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

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33
votes
5answers
27k views

Which PHP (opcode) cache one should use and why?

I keep hearing about some PHP (opcode) caches like - APC, XCache, Memcache, eAccelerator, etc. But I couldn't ever figure out how to go about choosing one. Apart from performance benefit, which a ...
5
votes
1answer
3k 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 ...
-4
votes
0answers
12 views

Hard Disk read/write latency calculations in linux

How do i calculate Disk read and write latency in Linux? Is it possible to do the calculation using /proc or /sys file system? else is it possible to get through iostat command ?. screenshot here
-1
votes
1answer
27 views

Handling the potential risk of writing random bits to storage during power loss with RAID

Is it possible for a power failure to cause some part of a machine to write one or more random bits to a storage device? Someone proposed the following idea to address such a risk: create multiple ...
1
vote
2answers
1k views

Horrible PHP/MySQL Query Performance On Ubuntu Server 10.04

I just did a clear install of Ubuntu Server 10.04 with the standard LAMP config.. Then I made a small script to test insert speeds into a table with 3 columns. When I run the script on any of my ...
0
votes
0answers
13 views

LSI SAS1068E (aka LSI SAS 3442E-R) bandwidth

Recently I connected LSI SAS 3442E-R and two HP SAS 600GB 10k HDD. My motherboard is AsRock Z97 Extreme6. Disk are configured as JBOD, no raid. Linux lspci shows: 0b:00.0 SCSI storage controller: ...
2
votes
1answer
40 views

CPU is only used 50% on full load on a Windows Server 2012 R2

I use Windows Server 2012 R2 on my home server (it's a mini-ITX PC based on an Asrock E350M1/USB3 motherboard, so it's not a strong enterprise server). My problem is that even when I run multiple ...
3
votes
2answers
83 views

Linux: Why does the CPU frequency fluctuate when using the performance governor?

I'm using a Debian 8 amd64 machine for benchmarking. During experimentation, I would like the CPU to operate at a fixed frequency (preferably the maximum possible). This will rule out the CPU clock ...
2
votes
1answer
64 views

Nginx performance when running multiple instances on the same machine

I'm trying to understand the performance impact of having multiple nginx instances (masters) running on the same machine, rather than having them all load into a single instance using different server ...
2
votes
3answers
78 views

Apache - drawback to high number of httpd processes always running

Is there any issue with having a high number of spare httpd processes always running? I ran a test where I increased StartServers and MinSpareServers by 1,000 and measured the increase in memory ...
2
votes
2answers
31 views

Can idle NFS mounts on several clients impact performance

We had a NFS server at work which was working with slight lag. However as more mount points were getting created at several clients(serviced by the same server) we noticed the performance coming to a ...
0
votes
0answers
21 views

The difference in performance of different memory mount in dell poweredge R430

There are 3 servers R430 (S1, S2, S3). All of them have 2 procesors and 8*8GB of ram in slots A1-A4 and B1-B4. There is a need of extending memory. I've read dell recomendations ...
5
votes
4answers
8k 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, ...
-2
votes
3answers
55 views

how to detect remote switch speed and duplex? [on hold]

We have a linux (RHEL) system which will be deployed in unknown networks. To support old networks we want to have autoneg configurable. how do you how detect if remote switch is autoneg on|off, and ...
0
votes
1answer
26 views

Is it bad to use swap with SSD when running a server out of memory?

I have DigitalOcean VPS, which has 2GB of memory. I'm soon running or am about to run out of it. How big is the performance hit if I use big swap? DO use SSD has harddrives, and I'm not the one who ...
1
vote
1answer
41 views

Slow file io performance after large network copy on Win7

In a step of our build process we run a tool that generates about 125,000 files. When generation is complete we copy them up to a network share so other systems can copy them down to process further. ...
0
votes
2answers
1k views

Troubleshooting MySQL Performance Issues

Environment: 1 physical machine 8GB RAM some older Core2Duo CPU 1 HDD Windows Vista 64 bit 1 Virtual Machine 16 GB RAM 2 vCPUs Windows 7 64bit Both machines running MySQL 5.5.28 (64Bit) with ...
1
vote
0answers
33 views

