Questions about disk drives under the UNIX and Linux systems. See also the "filesystems" tag.

learn more… | top users | synonyms

0
votes
1answer
42 views

How do I create a dd IMAGE from LVM for recovery purposes [duplicate]

How do I backup a LVM partition to an image for recovery purposes? I am trying to run dd on /dev/sda2, but it crashes after ca 8 hours, at around 380G sudo lvmdiskscan /dev/centos/swap [ 3....
0
votes
1answer
11 views

Since when Disks statistics in `top` command are counted?

I've got these disk statistics shown in top command: $ top | head | tail -n1 Disks: 1095425909/52T read, 1016012571/52T written. It's quiet high number for only 37 day uptime. Are these numbers ...
3
votes
0answers
15 views

“leaky bucket” style disk io throttling using linux kernel

My goal is to prevent one kvm guest's disk i/o usage from negatively affecting other kvm guests on the same host. The host has one disk array - and separating guests onto different physical disks is ...
1
vote
1answer
24 views

Use SWAP as disk cache in Linux

I am using different kind of disks on my server. Is it possible to use faster disk as SWAP and ask Linux to use it as Disk cache As I understand Linux use SWAP only for application data not disk ...
2
votes
1answer
40 views

How can I differentiate disk I/O occured explicitly by a user and OS prefetching?

I am monitoring disk I/O usages of an application program (running on CentOS 7) It uses lots of sequential disk I/Os where I expect that OS prefetching is something! dstat shows how many disk I/Os ...
0
votes
2answers
36 views

Debian Disk Manager Problem

I have just installed Debian 8.5 Jessie on my computer and I can't find a disk manager. Then I wrote this command to terminal: apt-get install disk-manager. A software installed and I tried to start ...
1
vote
1answer
31 views

How can I tell when my file system was last fsck-ed at all?

I know of various ways in which to check when the last fsck occurred on a file system. e.g. $ sudo dumpe2fs -h /dev/sda1 | grep 'Mount count' -A3 dumpe2fs 1.42.12 (29-Aug-2014) Mount count: ...
1
vote
1answer
23 views

lsusb not listing a SCSI drive, connected through USB (SATA bridge)?

I'm looking at one of those detachable hybrid laptops, which has extra hard drive in the keyboard base; this laptop runs Ubuntu. Sometimes these drives mount at startup, sometimes not - and in ...
1
vote
0answers
16 views

iozone read test slower than fio

I'm currently using both iozone and fio to test my disk performance. However, iozone show much much poor speed than what is shown from fio. (about 1/3) Now the question for me is which number should ...
1
vote
0answers
13 views

Extending XFS filesystem CentOS 7 Google Cloud

I have Googled everything, and literally nothing is working. Here is df -h: Filesystem Size Used Avail Use% Mounted on /dev/sda1 10G 7.7G 2.4G 77% / devtmpfs 103G 0 103G ...
2
votes
1answer
33 views

How does iotop calculate the relative I/O activity?

I am running some heavy I/O processes on my workstation and recently installed iotop to monitor them. Here's a recent screenshot: I'm a bit confused about the readings in the IO> column. It ...
1
vote
0answers
25 views

Reclaiming disk space in Ubuntu

In VMWare the hard disks took 13.6 GB, But with df, only 5.8 GB is occupied I don't quite get it. This Virtual Machine has no snapshots, and I already clicked on refresh button in VMWare Fusion ...
1
vote
1answer
22 views

What are the pros and cons of badblock's two non-destructive tests?

I use badblocks to test my 32GB class-10 microSD card that I use to boot my RPi. I already have a functioning file system on it, so I don't want to scan it with the -w option (destructive read-write ...
1
vote
1answer
47 views

Is there a way to monitor disk i/o patterns? (i.e. random or sequential i/o?)

While an application is running, I can monitor disk bandwidth usage using linux tools including dstat. Now I'd like to know how many sequential or random disk I/Os are occurring in the system. Does ...
1
vote
0answers
26 views

Determine affected file given logical block number [duplicate]

Given the logical block number from these log lines in /var/log/messages, is there a way to determine what file was affected? ...Buffer I/O error on device sdd1, logical block 203953715 ...lost page ...
2
votes
0answers
20 views

How to shrink sda disk with XFS filesystem

We have a RHEL 7 server with 2 disks (sda and sdb). Our /, /var/log and swap are on sda, /var is on sdb. We use LVM and XFS. sda is too big (160 GB) and we would like to shrink it to 40 GB. We can ...
7
votes
1answer
134 views

Command to generate /dev/disk/-by-path/ name on a system without udev daemon

On most Linux systems udev usually creates symlinks in /dev/disk/by-uuid/ /dev/disk/by-path/ which point to actual device nodes (/dev/sda, /dev/sdb, etc). I don't have udev on my system, and I ...
0
votes
0answers
22 views

Ubuntu trusty format disk slower than RHEL7?

