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2
votes
3answers
615 views

IOs reads writes per file

My target is to equally separate mysql database across the number of drives, using symbolic links on tables. Now I can not seem to find the way to check IOs, reads, writes per table on mysql. So now ...
0
votes
1answer
238 views

configuration for max read throughput on ssd: pcie vs sata vs raid

I'm looking to configure a storage setup, using ssd's, that will deliver the fastest read throughput on large (2+ GB) files on a 24 core (12 physical core) system. The data is static for the most ...
4
votes
2answers
752 views

Why does a CP command on linux consume CPU?

I just run a copy command for two large directories with a small number of huge files and I see my cp process is consuming around half a core in top: 51116 root 20 0 110m 876 688 D 43.9 ...
0
votes
3answers
779 views

Resource monitor and how to spot if you have disk I/O problems?

I have an application server which runs pervasive SQL and app using it. Last weeks the users are complaining about poor performace of the app and I suspect disk I/O problems because CPU and RAM ...
0
votes
2answers
153 views

wait rate very high due to mysql server activity

Sometimes the server is very slow and needs a lot of time for serving the requests. iotop shows a disk read rate of 1-2 M/S on average for some minutes (which is not that much actually), after that ...
3
votes
2answers
4k views

Is there a way to delete 100GB file on Linux without thrashing IO / load?

I have a huge log file I need to delete on a production web server. I'm worried it'll bring the system to a crawl if I rm it on Linux. Any brilliant ideas? Update: Filesystem: ext3 Partition: /var ...
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 ...
3
votes
2answers
1k views

Is a 'high' IO rate healthy?

I do a lot of work with my Linode that currently hosts a site, but every now and then (usually once every two months or so) - I'll get a warning about my IO rate being too high (Usually just higher ...
0
votes
4answers
3k views

Reducing IO caused by nginx

I have a lot of free RAM but my IO is always 100 %util or very close. What ways can I reduce IO by using more RAM? My iotop shows nginx worker processes with the highest io rate. This is a file server ...
0
votes
1answer
183 views

Delay before download starts when serving files using nginx

I am currently using nginx to serve downloads off my website. Users sometimes need to wait about 5 seconds before their download starts after clicking a download link. I'm not sure if I need to start ...
1
vote
2answers
844 views

Try to delete files used by IIS

I got a service coded in c# whoes deleted somes web site files hosted on iis, before an update. But sometime when i delete the files, they stay there. If I try to delete them manually, via explorer, ...
0
votes
3answers
761 views

DB Server Disk I/O utilization

I have a Linux server that I use to run the DB of my application (MySql), the server have 8GB Ram and 4 cores. there are no other applications running on the server besides the MySql. Most of the ...
5
votes
1answer
992 views

5.5GB written daily to 1.2GB root volume - 4 times previous levels

Problem: I recently revamped one of my servers, it was tested prior to use, and functions well, however, a few days ago, I noticed approximately 4 times the usual amount of writes to the root volume. ...
2
votes
2answers
2k views

High disk I/O activity in CentOS server

I have about 16 websites in a CentOS dedicated, and I am having some problems on high traffic hours, it seems to be a high disk I/O activity causing a general slowdown. I've installed atop and this ...
1
vote
1answer
622 views

How to track a single Xen VM's I/O utilization

What is a good way to monitor I/O individually for Xen Virtual Machines (not Dom0)?
0
votes
1answer
691 views

IO utilization percent of 4920.45% - iostat -x , What's wrong?

I have seen wrong percent use of a disk IO some times on servers that have been a long time without reboot. By any means this server has significant IO. Tonight it'll be rebooted and I'm sure ...
1
vote
2answers
165 views

How to analyze system calls when your disk is in read only and strace output is “Bus error”?

