Questions tagged [iostat]
The iostat tag has no usage guidance.
83
questions
3
votes
0answers
27 views
Are My Drives Being Utilized Equally with Linux Software RAID 0 Array?
I have four NVMe drives in a RAID 0 configuration.
I am attempting to determine how many IOPS the array is handling.
When I run iostat, it appears that one drive is handling more IO than the other ...
3
votes
0answers
105 views
Can iostat output show mismatched read data for mdadm raid5 array?
I'm trying to understand this iostat output:
tps kB_read/s kB_wrtn/s kB_dscd/s kB_read kB_wrtn kB_dscd Device
500.30 58.9M 19.4k 0.0k 329.1G ...
1
vote
2answers
226 views
What could cause high iostat await if a disk isn't overutilized?
I have a database running on GCP. Occasionally it gets very slow for a period of minutes (like average statement execution time spikes by 10x or more). The slowness is correlated with increases in the ...
google-cloud-platform
0
votes
0answers
24 views
systems requirement planning [duplicate]
I am running Ubuntu server 20.04 LTS in a VM hosted on a NAS (Synology.) Primary purpose of this system is to ingest data for ELK. This is the master node.
Configuration is:
Compute: Intel Celeron ...
2
votes
0answers
180 views
iotune qemu/KVM total_iops total_bytes limits
I have created some qemu/KVM virtual machines on SSDs.
The host has ~6 SSDs. 1 is being used for the OS, and each of the other SSDs has two VM guests.
I'm using iotune to limit the capabilities of ...
0
votes
0answers
178 views
How does avgqu-sz size in iostat output relate to r_await and w_await?
Can someone explain what does avgqu-sz mean in the output of iostat? The manual page states like this.
avgqu-sz:
The average queue length of the requests that were issued to the device.
Can ...
1
vote
0answers
65 views
Difference in utilisation reported by iostat for two identical disks in RAID1
I'm trying to debug some weird behaviour with Postgres performance and am trying to understand the iostat output. I'm on 2x SSD on RAID1. Why would one of the disks be reported at ~21% utilisation ...
0
votes
1answer
269 views
iostat %util for NFS mounted shares available?
Is there a way to calculate, from the client, the "% util" of NFS mounted disks?
I know with iostat, with locally mounted disks you can see %util
Device: rrqm/s wrqm/s r/s ... ...
1
vote
1answer
805 views
What does iostat show a different utilization for the 'dm' device?
I installed an M.2 drive into a Proxmox host this morning and monitored the disks with iostat -x 1. Why is iostat showing dm-7 is at 98% utilization, while the M.2 LVM PV (nvme0n1p1) shows only 6.8?
...
1
vote
1answer
1k views
What are the parameters in iostat
I used iostat and trying to understand the iostat output using this link : https://linoxide.com/linux-command/linux-iostat-command/ but It is not clearly explained.
PF the output at different times ...
1
vote
1answer
72 views
How to find good state io stats?
I would like to monitor disk I/O activity in case something courses heavy I/O. This Nagios plugin seams simple, where he gives examples of
Example: Tps, read and write thresholds:
./...
1
vote
1answer
501 views
iostat showing wait queue when device is not 100% busy
I am on Solaris 11 and I am seeing the following
%w=32
%b=62
extended device statistics
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
47.5 2564.6 1460.1 33481....
0
votes
3answers
338 views
modify iostat -t time output format
I was trying to plot the results of various iostat results. For that I want to use https://clusterbuffer.wordpress.com/file-system-tools/iostat_plot/iostat-plotter-v3/.
Anyhow - for some ...
0
votes
2answers
78 views
How to determine if I/O is slow for server
I have used I/O stat to check whether my server's I/O is slow or not. The % util is high but so is the read/sec - write/sec. Can anyone help ?
Following is the output of iostat -mx command
Linux 2.6....
2
votes
0answers
123 views
Resetting disk table in zfs pool
In Our Solaris 11.3 zfs storage server, one disk in the pool died, we replaced it. Everything is working fine, but iostat is still showing old disk with large error count. This is bothering our ...
3
votes
1answer
831 views
Why are cpu usage percentage different between top and iostat?
On a heavily loaded database server, I am getting vastly different output from top and iostat for cpu usage. Why might the value be different?
top:
%Cpu(s): 84.7 us, 11.8 sy, 0.3 ni, 2.4 id, 0.6 ...
0
votes
1answer
762 views
How to get gcc installed on CoreOS hostmachine rather than the containers running inside it
I have an external monitoring tool that connects over ssh periodically and checks the various system params of a linux box (cpu, mem, etc.). However this approach does not work with CoreOS since it ...