I observed that disk formatting is much slower in Ubuntu than in RHEL7. Does anybody know why that is? EDIT: Forgot to mention, I'm formatting the disk with ext4. Using mke2fs
1
vote
1answer
29 views

How to know what exactly is being written or which process is keeping my storage disk busy?

I have a server , which has gone rogue(not really), i ran nmon and saw that its Disk utilization is BAD, its 100% busy writing!! Here is the output : Can someone tell me what is keeping my disk ...
0
votes
1answer
76 views

Struggling to remove a faulted ZFS pool on Centos 7 using zpool

I have been doing lots of testing of ZFS recently on a new server. I'm ready to move this server into production now, but I'm wondering if I can get rid of my old 'faulted' diskpools before I do, ...
4
votes
4answers
1k views

What is this dd if=/dev/zero of=/dev/sda do

Could someone help me understand what I got? dd if=/dev/zero of=/dev/sda bs=4096 count=4096 Q: Why specifically 4096 for count? dd if=/dev/zero of=/dev/sda bs=512 count=4096 seek=$(expr blockdev --...
0
votes
0answers
28 views

sfdisk does not create block files for corresponding partition

I have partitioned my disk using sfdisk. And the (7)partitions got created successfully. sfdisk -l also lists all the (7) partitions which I configured. But the strange thing is, the corresponding ...
3
votes
1answer
48 views

Why is the block size of a partition smaller than that of the underlying disk?

My understanding is that the block (in the phrase "block size") is like an IO buffer, or minimum IO size for a device. Since partitions are built on top of physical devices, how can they have blocks ...
1
vote
4answers
146 views

How to get hard disk information on linux terminal? [duplicate]

We can get CPU information using lscpu command, is there any command to get hard disk information on Linux terminal, in a similar way?
1
vote
1answer
79 views

Load disk driver during Debian installation

I have a server with all disks connected to a controller LSI 3008 IT (non-RAID mode). Unfortunately disks are not detected during installation of Debian Wheezy. Nevertheless the controller can be ...
0
votes
1answer
109 views

Replacing a failed disk in a ZFS pool

I've got a large ZFS disk pool; 3 nested RAIDZ2 vdevs. I am documenting the process for replacing a failed disk for my colleagues and so simulated a disk failure by removing a disk from the host. ...
0
votes
1answer
20 views

Checking for a failed drive in a ZFS pool

I'm testing a large ZFS pool at the minute and am documenting the process for replacing a failed drive before our environment moves into production. I've built the ZFS volume 'diskpool', which is 3 ...
2
votes
1answer
81 views

Move free space from end of the drive to first partition with gparted

I am in a frustrating situation - no matter how I try, gparted won't let me assign the empty space to the first partition: The middle partition is blocking me from expanding /dev/sda1. I need to ...
0
votes
0answers
37 views

Random write on DISK benchmark shows high read rate on iostat

I am running a random write benchmark directly on some disks (HDD & SDD) and I am getting some weird output data on the iostat monitor. Besides the usual write rate, there is a read rate that I ...
0
votes
0answers
14 views

How do I increase a partition size of a virtual disk?

I created a file using dd if=/dev/zero of=virt_disk bs=1024M count=50. I then formatted this is a vfat file system. Now I want to extend this. I added 5 more MiB of space as dd if=/dev/zero bs=1024M ...
0
votes
0answers
56 views

linux + resize2fs with Operation not permitted error

I am trying to increase the /opt to 65g but I get the following message Operation not permitted While trying to add group #8256 what is the resolution for that? root@linux:/opt # lvresize -L 65g /...
1
vote
1answer
67 views

Correspondence between SCSI device entries in /sys and the disks in /dev

Under the /sys/class/scsi_device folder I have the following: root@linux01:/sys/class/scsi_device # ls 1:0:0:0 2:0:0:0 2:0:1:0 3:0:0:0 How can I know how each of these devices is related to ...
1
vote
2answers
36 views

Can I use dd to move my system to another partition?

