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

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4
votes
1answer
756 views

Edit file on image created with dd [duplicate]

I've a bootable USB with Debian. Normally I clone the disk with dd, write the image on a new USB disk, mount this disk on my filesystem and edit some files. Is it possible to edit files on the image ...
0
votes
2answers
396 views

How to get total disk read/write in bytes per hdd device from /proc

How to get total disk read/write in bytes per hdd device? for example if i have sda, sdb, and sdc, is there any file on /proc that i could use similar to /proc/net/dev for networking?
2
votes
4answers
2k 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 ...
5
votes
2answers
696 views

How to create a fixed size Linux ramdisk which does never swap to disk?

I want to create a fixed size Linux ramdisk which never swaps to disk. Note that my question is not "why" I want to do this (let say, for example, that it's for an educative purpose or for research): ...
0
votes
1answer
197 views

Is there something wrong with df output? [duplicate]

I'm using the command df -h to check disk usage on CentOS 6.4. I see an inconsistency with the output. look at the line Filesystem: total 490Gb, used 55Gb, and Available 411Gb. What is it mean? I ...
1
vote
3answers
479 views

/dev/disk/by-uuid/ not working on one machine

I have a iSCSI disk which I am mounting from several machines (exclusively, not concurrently). On machine A, I start iscsi service open-iscsi start and the iscsi disk is discovered as /dev/sdb1. ...
2
votes
1answer
2k 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. ...
3
votes
2answers
70 views

Uniquely identifying a drive (not a partition)

I'm writing some automation scripts for full disk backups and I'd like to be fairly precise with which devices are used. I know that one can uniquely identify a partition using UUIDs and blkid, but ...
2
votes
2answers
512 views

How do I navigate to a CD drive?

I'm trying to install Virtualbox Guest Additions in Elementary OS. cd doesn't seem to work with cd VBOXADDITIONS_4.2.6_82870. Update: I did what @ivica recommended, and here's what I'm getting: I ...
0
votes
1answer
68 views

How to create memory-based disk in linux? [duplicate]

I need to have a very fast disk for keeping cache. How can I do that in Linux?
9
votes
5answers
5k views

Given a kernel ATA exception, how to determine which physical disk is affected?

I woke up this morning to a notification email with some rather disturbing system log entries. Dec 2 04:27:01 yeono kernel: [459438.816058] ata2.00: exception Emask 0x0 SAct 0xf SErr 0x0 action 0x6 ...
4
votes
2answers
906 views

How does Linux md-RAID handle disk read errors?

There are 2 cases: the read command times out at kernel level (30 seconds by default), the drive reports its unability to read a given sector before the kernel lose patience (the case I'm ...
2
votes
1answer
359 views

Difference between “blockdev --flushbufs” and “sync” on Linux?

Is there a difference in practice between running blockdev --flushbufs and sync(1) on Linux? (apart from blockdev flushing for a specific device, and sync being system-wide). sync(1) manpage says it ...
2
votes
2answers
1k views

Free space: 0 bytes and files full of data shown as empty

I don't know what's going on. The last evening I left my computer with about 700MB of free space on the system partition and today there is no free space on disk, moreover a lot of files containing ...
1
vote
1answer
110 views

Repartion multiple disks and reallocate storage

I’m trying to re-partition from an Arch Linux install disc. I’m doing so because my current OS is corrupted. When running fdisk –l this is what it looks like: /dev/sda1 * start=2048 end=1026047 ...
3
votes
2answers
3k views

How to Add Extra Disks on KVM based VM

I installed Redhat 6.4 on KVM Server. Right Now there is only One Disk /dev/vda. Now I need to add extra Disk like /dev/vdb I tried adding New Volume but it is not showing when I do fdisk -l How to ...
1
vote
0answers
198 views

How different is I/O handling of hard disk in AIX and Redhat Linux?

