can't do that. Trying some RAID1 configurations, I want to know if the read speed is faster both on a single file and on ...
26
votes
5answers
54k views

How to identify I/O bottlenecks on a Linux server?

How do you determine that the performance of your Linux server is I/O bound and, perhaps more importantly, what process or processes are casuing the problem?
0
votes
1answer
118 views

Poor network performance on host machine using libvirtd / Qemu / KVM

We've got two Fedora 27 servers that we use to host several virtual servers using libvirtd / Qemu / KVM that are experiencing the same issue. When freshly booted, network performance is great, pings ...
0
votes
1answer
41 views

Linux Ubuntu disk usage

Currently, I have a streaming dedicated server, below you will be able to see server details: HDD: 12TB HDD RAM: 64GB Processor: Intel® Core™ i7-6700 Quad-Core Skylake Hyper-Threading Network speed: ...
3
votes
2answers
49 views

Linux VM too slow (vmware) with a lot of resources available

I got a problem with my VM and I ran out of imagination on what can be causing it. My VM is Red Hat Enterprise Linux Server release 6.9 (Santiago) Kernel: 2.6.32-696.30.1.el6.x86_64 These are my ...
0
votes
1answer
48 views

How does sar collect/calculate disk utilization %?

I'm pretty sure sar's disk utilization % shows how much of the disk is being utilized at any given time, but how does it calculate that? I found: %util Percentage of CPU time during which I/O ...
28
votes
4answers
45k 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 ...
2
votes
1answer
4k 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
votes
1answer
13 views

Hyper-V Mixed SQL server

I'm looking to setup a new SQL server. This is obviously a rather large expense so I was hoping to offset some of the cost by visualizing the machine and putting some other tasks on that same piece of ...
26
votes
1answer
1k views

Unexpected and unexplained slow (and unusual) memory performance with Xeon Skylake SMP

We've been testing a server using 2x Xeon Gold 6154 CPUs with a Supermicro X11DPH-I motherboard, and 96GB RAM, and found some very strange performance issues surrounding memory when compared to ...
4
votes
7answers
5k views

How to tell if linux disk IO is causing excessive (> 1 second) application stalls

I have a Java application performing a large volume (hundreds of MB) of continuous output (streaming plain text) to about a dozen files a ext3 SAN filesystem. Occasionally, this application pauses for ...
0
votes
0answers
437 views

Google Cloud Long TTFB

Google Cloud seems to be having much longer TTFB than they specify in their documentation for cloud storage. You can see from this WPT result that it varies from 500 to 700 MS. The documentation here ...
0
votes
0answers
569 views

What can be done increase bandwidth from Citrix XEN guest to Citrix XEN guest on the same physical host?

Guest VM to guest VM bandwidth on a single Citrix 7.6 XenServer host caps out at about .6Gbits/s using UDP and 6Gbits/sec using TCP. UDP performance over restricted shared memory does not reach ...
38
votes
6answers
40k views

Process runs slower as a scheduled task than it does interactively

I have a scheduled task which is very CPU- and IO-intensive, and takes about four hours to run (building source code, if you're curious). The task is a Powershell script which spawns various sub-...
7
votes
1answer
4k views

iotop and iostat disagree

I'm trying to understand what's going on with my server's disks. It's running Ubuntu 12.04LTS and I'm used to using iostat to know when the disk is the bottleneck. But iostat -xd looks to me like ...
0
votes
0answers
19 views

Rsync: High write load in swift but no writing

I have following problem. After replacing a broken HDD in my OpenStack/Swift node i have an issue. After putting in the new HDD and (re-)starting all of the needed services OpenStack/Swift starts the ...
13
votes
2answers
675 views

Performance impact of running different filesystems on a single Linux server

The book "HBase: The definitive guide" states that Installing different filesystems on a single server is not recommended. This can have adverse effects on performance as the kernel may have to ...
9
votes
3answers
71k views

HDD: performance differences between 7.2k SATA and 15k SAS

What is the rule of thumb in performance characteristics and differences between 7200rpm (SATA/SAS) and 15000rpm (SAS) hard disc drives of the same generation?
0
votes
1answer
929 views

Server 2003 slow share

I am running an 03 box with shares active. When uploading to the share, the speed is average. About 15-20 mbps.. This server is connected directly to 2 other machines accessing the server. When ...
3
votes
1answer
63k views

Mysql showing 100% CPU usage [closed]

I'm experiencing some problems with my MYSQL server installed with Cpanel. My server is showing 100% usage of mysql even if I don't have too much traffic on web. I am running CentOS 6.5x64 with 80GB ...
0
votes
0answers
41 views

apache basic auth slowing performance

I've got a web application running on CentOS 7.6, apache 2.4.6. The website is experiencing significant lag in loading pages, up to 4 or 8 seconds. This is before my php scripts are even called to run....
1
vote
0answers
82 views

Proxmox bridged TAP-to-TAP virtio performance slow

so a little info about my setup: Running Proxmox 5.3-11 with latest updates Running 2 Windows 2012 guests (we'll call them winhost1 and winhost2) with virtio NICs and latest spice-guest-tools (with ...
1
vote
1answer
1k views

Randomly slow MySQL queries

I know this type of question come often. But I have done a lot of research, tried a lot of different settings, but still have the same issue: queries that usually are very fast can take 3s to 5s ...
5
votes
1answer
954 views

Ext4 cache options on a virtual machine

I'm trying to speed up a standup of virtual machines used for development / automated test environments and wanted to verify some assumptions about disk writes caching. I'm using ext4 for the root ...
0
votes
0answers
24 views

Alternative for Performance and Reliability Monitor

Do you have alternative for Performance and Reliability Monitor? I would really loved to get RAM Use, Disk Read/Write, Processor and Network graphs to be shown in one environment/page, with custom ...
6
votes
0answers
93 views

What could cause a LAMP server to perform poorer than my laptop?

I'm running a WEB application (PHP + MariaDB) for my company, developing on my laptop and running the production version on a dedicated server. Recently, I've started to measure performance and ...
0
votes
1answer
982 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 ...
0
votes
1answer
987 views

poor performance with vmdk mounted as loop device even after conversion to raw

Edit 13/12/12 - At this stage it would appear to be related to Western Digital (and possibly others) Advanced Format 4K block sizes. This link goes some way into describing the issue, however the ...
0
votes
1answer
30 views

Cassandra long queries (33s for dropping empty table)

Currently trying a setup for a large project. The project will utilize tens of thousands of tables to chunk the big data into separate pieces that are faster to search. So to test this I'm creating ...
0
votes
1answer
25 views

`find /nfs/server/mount/data[12] -name data_*.gz > /dev/null` 4x slower the second time it's executed - why?

An NFS server (it's some sort of NAS appliance, I do not know what brand, nor anything about how it is configured) has a single filesystem exported and mounted on a Linux client. Server and client ...