Server Fault Stack Exchange
Server Fault Stack Exchange

Questions tagged [io]

IO (or I/O) is an abbreviation for input/output, most commonly referring to disk input/output.

IO (or I/O) is an abbreviation for input/output, most commonly referring to disk input/output.

401 questions
4
votes
3 answers

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 histogram form) I can already figure out our reads/writes on a…
Michael Pearson
  • 145
  • 3
  • 8
4
votes
2 answers

monitor IO to tmpfs partition?

How can I monitor the write speed to a tmpfs partition. It does not appear in the output of vmstat or iostat. I am running several python processes that are writing heavily to tmpfs and contributing to load. The load is high but the CPU, memory,…
CarpeNoctem
  • 2,437
  • 4
  • 23
  • 32
4
votes
2 answers

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 0.0 3:23.83 cp -i -r 165 178 temp Why does…
Boaz
  • 2,229
  • 5
  • 20
  • 15
4
votes
3 answers

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 usage. This uncovered some interesting stats for…
RodH257
  • 569
  • 6
  • 11
  • 23
4
votes
2 answers

/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 running any services that should require much…
staticfloat
  • 257
  • 1
  • 3
  • 8
4
votes
1 answer

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?
Thomas L Holaday
  • 1,353
  • 4
  • 16
  • 19
4
votes
4 answers

MySQL, disk I/O and SSD drives

We have a LAMP box with 2x mirrored 1 TB WD Black Caviar disks running the whole OS and MySQL. 8 GB / RAM, 2x quad core CPUs. We're really taxed on disk I/O, and I've been thinking of suggesting getting a couple SSD drives in there for…
Stephen J. Fuhry
  • 154
  • 1
  • 8
4
votes
1 answer

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 or the like. I need to know: The number of…
Daniel
  • 844
  • 7
  • 24
4
votes
1 answer

High disk time on SQL Server

We have a dedicated SQL Server 2008 R2 Enterprise Edition. The setup is: D: (data files) - stored on local ssd disks (not the same disks as log files) (raid 10) E: (log files) - stored on local ssd disks (not the same disks as data files) (raid 1)…
Patrik
  • 51
  • 6
4
votes
3 answers

High Load - Low IO - Low CPU usage

I have a system whose load is rather high. As you can see from the top output below, CPU usage and I/O is negligible: top - 17:31:59 up 4 days, 2:34, 2 users, load average: 1.00, 0.99, 1.00 Tasks: 71 total, 1 running, 70 sleeping, 0…
devup
  • 51
  • 1
  • 4
4
votes
2 answers

Use F2FS on RAID0 within HDD?

My server contains 128 monitors and that caused many random write IO be submitted. If I use SSD, many writes will make it broken soon. I read some articles about F2FS and know it works better on flash disk and random/small writing. There are many…
code_worker
  • 161
  • 6
3
votes
1 answer

How to accelerate metadata (getattr) requests on an NFS file server for fast locally-cached reads?

We have a storage server with a 12 disk RAID-6 pool of 100 TB. It is used by several client compute nodes via NFS, mostly running deep learning training (lots of images ~100 KB, loaded in random order). To speed up file access, we use cachefilesd on…
isarandi
  • 341
  • 2
  • 11
3
votes
3 answers

Are there any industry standards for network timeout or / IO timeout etc?

I was reading this article about microbursts: https://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/white-paper-c11-733020.html which can also cause traffic drops. So, as these microbursts are inevitable and can't be…
GP92
  • 681
  • 2
  • 9
  • 27
3
votes
1 answer

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, how do I determine what a running application…
Michael Martinez
  • 2,645
  • 3
  • 24
  • 35
3
votes
1 answer

What does the nomerge mean in Linux system?

We can see some parameters by issuing "iostat -x -d", the rrqm/s and wrqm/s stand for the merge for I/O request per second. And there is a kernel parameter controlling the I/O merge: /sys/class/block/device-name/queue/nomerges According to the…
Jepsenwan
  • 170
  • 3
  • 12
1 2 3
…
26 27