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1answer
22 views

What is the difference between rMB_nor/s, rMB_dir/s, and rMB_svr/s in iostat?

I'm trying to interpret the results of running the following command iostat -mnhyc It produces the following Filesystem: rMB_nor/s wMB_nor/s rMB_dir/s wMB_dir/s rMB_svr/s ...
1
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1answer
14 views

slow file server with contradictory values for CPU and CPL in atop

I've got a fileserver (centos 6.3) that slowed down suddenly earlier today. The cluster that mounts it could access other NFS mounts without a problem, but the access to this one was VERY slow. ...
-1
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2answers
91 views

iostat reporting low r/s on first line for specific disk, expected r/s on all following lines for that same disk

When copying data from hard disk sdc to sda, I notice that the number of read requests completed per second was unusually low: $ iostat -x 1 1 Linux 3.13.0-32-generic (melancholy) 2014-08-15 ...
0
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1answer
133 views

Get I/O TPS for NFS on Solaris machines

I'm attempting to get IOPS for my Solaris servers. Typically I use tps for this calculation, however: iostat gives TPS but only for local disks. iostat -x gives everything but TPS for ALL disks. sar ...
3
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2answers
2k views

iostat - How does %util affect %idle and %iowait

Looking at iostat, if the system needs to issue a request for io, but has not yet been able to do so due to %util being pegged, would that wait be counted as %idle or %iowait?
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3answers
2k views

MySQL insert cause high disk i/o wait?

Im getting what appears a lot of wait time when performing large inserts in Mysql. Am I correct in assuming I have a disk I/O problem? Yes I am running Mysql on a VM. Innodb_buffer_pool hit rate is ...
-1
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3answers
3k views

iostat shows 100% utilization - what can be done to improve performance?

I have dedicated web server with CentOS. Recently, I get very high server load, probably caused due to IO bottleneck. iostat -mx 3 shows: avg-cpu: %user %nice %system %iowait %steal %idle ...
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4answers
3k views

How can I find which process is causing this IO read (tried iotop already)

I've got a constant 1.4 megabytes/sec of IO read on one server (see iostat output below). What can I do to find which process is the cause ? I already tried iotop and htop, but could not pinpoint the ...
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0answers
46 views

Strange load average behaviour

We have a daemon which collects system data and writes it into database. Sometimes the load average goes very high without apparent reason. Here is sample output. | id | server_id | datetime ...
0
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0answers
101 views

confused by iostat reporting striped mdadm more tps than aggregate volumes

I've got an mdadm striped device (/dev/md0) from /dev/sdm{1..4}. Here is an output of iostat 30 and then mdadm --detail on the mdadm device # iostat 30 Linux 2.6.32-309-ec2 (ip-xx-xx-xx-xx) ...
3
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2answers
5k views

iostat on Solaris with ZFS - why is wait and %w always zero?

We have a busy server, chocking under a high IO load, at least, that's the feeling I have. Output from iostat -xz looks like this: extended device statistics device ...
9
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3answers
14k views

How can I map iostat device names to LVM /dev/mapper/XXX names?

mount shows mount devices like: /dev/mapper/VolGroup01-LogVol00 on /var type ext3 (rw) or /dev/mapper/VolGrp_backups-backups on /mnt/backups type ext3 (rw) but iostat uses dm- notation. like ...
2
votes
2answers
5k views

How to install iostat to Red Hat 5, without internet connection?

Title is pretty clear, I have a server which doesn't have an internet connection. So I can't use yum or anything like that. I want to download necessary files with my PC and upload to server via SSH ...
2
votes
2answers
183 views

Reporting historical system activity in FreeBSD

I'd like to record data about system activity under FreeBSD for future analysis. If I were running a SysV system, I'd just sar and its related utilities, but that doesn't exist in the BSDs. (And ...
2
votes
1answer
1k views

Windows “iowait” CPU utilization reporting

Does Windows account for and report "iowait" in the same manner as Linux? That is, processes enter "uninterruptible sleep" and their time spent is subtracted from "CPU free"? If so, which Perfmon ...
4
votes
3answers
1k views

Linux utility to record IO statistics (random/sequential, block sizes, read/write ratio)

