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On my local machine, I have /sys/block/sda1/stat.
On an Amazon machine, I have /sys/block/xvda1/stat.

When I run cat /sys/block/sda1/stat or cat /sys/block/xvda1/stat both give 11 fields of output.

What is the difference between /sys/block/sda1/stat and /sys/block/xvda1/stat files?

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  • You can see difference between two files by using diff command, by the way. Commented Aug 26, 2015 at 13:05
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    @ MatthewRock did u understand my question ? Commented Aug 27, 2015 at 12:11
  • Yes. That's why I said "by the way". You ran cat on both files, so you probably have tried comparing them. I just said that diff might be more useful than comparing it manually. I'm not answering your question, just throwing in a comment. Commented Aug 27, 2015 at 12:14
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    @ MatthewRock Better look at the answer. don't comment anything without understanding. i know diff command ok. Commented Aug 27, 2015 at 12:18
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    Sometimes I really want to be able to down-vote a comment. Commented Mar 8, 2016 at 5:37

2 Answers 2

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The /sys directory is generally where the sysfs filestystem is mounted, which contains information about devices and other kernel information.

The files in /sys/block contain information about block devices on your system. Your local system has a block device named sda, so /sys/block/sda exists. Your Amazon instance has a device named xvda, so /sys/block/xvda exists.

The /sys/block/<dev>/stat file provides several statistics about the state of block device <dev>. It consists of a single line of text containing 15 decimal values separated by whitespace:

Name units description ---- ----- ----------- read I/Os requests number of read I/Os processed read merges requests number of read I/Os merged with in-queue I/O read sectors sectors number of sectors read read ticks milliseconds total wait time for read requests write I/Os requests number of write I/Os processed write merges requests number of write I/Os merged with in-queue I/O write sectors sectors number of sectors written write ticks milliseconds total wait time for write requests in_flight requests number of I/Os currently in flight io_ticks milliseconds total time this block device has been active time_in_queue milliseconds total wait time for all requests discard I/Os requests number of discard I/Os processed discard merges requests number of discard I/Os merged with in-queue I/O discard sectors sectors number of sectors discarded discard ticks milliseconds total wait time for discard requests

So, each block device will have its own statistics file, hence the different values.
See kernel docs for more details.

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  • Am agree with your ans. Commented Aug 26, 2015 at 13:01
  • Can you please tel me how do i find block device name in different machine? Commented Aug 26, 2015 at 13:02
  • Well, you can look at the names of directories in /sys/block. Commented Aug 26, 2015 at 13:03
  • Also, find /dev -type b. Commented Aug 26, 2015 at 13:06
  • No worries. I had left this out as an RTFM issue, but I guess it's fine to have it here. Commented Aug 26, 2015 at 13:24
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Both files contain the statistics of the first partition (/sys/block/sda1/stat) of the first device (/sys/block/sda1/stat) found by a particular driver or subsystem. The difference is the driver.

Your amazon VM is using the Xen driver (/sys/block/xvda1/stat).
Your local machine is using the SCSI driver (/sys/block/sda1/stat).

xvd = Xen Virtual Disk

sd = SCSI Disk

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  • Worth noting WHY the names are different. Commented Aug 26, 2015 at 17:30
  • That was, from what I understood, the question. Commented Aug 26, 2015 at 21:13

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