I am running a hadoop I/O workload in redhat linux and have ran that in IBM AIX as well with same underlying hardware, disk and disk configuration. With the default settings on the os redhat linux is ...
3
votes
4answers
423 views

How can I zero files out inside a VMware image file so that their space can be reclaimed?

is there a command on Linux to remove a file but zeroing it's contents first? so if i do, something like this: rm -rf /var/cache/pacman/pkg/* it would overwrite each file on that directory with 0 ...
1
vote
1answer
1k views

How to measure total disk I/O per hour

I have a cloud server were we get billed also for disk IO usage. Here is an example from the stats: 04/Sep/2013 07:24:19 04/Sep/2013 08:24:19 0,5 GB / 1 vCPU (0,08 Kr. per hour): Charge for ...
13
votes
2answers
1k views

How to detect if a disk is seeking?

I can use a variety of tools to measure the volume of disk I/O currently flowing through the system (such as iotop and iostat) but I'm curious if it's possible to easily detect if a disk is seeking a ...
6
votes
4answers
367 views

Are short-lived files flushed to disk?

My program creates many small short-lived files. They are typically deleted within a second after creation. The files are in an ext4 file system backed by a real hard disk. I know that Linux ...
1
vote
1answer
94 views

Strange problem with IO or file system or what?

On a SLES 11 SP2 32-bit system I'm seeing a strange problem. It's as if the OS can not open a file from the beginning of the file. Say I have a file that is 200 lines. If I cat or more or vi the ...
11
votes
3answers
2k views

How to get total number of bytes/sectors/blocks written to disk since booting?

I'm considering and update from HDD to SSD. But since Flash cells can only sustain limited writes. I want to know how much data my computer write during normal operation. So I can determine how long ...
1
vote
2answers
304 views

Setting up a RAID 1 in Funtoo [closed]

In short Following the guide How to Set Up a RAID 1 Under GNU/Linux, I have setup a RAID 1. Checking the RAID Array for validity in various ways, appeared to be normal. However, after rebooting the ...
1
vote
2answers
83 views

Create my own disk server

I have been wondering how all these small nas boxes that run linux can share over network and usb. The network part is totally under control, but I am completely at a loss on how I could hook up a ...
1
vote
1answer
67 views

Why I got a strange result for fdisk -l

root@host [~]# fdisk -l Disk /dev/sdc: 128.0 GB, 128035676160 bytes 255 heads, 63 sectors/track, 15566 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 ...
0
votes
4answers
652 views

Deleted files from home, deleted them from .local/share/Trash/files, System doesn't report back free space

I am running Crunchbang, a Debian variant with OpenBox WM. I have deleted a large number of files via browsing in thunar file manager and pressing del key. They disappear from view. I then go to ...
1
vote
1answer
490 views

Changing drives in FTP

I am using RHEL6 and I connect to FileZilla FTP Server in Windows 2008 Server which has more than 10 drives. I have access to all of them but for my user C:\ is Home Directory. I want to change to ...
5
votes
2answers
572 views

How do I refresh the magnetic state on a disks with backups?

I have a couple of large disks with backup/archive material on them. They're ext4. Regarding the ones of those that will be stored for a couple of years without reading the whole disc again I've been ...
0
votes
1answer
51 views

Redundant array of NTFS disks

I have a number of NTFS disks with unused capacity. They are leftover external hard drives with a Windows history. I have a very limited number of USB ports on my machine, and want to find a cheap way ...
1
vote
1answer
418 views

How to realign a disk on logical volume with minimum to zero down time

A system running un-align disk partition that needs to be aligned without loss of data on all the partition including mbr with the minimum to no down time.
3
votes
1answer
2k views

What's the easiest way to decrypt a disk partition?

I made a mistake of encrypting the entire LVM physical volume (contains both home, root, and swap) when installing a CentOS 6.4 (2.6.32-358.6.1.el6.x86_64) box. I soon came to realize that moving ...
0
votes
1answer
175 views

Disk Partitioning - Can't create partition

I've been following this example to restore capacity to my microSD --> SD card corrupt and stuck at 32MB, any way to fix it? Everything seems to work until I get to mkfs /dev/sdx1 It tells me ...
2
votes
3answers
239 views

Any programs suitable for making a database over disk-content?

