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28
votes
4answers
2k views

How can I mount a block device from one computer to another via the network as a block device?

Is it possible to export a block device such as a DVD or CDROM and make it so that it's mountable on another computer as a block device? NOTE: I'm not interested in doing this using NFS or Samba, I ...
21
votes
3answers
10k views

How to know if a disk is an SSD or an HDD

I want to know whether a disk is a solid-state drive or hard disk. lshw is not installed. I do yum install lshw and it says there is no package named lshw. I do not know which version of ...
21
votes
6answers
5k views

How do I correlate /dev/sd devices to the hardware they represent?

A drive is beginning to fail and I only know the device by its /dev/sdb device file designation. What are the ways that I can use to correlate that device file to an actual hardware device to know ...
14
votes
8answers
6k 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 ...
13
votes
3answers
1k views

How to tell Linux Kernel > 3.0 to completely ignore a failing disk?

I am asking this question here in the hope that some Linux-kernel guru can have an answer. This question has been asked on AskUbuntu and on SuperUser without answers: thinking better, it is really ...
11
votes
2answers
1k views

Weight-based block IO control for VMs

I use KVM to manage my virtual machines. I am trying to limit the resources provided for VMs. I am able to limit the CPU and memory allocated for VMs using libvirt/cgroups. Now I want to control the ...
9
votes
1answer
663 views

What driver is behind a certain device file?

Given a device file, say /dev/sdb, is it possible to determine what driver is behind it? Specifically, I want to determine what driver my storage devices are using. fdisk -l lists 2 devices: /dev/sda ...
9
votes
4answers
1k views

Is there a way to sync only one partition?

Is there a way to sync only one partition instead of all partitions? Something like "sync /dev/sdc1".
8
votes
2answers
8k views

What are character special and block special files in a unix system?

How are character special files and block special files different from regular files in a Inix-like system? Why are they called “character special” and “block special” respectively?
8
votes
1answer
188 views

How to re-size partitions in a complete hard drive image?

I have taken a complete image of a hard drive using: dd if=/dev/sda of=/home/user/harddriveimg bs=4M It would seem to me, that I should be able to re-size the partitions within it after suitably ...
8
votes
2answers
472 views

Prevent disk renumbering on reboot in OSX

I have 3 physical drives in my Mac Pro with OSX 10.6.4. Occasionally after rebooting the machine, the disk numbering changes such that the /dev/disk# does not reference the same drive as it did before ...
7
votes
2answers
2k views

Find filesystem of an unmounted partition from a script

I'm writing a custom automated install using AIF (Arch Installation Framework), and I need to find the filesystem on a partition given a partition. So far I have this: grok_partitions () { local ...
7
votes
3answers
2k views

Mounting multiple img files as single loop device

Is there a way to take a disk img file that is broken up into parts and mount it as a single loop device?
6
votes
7answers
592 views

Make disk/disk copy slower

Is there a method of slowing down the copy process on Linux? I have a big file, say 10GB, and I'd like to copy it to another directory, but I don't want to copy it with full speed. Let's say I'd like ...
6
votes
3answers
3k views

How to read the in-memory (kernel) partition table of /dev/sda?

I accidentally overwrote my /dev/sda partition table with GParted (full story on AskUbuntu). Since I haven't rebooted yet and my filesystem is still perfectly usable, I was told I might be able to ...
6
votes
1answer
579 views

Run shell script when new volume mounted

I'm interested in running an rsync script whenever any new volume is mounted on my Debian box. What are some potential triggers / strategies for listening for a new volume mount?
6
votes
3answers
6k views

Prevent a USB external hard drive from sleeping

Does anyone know if there is an elegant way to tell an external usb drive not to spin down after a period of inactivity? I've seen cron based solutions that write a file every minute, but nothing ...
5
votes
3answers
4k views

Mapping between logical and physical block device names

I cannot figure out the mapping between different logical and physical block device names. The output of "cat /proc/diskstats" is : 104 0 cciss/c0d0 ... 104 1 cciss/c0d0p1 ... 104 2 ...
5
votes
1answer
393 views

Unmounting HTC device takes forever

Not sure if should post this on Android SE because I don't think this is directly related to the Android OS. On my system I manually mount and umount my HTC device with these options in /etc/fstab: ...
5
votes
1answer
2k views

Udev rule is not being used?

I'm setting up udev to handle my external USB hard drive when it gets plugged in and removed (no mounting yet). So far, I've made two new rules in /etc/udev/rules.d/10-local.rules to log ...
5
votes
3answers
2k views

Detecting that a device is mounted to a particular folder?

As part of revamping my backup scheme, I'm now adding rotating external hard drives, keeping one safely off-site at all times while the other is receiving backup data. Naturally, to ensure that my ...
5
votes
3answers
1k views

Does /init (or /linuxrc) script creates temporary device nodes in /dev?

