All Questions
Tagged with performance io
18
questions with no upvoted or accepted answers
4
votes
0
answers
2k
views
Why are pgpgin/s and majflt/s inconsistent in sar -B?
In sar -B ouptut, I would naively expect pgpgin/s to equal majflt/s multiplied by the system page size. From man sar:
pgpgin/s
Total number of kilobytes the system paged in ...
- 141
3
votes
1
answer
988
views
Linux: how can I determine if an application is doing sequential or random disk I/O?
Everyone knows that databases tend to do lots of small random I/O while big data things like Kafka tend to do large sequential I/O, but if I'm approaching this as a sysadmin without making assumptions,...
- 2,655
3
votes
0
answers
54
views
Do I need to create multiple filesystems on a virtual server to increase I/O performance?
I want to install Oracle on a virtual server. I don't really know the technology behind, my company just gave me a virtual server with multiple (virtual) disks.
I have the possibility to divide those ...
- 83
2
votes
0
answers
612
views
Access disk io data in linux without tools like iotop/iostat to find processes or files with IO
We have regularly high load average. With the help of a zabbix agent, I could narrow it down to be mainly because of cpu iowait (and lastly disk io). I am not allowed to install any additional ...
- 121
2
votes
0
answers
192
views
"Nosy Neighbor" and the CFQ scheduler
I'm trying to understand how does using CFQ affects the "Nosy Neighbor" problem.
I'll ask it a bit naively, can a "Nosy Neighbor" even exist when using CFQ? Isn't that CFQ should make sure all ...
- 123
2
votes
0
answers
1k
views
Reason for high CPU time when executing fio
After weeks of troubleshooting some performance issues I have on my VPS running Ubuntu 12.04 LTS, I am getting closer to the conclusion that the problem is related to IO.
When I have a considerable ...
- 93
1
vote
0
answers
66
views
Couchdb 3.1.1 increases disk latency gradually over weeks
I've been dealing with this issue for weeks now.
I have the followin scenario:
couchdb2.3.1-A <===> couchdb2.3.1-B <===> couchdb3.1.1-A <===> couchdb3.1.1-B
where <===> ...
1
vote
0
answers
140
views
disk I/O latency spikes (contains log files from amplify)
Ubuntu 18.04 LTS server, disk is ssd. Application stack is: mongodb, node, nignx and some python.
Server is up 1 month and already had 3 OS disk fails where Ubuntu would go in read only mode. After ...
1
vote
0
answers
674
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 ...
- 333
1
vote
0
answers
451
views
Give read operations priority over write
I'm working on a system where I have a program that outputs high quality videos for a tv connected to an HDMI (raw 1080p data for instance) and I'm having an issue that when I copy some files to my ...
- 41
1
vote
0
answers
39
views
Long Response Times for Reads via FCoE
We're getting some intriguing performance with our new FCoE environment, and I was hoping that people could let me know if what we're seeing is expected behaviour.
Our switching environment consists ...
- 842
1
vote
0
answers
269
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 ...
- 457
1
vote
0
answers
160
views
File IO being slow
I've rented this root server with a RAID1 mdadm software raid setup.
Using dd to benchmark the file IO speed it achieves 230MB/s write (default blocksize). Certain tasks such as mysql are way slower, ...
- 111
1
vote
0
answers
121
views
File I/O Throughput
I have an IBM x3650 M4 server (64-bit) running Ubuntu 13.04 Desktop (32-bit). I realize that this is a non-standard setup by it's being driven by other requirements. I am seeing slow file writes ...
1
vote
0
answers
86
views
Chrooted from LiveCD: Bad IO performace
my Ubuntu Server installation is broken, so I grabbed a Ubuntu Desktop CD, mounted my Ubuntu installtion on my hard disk and chrooted into it.
But now my IO performance is really bad:
# time dd if=/...
- 11
0
votes
0
answers
620
views
How to find the bottleneck for slow rsync
I want to find the bottleneck for a slow rsync.
I see these parts (on byte flow order):
IO on source
CPU on source
Network
CPU on destination
IO on destination
How can I debug this?
- 3,603
0
votes
0
answers
2k
views
High disk usage in CSRSS.EXE
I recently started working on the server for a certain software (Tango). The users complained that it recently became extremely low, so I used an application (ProcessHacker) to see the resource usage ...
- 1
0
votes
0
answers
170
views
Two servers with inconsistent disk speed
I have two servers of identical spec (bought at the same time), except for the drive configuration:
Server A:
C: and D: drives are partitions on the same 2 disk RAID 1
E: is a 2 disk RAID 0
Server ...
- 183