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

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1
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1answer
32 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 ...
2
votes
1answer
767 views

CentOS 5 - hdparm - how to set DMA mode

I'm running CentOS 5 with a PATA hard drive. I've used hdparm to tune the hard disk for better performance, but there are 2 settings that don't work: hdparm -M 254 /dev/hda gives the error ...
35
votes
4answers
40k views

How can I safely remove a SATA disk from a running system?

I sometimes need to plug a disk into a disk bay. At other times, I have the very weird setup of connecting a SSD using a SATA-eSATA cable on my laptop while pulling power from a desktop. How can I ...
7
votes
1answer
94 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 ...
1
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0answers
17 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
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0answers
13 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 ...
0
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0answers
21 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
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1answer
33 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
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1answer
2k views

“Spare” disk in a 2-disk mdadm RAID1 array?

I recently had a RAID1 volume fail. It had three primary partitions in it, all participating in separate, but similarly configured VGs. This configuration comes from the fact that the machine is ...
1
vote
1answer
26 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
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1answer
54 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
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4answers
815 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 ...
2
votes
1answer
986 views

Problem creating raw disk image and mounting it in rescue mode to QEMU

I am trying to create booting system from raw disk image. This is what I do: $ dd if=/dev/zero of=system2.img bs=1M count=6000 6000+0 records in 6000+0 records out 6291456000 bytes (6.3 GB) copied, ...
3
votes
1answer
35 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 ...
0
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0answers
20 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 ...
1
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4answers
124 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?
0
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1answer
54 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 ...
0
votes
1answer
47 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 ...
2
votes
1answer
39 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
31 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 ...
3
votes
3answers
5k views

Mounting another VM's .vdi in VirtualBox

I have two VMs in VirtualBox. For exmaple, VM 1 runs Red Hat, and VM 2 runs Ubuntu. For the Red Hat VM I have redhat.vdi and redhat2.vdi, and for the Ubuntu VM I have ubuntu.vdi and unbuntu2.vdi. ...
0
votes
0answers
11 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
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0answers
41 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
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1answer
35 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
30 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 ...
0
votes
0answers
22 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
51 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 ...
1
vote
3answers
5k views

Disk on key is read only on every computer

I have a 16 GB SanDisk Cruzer Blade Disk-on-key. After a few days of use, it has become write-protected/read-only. When I plug it in, you can see this in my Ubuntu's dmesg: [ 819.003359] usb 2-5: ...
1
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1answer
39 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 ...
3
votes
0answers
46 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
36 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 ...
2
votes
1answer
66 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 ...
0
votes
1answer
40 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" ...
39
votes
11answers
71k views

List partition labels from the command line

Is there a command that will list all partitions along with their labels? sudo fdisk -l and sudo parted -l don't show labels by default. EDIT: (as per comment below) I'm talking about ext2 labels - ...
0
votes
1answer
36 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 ...
1
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0answers
27 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 ...
7
votes
2answers
7k views

Eject / safely remove vs umount

I'm using Ubuntu 12.04, and when I rigth click on a my flash drive icon (in the Unity left bar) I get two options that have me confused: eject and safely remove. The closer I came to answer was this ...
2
votes
5answers
6k views

What is the /dev/disk/by-uuid/ and why does it use all free space on the disk

I have the following Debian that works in Virtual Box: $ uname -a Linux debian 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 x86_64 GNU/Linux Recently I notice that I don't have any free space: $ df ...
1
vote
1answer
49 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
56 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
419 views

WRITE SAME manually zero

With Debian 8 and VMware 6 I am seeing these logged quite a bit: WRITE SAME failed. Manually zeroing messages. Is this something to be concerned about? From searches, it seems its related to the 3.9 ...
1
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1answer
37 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
12 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
31 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
71 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
36 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 ...
0
votes
1answer
57 views

Cant mount disks

I have a windows 8 ,ubuntu dual boot system. when i open kali . i cant see any of the hard disk partitions . i receive the following error message . Error mounting /dev/sda1 at ...
7
votes
2answers
1k views

FreeBSD 10 trace disk activity

Is there any way to find some process which is periodically writing to disk (according to hdd led) on FreeBSD 10 with ZFS (maybe turn ZFS into verbose logging mode)? lsof and other instantly ...
3
votes
1answer
86 views

Performance differences when writing into /dev/sda and into /mnt/sda/tempfile

I am testing my new PCI-E SSD in Linux. I am using the following command to test its performance (reference: https://www.thomas-krenn.com/en/wiki/Linux_I/O_Performance_Tests_using_dd) (1) dd ...