Redis parent process smashing disk despite appendfsync = no

We are seeing loads of IO from redis-server despite our save operations being set to occur once every 15 minutes only. The workload is a "full page cache"; we store blobs of compressed HTML. The HTML ...
3
votes
4answers
544 views

Azure IO performance

We have a number of Windows Server virtual machines that we use for .NET and Java development and QA. I find Azure attractive for the obvious reasons but mainly for the opportunity to reduce ...
1
vote
2answers
118 views

ZFS reads on FreeBSD incredibly slow

I have a FreeBSD 10.0 system on which I have MySQL running with its InnoDB database files stored on ZFS. It seemed to have been going fine for months, but lately, and seemingly suddenly, performance ...
4
votes
1answer
949 views

BackupExec 12 + RALUS - VERY slow backups

We use Backup Exec 12 and the Remote Agent for Linux/Unix Servers (RALUS) to backup a large RHEL5 system. For various reasons we need to do a daily working set job. These working-set jobs run ...
1
vote
1answer
30 views

Debugging slow server response time [closed]

I'm testing response time of my VPS server: curl -s -w %{time_total}\\n -o /dev/null http://www.example.com The values are typically round 300ms, Google suggests that it should be lower than 200. ...
0
votes
2answers
865 views

Optimizing disk performance on KVM VM configuration

I have a KVM host server running Ubuntu 12.04 LTS, bare bones installation with only KVM installed. The server has an 8 Core Intel(R) Xeon(R) CPU E3-1230 V2 @ 3.30GHz CPU with 32GB of RAM and SATA ...
4
votes
0answers
21 views

HP MSA P2000 G3 Disk Scrubbing performance?

I have a HP P2000 G3 array with two 10Gbit iSCSI controllers in it that presents storage to my virtualisation cluster. It is soon to be expanded with two D2700 shelves each loaded with 25 10k RPM ...
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 ...
0
votes
0answers
31 views

apache 2.2 to 2.4 sporadic performance drop

I updated apache from 2.2 to 2.4 and php from 5.3 to 5.4. For some reason I am experiencing huge performance drops in around 5% of requests to the server. On average, sites load in less than 2 seconds ...
3
votes
3answers
2k views

How can I check if my DB needs more RAM?

How would you check if your postgresql DB instance needs more RAM memory to handle their current working data?
0
votes
0answers
14 views

Conservative Azure Windows VM to Run SQL Server 2008 R2 [duplicate]

For testing purposes I need to set up three Azure Windows VMs to each run an instance of SQL Server 2008 R2 each holding one DB of approx 100GB. There will be quite a few complex stored ...
0
votes
0answers
16 views

Performance monitors

I would need to create a performance monitor on windows server 2012 R2 to monitor the following for a particular period(may be one hour) CPU usage Memory usage Network bandwidth I'm little ...
14
votes
3answers
624 views

NFS poor write performance

I have two machines connected with 10Gbit Ethernet. Let one of them be NFS server and another will be NFs client. Testing network speed over TCP with iperf shows ~9.8 Gbit/s throughput in both ...
0
votes
0answers
20 views

Sudden increase in my CPU usage during random moments(Win Server 2012)

At random times, no matter if I am online or not I see that my server having increased Process usage spikes, as you can see in the picture: So I go inside the Dashboard on the Server Manager, look ...
3
votes
1answer
1k views

Very poor disk performance on KVM node - mdadm raid10

For a long period of time, i'm experiencing performance issues on CentOS servers that are used for KVM virtualization. I'm running software RAID-10 with 4 disks (Seagate ST2000DM001, 2TB, 7200rpm ...
1
vote
1answer
1k views

Unexplicable extreme slowness on Dell PowerEdge R320, fixed only by cold reboot

At this customer's site, there are two new Dell PowerEdge R320 servers with the following configuration: A single 6-core CPU 16 GB of RAM 2x500 GB SATA disks in a RAID 1 array The O.S. is Windows ...
4
votes
1answer
7k views