As part of provisioning our new server (see other SF) I'd like to find out the following: ratio of random to sequential reads & writes amount of data read & written at a time (pref in ...
1
vote
1answer
125 views

Strange iostat numbers

I'm experiencing unusual load issue on one of our VM which is on SAN storage. As a general practice I ran iostat on the server got very strange numbers. avg-cpu: %user %nice %system %iowait ...
1
vote
1answer
237 views

iostat to analyze iSCSI mount

Is there a way to analyze the IO wait on a iSCSI mount from the machine on which the iSCSI share is mounted? I understand the local volumes can be analyzed, but, we have one particular directory on ...
1
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0answers
350 views

MySql/RedHat, High I/O Wait … for a few hours… then disappears

I've got a RH server as a VMWare instance logging GPS fixes 24x7. The transaction volume hasn't changed over the months (in fact I am pruning the transaction table more aggressively now) with only ...
1
vote
1answer
564 views

CPU Usage vs load average [duplicate]

I'm running debian iostat -x Linux 2.6.32-5-amd64 (server56856.uk2net.com) 27/04/13 _x86_64_ (4 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 4.59 0.01 ...
0
votes
1answer
306 views

High cancelled_write_bytes, high IO load, concurrent memory-mapping

I have a software for persisting/retrieving data from files (a bit like database, but it's not exactly a database engine). It's not open source and the documentation is sparse, therefore I don't have ...
3
votes
7answers
5k views

How do I tell which processes are writing heavily to disk in CentOS 5?

Our server started getting slow, so I ran iostat on it. iostat -dx 5 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 ...
2
votes
1answer
284 views

high cancelled_write_bytes

On a MySQL server running on AWS EC2 with an EBS volume iostat returns the following avg-cpu: %user %nice %system %iowait %steal %idle 37.67 0.00 5.26 0.75 0.08 56.24 ...
2
votes
1answer
1k views

Is disk dying? Weird numbers on iostat

I have this old P4 box in my house with Ubuntu Server on it I use as a media server. Apart from the IDE boot drive there is a 1TB SATA disk attached with one of those el-cheapo IDE to SATA adapters ...
1
vote
2answers
175 views

Averaging dstat output

I need to average upload and download speed using dstat -n. How can I add all the received and sent datas that appear after dstat -n, so that I can add them and find average upload and download ...
3
votes
1answer
133 views

How to know which row in fstab need to be changed to relatime/noatime?

If I run iostat I saw this: avg-cpu: %user %nice %system %iowait %steal %idle 15.36 0.78 9.66 21.46 0.00 52.74 Device: tps Blk_read/s Blk_wrtn/s Blk_read ...
5
votes
4answers
2k views

Cannot see graphs for IO Service time and IOstat in munin

For some reason data & graphs for IO Service time and IOstat do not show up in munin. All other graphs are fine. Can some one suggest me how to set munin to show the stats and graphs for these. Am ...
2
votes
2answers
149 views

Do we need to perform disk checking periodically on Linux

Do we need to perform periodic disk checking,for bad blocks and bad sectors?. Our servers havent been restarted for last 4 months,also no disk checking have been performed on any disks. Can that can ...
2
votes
2answers
1k views

How iostat figures out to take CPU idle time to consider as %idle or %iowait?

I was going through iostat man page. According to it, %iowait Show the percentage of time that the CPU or CPUs were idle during which the system had an outstanding disk I/O request. %idle ...
0
votes
1answer
82 views

how can I tell if there is a cpu trashing on my linux machine

I want to write a script that will kill my processes when my machine is doing "too much" swapping of process memory from disk to memory. What is the best way to determine that? I saw top has %wa and ...
2
votes
1answer
330 views

RAID iostat showing 0.00 for wait's and %util

I have a EC2 server running ubuntu 11.10 with 6 raid devices, 5 with 8 EBS drives each as part of a RAID 10 setup, the other one with 4 EBS drives as part of a RAID 0 setup. I am finding that even ...
1
vote
2answers
1k views

tracking down what files are causing io activity in iostat

Using iostat -Nkx 1 I can see that I am getting regular IO on a volume group. What I'm trying to do is find a way to link that IO to a file/pipe/whatever to see what process is creating this IO and ...
2
votes
4answers
1k views

very specific iostat output needed in realtime

Is there anyway to get the output of iostat -m and add only the column await from the extended output in realtime? I know this question sounds nutso but I need to be able to get all those column in ...
1
vote
2answers
241 views

