-1
votes
2answers
24 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 ...
2
votes
2answers
141 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 ...
1
vote
2answers
930 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 ...
2
votes
2answers
315 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 ...
10
votes
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
votes
1answer
149 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 ...
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 ...