MySQL high CPU usage on small website

I have a small website hosted on a dedicated server (FreeBSD 9.2, MySQL 5.6.1 and php 5.5.5). The problem is that MySQL eats a lot of cpu resources even if the website have a few visitors. The ...
1
vote
1answer
1k views

interpreting IOPS these Bonnie++ and iostat results

I am looking to interpret the IOPS from a few runs of bonnie++ using iostat simultaneously and using the benchmarking from this post: Can I determine IOPS on a disk array using bonnie++? bonnie++ ...
-1
votes
1answer
24 views

Is there a way to determine what impact an upgrade will make other than benchmarking it myself? [closed]

Several posts on capacity planning tells me that the only way for me to determine what hardware I need is to test it myself and benchmark it. Benchmark your code on hardware similar to what you'll ...
1
vote
0answers
35 views

VMWare ESXi and iSCSI via FreeNAS

I've recently been setting up a sandbox ESXi environment with a VM running FreeNAS providing a volume which is connected as a datastore on the host via iSCSI. I've created a VM on this datastore and ...
1
vote
1answer
35 views

RAID1 write penalty using mdadm - what's the cause?

When doing some performance tests writing to a SSD-based 3-way RAID 1 mirror powered by mdadm, it appears we suffer a significant write penalty of about 2.2x slower than doing the same test on just ...
17
votes
4answers
10k views

Why VM snapshots are affecting performance?

I read in one of the VMware KB articles that snapshots will directly affect VM performance. But my team keeps asking me how snapshots can affect performance. I would like to give them solid reason ...
0
votes
1answer
2k 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 ...
5
votes
2answers
364 views

iozone: 5 concurrent threads random read of 300K blocks does more ops/s than using only one thread, what could be the underlying reason?

The partition is in RAID1 using software RAID. Command line used: iozone -s 190g -r 300k -O -b test_file OPS Mode. Output is in operations per second. ...
1
vote
2answers
495 views

Can one root server handle over 50M requests per month? [duplicate]

I am running a LAMP Application installed on one server, happily serving about 1M PI per month. Now I am looking into a potential partnership where my app might serve around 50-80M requests per month. ...
3
votes
2answers
106 views

Performance azure disks, high average queue length

I'm having a classic developer-system admin battle where I am stating that there is an IO problem on the disk of the shared sql server while the system admin tells me that the capacity hasn't been ...
1
vote
0answers
98 views

100% CPU, load average 0 - how is this possible?

Here's the top output: top - 19:20:47 up 1 day, 4:30, 1 user, load average: 0.01, 0.07, 0.12 Tasks: 170 total, 1 running, 169 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.6 us, 0.9 sy, 0.0 ...
3
votes
1answer
1k views

How to achieve multiple NFS/TCP connections to the same server?

I'm trying to maximize the NFS/TCP bandwidth between a Linux client and a single NFS server over a 10Gbps link. Although each NFS mount has its own device (major/minor), everything comes down to a ...
3
votes
4answers
1k views

How to troubleshoot performance issues of PHP, MySQL and generic I/O

I have a WordPress based website running on a shared hosting. Its response time is very decent (around 2s to retrieve the HTML page and 5s to load all the resources). I was planning to move it to a ...
3
votes
1answer
1k views

CentOS Tuned Equivalent For Debian

Running a few systems, a few are Debian which have been great. I have on the CentOS boxes tuned(tuned-adm) installed and setup for throughput. I searched all over Google and only found some articles ...
20
votes
5answers
5k views

Software vs hardware RAID performance and cache usage

I've been reading a lot on RAID controllers/setups and one thing that comes up a lot is how hardware controllers without cache offer the same performance as software RAID. Is this really the case? I ...
1
vote
0answers
13 views

Force disk cache even if guest uses direct i/o

Have IBM db2 on Rhel on Hyper-V on Windows Server. The *.vhdx file is on CSV. e.g. C:\ClusterStorage\volume1\hyper-v\oktest-lb1\oktest-lb1.vhdx. db2 uses O_DIRECT flag (uncached i/o) for its database ...
1
vote
1answer
37 views

Different network speeds from servers on same subnet

I have a pretty strange issue, I'm looking for advice on how I can debug it. I have two servers (A) and (B) on the same subnet and switch. Server A->B transfers at a full 12MB/s and vice-versa. ...