We have a HW problem with the disks, that made all the mount points to be read only. Output of dmesg: end_request: I/O error, dev sda, sector 15574609 sd 0:0:0:0: SCSI error: return code = 0x00040000 ...
4
votes
3answers
4k views

Utility for Monitoring IOPS on servers

We recently ran the Dell Performance Analysis Collection kit which monitors your servers via WMI for 24 hours. You send the file off to Dell and they return a report with graphs of IOPS and MB/S disk ...
4
votes
2answers
213 views

/etc/passwd continually accessed

I'm running a server on EC2 (Cent OS, 2.6.35.14, x86_64), and I recently went over my 1 million I/Os per month quota, which is absurd, as my disk utilization shouldn't be anywhere near that. (I'm not ...
1
vote
1answer
230 views

Good SAN sequential I/O throughput

We have an EMC San - CX4-240C filled with 15k (4Gb) Fibre Channel disks setup in RAID 5. Our applications that run on this SAN do primarily Sequential read and write of large text data files. I'm ...
0
votes
2answers
155 views

Possible disk IO problem. Help to be sure.

Since some time days ago, one of my servers started crashing. Currently it is crashing almost every day. Sometimes, over once a day. Only a restart can solve. The last time the problem happend, the ...
10
votes
2answers
1k views

How does Linux handle concurrent disk IO?

When a Linux server is serving many concurrent requests to read many different files, does it: Seek to File_1, read the entire file, then seek to File_2, read the entire file, then seek to File_3, ...
5
votes
1answer
556 views

Maximizing throughput of virtual file systems

I've been using a QEMU system to build software. The problem I've been having is that the system seems to suffer from extremely slow disk access. This is not necessarily a problem as it's not really a ...
1
vote
1answer
209 views

Does DFS-R actually write 100%+change to a file on the receiving server(s)?

I am analyzing DFS-R on Windows 2003 R2 and have come across a horrendous thing. It appears that when you append a small amount of data to a large (existing) file, the write cost on the server for ...
3
votes
1answer
1k views

Monitorig ZFS io with Zabbix [closed]

I need to monitor per-zpool IO stats (number of reads, number of writes, size of reads, size of writes) with Zabbix. Is there a script for that? kstat provides only agregate data (all zpools summed ...
1
vote
1answer
809 views

iotop for Linux kernel 2.6.18

So it has to come to my attention that iotop isn't availalbe for 2.6.18 since it's less than 2.6.20 and requires Python 2.6+. I've done some research and came across this article: ...
0
votes
1answer
252 views

IO Speed virtual image vs Physical?

I am planning on building a Continuous Integration Server (the existing one is too slow). My plan is to run multiple OSes for our application testing on KVM. The structure will be a single physical ...
1
vote
1answer
6k views

kernel: scsi 0:0:0:0: rejecting I/O to dead device

Yesterday, OSSEC sent me an alerting email: Jul 29 21:25:16 SVR4149 kernel: end_request: I/O error, dev sda, sector 334634969 Jul 29 21:25:16 SVR4149 kernel: sd 0:0:0:0: SCSI error: return code = ...
2
votes
1answer
222 views

inonice not working properly in xen dom0

I have a Xen Dom0 (3.2) with a bunch of domUs (paravirt). DomU VBDs are on local LVM volumes. Now I want to get backups of the LVM volumes using snapshots. I use rsync ioniced to idle (ionice -c3). I ...
1
vote
1answer
531 views

IO and bus errors on Ubuntu Server

I've got an old computer running Ubuntu Server 10.04, which acts as router, file server and web server. A couple of weeks ago I inserted a PCIe video card, since the motherboard did not have any video ...
3
votes
2answers
1k views

In Windows Task Manager, in the Processes tab, what does I/O Other mean?

In Windows Server 2003, I'm seeing a process in Task Manager with a high value in the I/O Other column. I'm trying to determine if it's in some kind of error state, but I don't know what I/O Other ...
7
votes
1answer
865 views

using temporary files vs pipes advantages and disadvantages

say I have a file named jobs.csv and I would like to get the top 50k jobs done by Foo I can either do: # cat jobs.csv | sort -u | head -n 50000 > /tmp/jobs.csv # cat /tmp/jobs.csv | while read ...
11
votes
2answers
1k views

How do you monitor the performance of a character device (e.g. tape drive)?