I have quite a lot of external hard-drives, and often have a hard time finding what I'm looking for - not to mention not storing the same file several times on different drives or finding free space ...
2
votes
2answers
1k views

How to use DD to clone a partition off a disk image?

I have a disk image, it's a "whole" disk image, e.g., contains multiple partitions, and I want to clone just one of them (not the first one..) onto a partition on an external drive with multiple ...
7
votes
4answers
6k views

Is there a good drive torture test tool?

I have been having odd and rare filesystem corruption lately that I suspect is the fault of my SSD. I am looking for a good drive torture test tool. Something that can write to the whole disk, then ...
2
votes
0answers
146 views

Block Devices & Partitions

I partitioned a microSD card (mmcblk1) into two partitions mmcblk1p1 and mmcblk1p2. If use a dedicated card reader I am able to see the entire SD card and its partitions using various disk management ...
2
votes
1answer
193 views

Keeping disk caches when hibernating

Is there a way to keep disk caches when hibernating Linux? I understand and agree that dropping them is the best option all-around. But my system is unresponsive after resume and I would like to give ...
13
votes
3answers
768 views

Horrible situation - file systems mounted simultaneously by multiple independent OS instances

How do I get out of this situation safely? Details are as follow: A xen server has got block devices allocated to VMs. But these devices have also been mounted inside Xen. In fact 44 of these ...
1
vote
0answers
37 views

Reasons for choosing primary over logical partitions [duplicate]

I guess anyone knows the benefits of logical volumes. But are there any reasons why I should choose primary partitions if I can?
2
votes
2answers
1k views

Can't format external drive

I am trying to format an external drive, but getting the error /dev/sdb1 is apparently in use by the system; will not make a filesystem here! Based on the internet, I have to run cat ...
1
vote
1answer
94 views

Really umount external drive

I had a USB drive mounted on /dev/sdb1 and I want to reformat from NTFS to ext3. I did umount -l which unmounted the disk. I deleted the old partition using cfdisk. I ran mkfs.ext3, but got the error: ...
1
vote
2answers
5k views

UUID Of A drive that won't show up in /dev/disk/by-uuid or blkid

I have a USB drive that is not receiving a UUID. When I look at the contents of the /dev/disk/by-uuid it doesn't exist there. The dev point that the partition lives in is on /dev/sdb. I am able to ...
5
votes
2answers
4k views

Linux Mint freezes on startup

Premise I am running Linux Mint on my sister's computer. Everything was working fine, but than one day she turned it on and she got a strange message she didn't understand. I think it was some kind ...
1
vote
2answers
2k views

Using SAR to monitor free disk space data

Is there a way to make sar (from sysstat) collect free disk space data?
2
votes
3answers
5k views

Can I create a software RAID 1 with one device

I have a single disk that I want to create a Mirror of, Lets call this disk sda I have just bought another identicle size disk, which we can call sdb. sda and sdb have one partition called sda1 and ...
1
vote
0answers
1k views

How to set up ZFS with ZIL and L2ARC SSD?

I have been considering bcache and flashcache. However my friend suggested me something called ZFS. In fact it says that formating disk with ZFS can actually do the exact same thing without kernel ...
1
vote
3answers
118 views

Bad sector on a directory

I've a bad sector on my /home/xyz which make a folder with 10 GB data unreadable. As far as I can see in syslog there's only one badsector with may destruct 4K of data while I have no access to 10 GB ...
15
votes
8answers
13k views

How to determine which sd* is usb? [duplicate]

Possible Duplicate: How to know if /dev/sdX is a connected USB or HDD? The output of ls /dev/sd* on my system is - sda sda1 sda2 sda3 sda4 sda5 sda6 sda7 sdb sdc sdc1 sdc2 ...
2
votes
2answers
145 views

Why I have two /dev/sdx entries with a single disk?

In my laptop (running Linux) I have only one SSD, connected to the SATA3 port. Why I have two sdx entries in /dev directory? In particular I see /dev/sda and /dev/sdb, and /dev/sda is the SSD: # ...