11
votes
1answer
6k views
(A Windows guy asks) Measuring Disk Latency on Linux: Do I bother?
On Windows, whenever I want to validate / confirm that there might be IO-related issues on a volume that a database or other low-latency app lives on, I check disk latency.
If I see the Windows ...
0
votes
3answers
621 views
e2fsck takes lot of time to run
I am running e2fsck on one of my disk partitions (ext4) but it seems to take eternity. It is already running now for almost 10 hours or so and it is still at 42%. The size of the partition is around ...
0
votes
0answers
130 views
Nagios php script to read iostat values
I'm working on a php script(nagios plugin) to read r/s,w/s,rMB/s,wMB/s,%util from the iostat command, e.g.
#iostat -xm sda
avg-cpu: %user %nice %system %iowait %steal %idle
1.05 0....
2
votes
2answers
163 views
physical vs logical disk transactions
I'm trying to analyze server requirements for a set of virtual machines. We're using LVM on them, so iostat shows numbers for both the logical volume and the physical disk, and they often don't match ...
1
vote
1answer
539 views
Linux “iostat” to .csv file using Perl
I am experimenting with the iostat -c 1 command, and I was wondering if there is a simple way of reading the current output and then separating the values so that I could generate a .csv file.
The ...
1
vote
1answer
757 views
NFS read/writes since startup
I'd like to retrieve the total number of kilobytes read/written for each NFS mount point.
Using the following commands, I'm able to see the current throughput for each NFS mount point in kB/S.
...
0
votes
1answer
188 views
Bytes read / written SNMP value differs from iostat
I am trying to monitor my server over SNMP and UCD-DISKIO-MIB::diskIONRead.1 gives me 1344574464 while iostat reports 9701669 kB_read. Why the discrepancy? I don't have to mention that I am monitoring ...
0
votes
0answers
47 views
No w/s in iostat output even though wMB/s is high
I am trying to format a 2 TB SAN based block device (/dev/mapper/mpathb). Even though, mke2fs has been running since over one hour without completing, iostat -z -x -m 10 output in a separate terminal ...
2
votes
1answer
209 views
HP UX iostat on File System
I have a server running HP UX 11 OS and I'm trying to have I/O statistics for File System and not disk.
For example, I have 50 disk attached to the server when I type iostat (here under output of ...
2
votes
0answers
661 views
Why are /proc/diskstats figures suddenly unbelievably low?
I have a Debian jessie server with two Intel DC S3610 SSDs in it, in RAID-10. It's reasonably busy for IO and for the last several weeks I've been graphing the IOPS:
As you can see, most of the time ...
1
vote
1answer
725 views
How many milliseconds of await is considered to be high? [closed]
How many milliseconds of await is considered to be high?
i have 800ms and 600ms
iostat -x
avg-cpu: %user %nice %system %iowait %steal %idle
1.28 0.00 0.22 0.90 0.00 ...
9
votes
1answer
21k views
what percentage of iowait is considered to be high?
when iowait is considered to be high ?
iostat -x
avg-cpu: %user %nice %system %iowait %steal %idle
2,89 0,01 5,45 49,83 0,00 41,83
Device: rrqm/s wrqm/s ...
0
votes
1answer
696 views
Not getting Proper output for check_iostat for nrpe plugins
My iostat is giving following output
$ iostat
Linux 3.13.0-29-generic (Inksedge) 08/13/2015 _x86_64_ (4 CPU)
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
xvdap1 ...
0
votes
1answer
282 views
Interpreting the IOstat result
Below are the results for iostats:
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
sda 120.94 10201.14 4354.87 64513033284 27540653120
sdb 63....
2
votes
1answer
51 views
iostat taking lot of time to return
I have a solaris 10 server with a lot of SAN disks (close to 1000 across all paths). iostat -En takes close to 5 min to return. Is there a way to figure out what is causing the delay? truss hasn't ...
1
vote
2answers
900 views
How to interpret iostat for a crumbling MySQL server
We have a combined application/MySQL-server which has started to crumble. Right now, it gets stuck on copying a 125 million row MySQL MyISAM table (INSERT INTO a_copy SELECT * FROM a with KEYS ...
1
vote
1answer
336 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
vote
1answer
600 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
votes
2answers
943 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
votes
1answer
2k 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 -...
9
votes
1answer
14k 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 ...
3
votes
2answers
1k 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 ...
1
vote
1answer
188 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
959 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
vote
0answers
645 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
2k 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
892 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 ...
1
vote
2answers
512 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
199 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 ...
0
votes
4answers
20k 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
...
4
votes
3answers
5k 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?
2
votes
2answers
224 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 ...
3
votes
2answers
3k 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
...