Currently, my whole system is located at the end of my hdd. I'd like to move that data to the beginning and still have booting and other details working. dd seems to do exactly what I want (to copy ...
1
vote
0answers
29 views

monitoring block access to disk

I am looking for a way to monitor access to disk blocks, and to monitor the access as a bitmap of blocks. I also need the capability to freeze (and queue) the device block access (and also to ...
1
vote
1answer
56 views

Where to tar entire USB flash drives?

I want to do all my archiving and compression on the command line. I have a USB flash drive located at /dev/disk/by-label/SanDiskData (which links to /dev/sdc1). I thought I could simply do: $ cd /...
0
votes
1answer
55 views

how do I make sda1 or sdb1 bigger

I'm working with Google Cloud services. After I've cloned a VM, I type lsblk after ssh'ing into it and can see that the partition sda1 is only 10 GB, which is only 10% of what I paid for. I am not a ...
1
vote
1answer
48 views

How to move image disk of a filesystem to a partition [closed]

I have a linux.img file with Arch Linux installed on it. I use the linux.img file to boot Archlinux on virtual machine. I got a new PC and will like to move the linux.img to new PC and boot it from a ...
2
votes
1answer
114 views

where can I find the disk latency using iostat ( await, svctm, %util )?

I'm using Redhat Linux 6.5 and would like to see the disk latencies for the used disks. Using iostat I get the columns await and svctm ( including %util ). But according to the man page of iostat ...
3
votes
0answers
49 views

Use a “Friendly” Label on Drives or Partitions in FreeBSD

Maybe I am missing this and it's really simple, but I cannot figure out how to label a BSD disk. I have looked at tunefs or gpart and even disklabel, however none do what I am looking for - I don't ...
0
votes
1answer
43 views

Only send email if disk usages exceeds 80%

My script is: abc=$(df -h | sed s/%//g | awk '{ if($5 > 80) print "Alert "$0;}' | awk '{print $2,$6}') \ && echo -e "Dear All, \n\n$abc\n\nABC" \ | mailx -s "Disk partition" ...
1
vote
0answers
29 views

iostat ( column svctm is not trusted any more ) what to use instead?

I'm running a Linux Server with "Oracle Linux Server release 6.5" which is pretty much the same as RedHat Version. I need to determine the latency on my disk devices. The man page of the iostat ...
0
votes
1answer
38 views

Where is the space from LVM partitions?

Additionally, output from my df -h command and fdisk -l command. Where and how could I utilize space from my /dev/sda4 and /dev/sda5 partitions? I suspect /dev/mapper/fedora-root to be my LVM ...
0
votes
1answer
41 views

Can't boot into my Linux partition--disk is supposedly at fault, but scans show no errors

I'm trying to boot into my Linux partition, but receive this message: Welcome to emergency mode! After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl ...
1
vote
1answer
61 views

Read ahead setting on Solaris

How to get the current read ahead setting on Solaris? On Linux it can be retrieved like this: # echo $(($(blockdev --getra /dev/sda)*512/1024)) (Assuming that blockdev always returns the read-head ...
2
votes
1answer
72 views

How to find unallocated disk partition with parted or another tool?

I'm using Fedora server and I have an unused partition on /dev/sda. How can I find it with parted or another command? I can only list mounted and used partitions.
1
vote
1answer
43 views

Is host-to-host file transfer possible using USB Type-C?

I'm doing a warranty replacement on my Chromebook Pixel 2, and want to transfer data from one laptop to another. The Pixel 2 has two USB type-C ports. I'm running Arch Linux on the old one. I'd like ...
0
votes
0answers
16 views

why does SCSI Host value change during reboot?

I have attached a virtual disk to my VM and the Host value changes during reboot. How can we bind it to a particular value? Host: scsi2 Channel: 00 Id: 00 Lun: 00 or Host: scsi3 Channel: 00 Id: 00 ...
3
votes
2answers
32 views

Installing Linux on hard disk that will be used by another computer with different hardware

I was given a laptop with a totally dead display. I do not want to pay to replace the broken display, but I would like to use the laptop as a server and connect to it via SSH to control it. I have ...
4
votes
2answers
87 views

Is `dd` really necessary to clone a disk? [duplicate]

Almost any tutorial will tell you that to clone a disk on the command line (say, to clone /dev/sda to /dev/sdb) you can use: dd if=/dev/sda of=/dev/sdb ...and some block size options... This reads ...
2
votes
0answers
41 views

unix c-shell : disk checking

im totally new in shell scripting. I have task to simplify an old c shell script. Basically, the script have 10 devices that using hp-ux and i want to check the disk space in each devices. my ...