There are many ways to monitor block device performance: dstat and iostat, heck, even sar will give you data on block device I/O rates. Unfortunately, I don't know of any good spur-of-the-moment ...
2
votes
2answers
2k views

Monitor Disk I/O Using DD

I've bee looking into the possibility that my server is experiencing a lot of iowait issues. I've found a lot online about running the dd command. I am unable to run this conv: [root@vps ~]# dd ...
2
votes
1answer
3k views

On Solaris, how can I tell what processes are doing disk i/o on a particular device?

On Solaris, iostat tells me that a device is 92% busy, but how do I find out what programs are making the requests?
6
votes
2answers
1k views

How to set i/o priority for nfs client processes?

The configuration is: A linux server and a nas box (netgear) acting as nfs server. It is easy for a single process on the linux server to use all i/o bandwidth by simply copying a file from the nfs ...
0
votes
1answer
928 views

What do the output values of dstat command mean when monitoring IO?

I am monitoring the IO and SWAP usage of a process in my backup server. I executed dstat -rs 5 and this was an example output: --io/total- ----swap--- read writ| used free 92.0 57.3 |3228k 514M ...
1
vote
1answer
496 views

Ramdisk vs Build-In IO Caching on Windows

I'm trying to understand the built-in IO cache on Windows. If an application writes to a file, and then reads/writes it multiple subsequent times, it seems that the IO cache should allow this to ...
0
votes
4answers
608 views

How can I get a list of Programs doing Disk IO?

I have a server (running CentOS 5) and I need to figure out which programs (MySQL, Apache, etc) are doing the most Disk I/O? Is there a command that will allow me to calculate an average over time?
2
votes
2answers
335 views

comparing disk performance of machines

I am in the process of moving applications running on old Linux machines onto VMs. As part of this, I need to justify the VMs have at least the capacity (i.e. CPU speed, RAM, disk, disk speed, network ...
4
votes
4answers
17k views

How to measure IOwait per device?

I have a server, which exports home directories over NFS. They are on software RAID1 (/dev/sdb and /dev/sdc) and the OS is on /dev/sda. I noticed that my %iowait as reported by top and sar are ...
1
vote
3answers
1k views

Dell PE2950 - slow IO rates for writing and reading locally

I'm having a serious issue with dell server PE2950. The server has really slow IO rates, so slow that I'm not able to use it anymore I tried few things to solve this: changing disks to new disks ...
1
vote
3answers
174 views

Benchmarking a hard disk drive for OLTP

I have a PostgreSQL database (OLTP, 10GB in size) server and I'm planning an array of hdds for it's storage. I have various disks I can use. I need to find the best ones for the job with the right ...
1
vote
4answers
1k views

NFS IO priority on ZFS/Solaris

I've got a Nexenta/ZFS NAS that I'm using as an NFS backing store for a small VMware vSphere farm. At the moment I have 9x1TB disks all mirrored (last disk is configured as a write log device). The ...
3
votes
1answer
606 views

Measuring Disk IO programmatically

I want to measure some numbers related to disk io in a given timespan, programmatically. This means I don't want to spawn a process like iostat to get my numbers, by prefer to read something from proc ...
1
vote
5answers
508 views

Scratch files in /tmp getting mysteriously deleted

I have certain files in a /tmp subdirectory that a script I wrote uses for scratch. The opens and closes these file perfectly fine for a few hours. Then, out of nowhere, the files are no longer found. ...
63
votes
13answers
13k views

Are networks now faster than disks?

This is a software design question I used to work on the following rule for speed cache memory > memory > disk > network With each step being 5-10 times the previous step (e.g. cache ...
2
votes
4answers
9k views

Determine what's causing high disk IO

I'm having a problem with my VPS and disk IO. My server is running nginx + PHP-FPM + APC. The database is located on another dedicated VPS. I have several Wordpress MU sites living on the web server. ...
1
vote
2answers
964 views

High Disk I/O rate. How to investigate

One of my servers is getting very high Disk I/Os. The problem is that the disk I/Os are constantly increasing. The server just have simple LAMP configuration and there shouldnt be any disk operation ...
12
votes
4answers
4k views

Measuring 'total bytes written' under Linux

We're quite interested in exploring the possibility of using SSD drives in a server environment. However, one thing that we need to establish is expected drive longevity. According to this article ...