Finding throuput of CPU and Hardrive on Solaris

How do I find the throughput of a CPU and the hard disk on an OpenSolaris machine? Using mpstat or iostat? I'm having a hard time identifying the throughput if it is given at all in the commands ...
1
vote
3answers
1k views

No apparent reason for high load average

We have several web servers running on Amazon (ec2) c1.xlarge, over Amazon AMI. The servers are duplicates of each other, running the exact same hardware and software. Each server spec is: 7 GB of ...
2
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3answers
1k views

How to get iostat of a single process

How can I get iostats io throughput of just a process to try know if this process starts burning my HDD. Thanks!
1
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2answers
3k views

What iowait values are ok?

I am trying to find the bottleneck of a server running a fairly busy php/mysql site. My first culprit was io but iostat shows that on average iowait consumes only %3.60 of cpu time. here is the ...
0
votes
1answer
417 views

iostat: See current usage rather than average

I need to log disk statistics (MB/read, MB/write) of block devices. As I understand, iostat shows an average value. This is not exactly what I want when I'm about to monitor a server. Is there a way ...
0
votes
1answer
689 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 ...
0
votes
1answer
150 views

Counting And Summing Disk IOs in Windows

Among other (see a post of mine) I am trying to count and add the number of bytes read/written to a disk during a minute/hour/day/... on windows. According to the Physical Disk Object documentation ...
0
votes
1answer
969 views

iostat -En output formatting

I have a problem extracting the device names on Solaris 8 SPARC when using 'iostat -En' command since the device names are too long. For example : iostat -en output ---- errors --- s/w h/w trn tot ...
0
votes
1answer
639 views

Raid array overloaded with no apparent reason, iostat output not making much sense?

I am looking to an iscsi installation comprised of the raid arrays managed by an HP P400 controller. 2 pairs of drives each mirrored plus 4 drives in a raid 10 configuration, all 7200rpm sas drives. ...
2
votes
2answers
317 views

How do I know if my disks are being hit with too many I/O reads or writes or both?

I know a bit about disk I/O and bottlenecks relating to this especially when relating to databases. How do I really know what the max I/O numbers will be for my disks? What metric might be available ...
0
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1answer
697 views

Nginx causing high load with not many active connections

I have a linux machine 64bit (centos5.5), 2.83GHz Q9550, 6gb ram and a single SATA 500gb drive. From this machine I only serve thumbnails, most around 10kb in size and at this point there are about 7 ...
1
vote
1answer
1k views

iostat how do I set up a logging

Hi there I am pretty newbie in servers, would appreciate your help. How do I set up an iostat logging? as my Disk IO spikes strange at some random time to very high levels. Thanks.
0
votes
1answer
678 views

SNMP monitoring of iostat on a Solaris 10 server?

I'm looking at the System Management Agent resources which gives guidance to the Solaris SNMP tools however after extensive googling I can't find any OID reference list or details on what can be ...
2
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4answers
1k views

high iostat load on linux

atop: DSK | cciss/c0d0 | busy 87% | read 24193e4 | write 4076e4 | KiB/r 26 | KiB/w 77 | MBr/s 7.61 | MBw/s 3.78 | avq 6.07 | avio 2.49 ms | iostat Device: tps ...
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3answers
2k views

Extremely Slow IO with Simple PostgreSQL 8.4.4 Queries on Centos 5.5

The strange and extremely slow IO pattern I'm seeing is this (output of iostat -dxk 1 /dev/xvdb1): Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm ...
0
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2answers
2k views

Windows: record I/O stats (eqivalent to iostat)

Are there any tools on Windows that allow performance statistics to be recorded? Something similar to iostat 10 > iostat.log on Unix? I have 10 Windows VMs that run a whole lot of regression ...
2
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2answers
2k views

What do the columns in you get from iostat mean?

When I perform the command iostat -x | grep -P 'Device|x.\s' I get the following columns as output device rrqm/s wrqm/s r/s w/s rsec/s wsec/s avrq-sz ...