Considering that GRUB executes following lines: kernel /vmlinuz root=/dev/sda1 ro initrd /initrd On boot, how does the Linux kernel finds out about /dev/sda1 device node? I know that ...
5
votes
1answer
777 views

How to determine if disk is compact flash or standard hard drive

I need to determine in a shell script if a given block device (e.g. /dev/sda) is a compact flash disk or a regular hard drive. Google did not help me out for once, and while udevadm info --query=all ...
4
votes
2answers
2k views

What is /dev/xvde1?

I'm having to do with an OpenShift RHEL Linux installation running on Amazon EC2. In the filesystem, there is a device file named /dev/xvde1 mounted to / ... and a device file named /dev/xvde2 mounted ...
4
votes
2answers
222 views

Determine what device a directory is located on

If I do # cd / # ln -s /home test # cd test # mount --bind $PWD /mnt the entry in /proc/mounts is /dev/sda2 /mnt ext4 rw,noatime,data=ordered 0 0 which is the device that is mounted to /home and ...
4
votes
2answers
230 views

List all the ways a block device is in use

I want to be sure that a removable hard drive (USB, but this shouldn't matter) is safe to remove. Let's say this drive is sdb. Obviously I need to make sure that there is no mounted filesystem on ...
4
votes
1answer
541 views

Find out if a specific device is an USB mass storage

Context I'm automating SD card imaging from an existing dd factory image. The SD card is always connected through an external USB card reader and thus appears in the system as a SCSI block device ...
4
votes
1answer
543 views

GNU/Linux: overlay block device / stackable block device

GNU/Linux has union mount that overlays dirs. So you can mount a writeable dir on top of a read-only dir. When the writeable dir is unmounted the read-only dir is untouched. I am looking for the same ...
4
votes
1answer
216 views

Can unformatted partitions have UUIDs?

Can a partition have a UUID without a filesystem?
4
votes
2answers
75 views

what is the etymology of `loop device`

What is the etymology of the term loop device Description: Wikipedia: loop device
4
votes
2answers
56 views

Finding an USB device path

Recently I saw this command posted on the internet: ls -l /dev/disk/by-label/ It worked, but I'm concerned, does it work on other Linux distros? How can I find USB device on the computer where USB ...
4
votes
2answers
166 views

why does blktrace only write blocks of 8?

I want to understand the I/O pattern a database is writing to disk to decide how many disks to use for best performance. To analyse the I/O pattern I want to use blktrace and I have to grok it first. ...
4
votes
2answers
3k views

Where is the GUID Partition Table stored on a device?

A friend of mine used my USB stick to install a new version of OS X on his mac. Now that I got it back, I wanted to wipe it (I use Linux myself). However, I'm having a bit of trouble doing so. The ...
3
votes
4answers
3k views

From df device name to physical drive name (vendor / type)

Seeing the device name by df, is it somehow possible to resolve it to the physical drive name such as vendor / type. /dev/sda3 915.4G 34.9G 880.0G 4% /share/HDA_DATA /dev/sdd3 ...
3
votes
3answers
724 views

When and why do block devices need to be partitioned? [duplicate]

Possible Duplicate: The merits of a partitionless filesystem So I've got a block device, say /dev/sda or /dev/loop0. Clearly if I want to boot from the former, or I want to subdivide it ...
3
votes
1answer
212 views

What permissions do I need to write to a card reader?

I have a card reader attached on /dev/sdb. What I do is giving all permissions to owner, group and the rest of the world, using: sudo chmod 777 /dev/sdb Can I just use another combination, ...
3
votes
3answers
5k views

Persistent blockdev setra read ahead setting

I've got some SSDs mounted up on /dev/sda1 and /dev/sdb1 on a SLES 11 SP2 server, and I was able to tweak the read ahead setting with blockdev --setra: sudo blockdev --setra 4096 /dev/sda sudo ...
3
votes
2answers
276 views

How can I find the actual (dd) size of a flash disk?

When I put a flash disk into a card reader and make an image with dd, I see the actual size of the disk, like 512483328 bytes in the following example: 1000944+0 records in 1000944+0 records out ...
3
votes
1answer
547 views

Finding all partitions with filesystems

I'm writing a script that will copy all of the files on a device to a directory. The problem is that some of the devices have multiple partitions and some of the partitions don't have filesystems to ...
3
votes
4answers
1k views

How to get size of a block special file?

I need to be able to determine the size of a block special file. For example, given /dev/sda, I need a command that will provide the size of the device. (By size I mean capacity, since this is a ...
3
votes
4answers
2k views

Comparison of raw block devices

Is there a utility (or some shell magic) that allows me to compare two block devices? Details: I have one large (0.5 TB) RAID device that I've backed up to a slightly larger SATA device using dd. ...
3
votes
2answers
1k views

Linux Mint: drives' map changing at reboot brings fstab error

I've set up fstab to auto mount media drives on a Linux Mint machine. The OS is installed on a IDE/ATA Disk while 3 SATA disks hold data to share. The BIOS has the ATA disk as first boot device. All ...
3
votes
2answers
49 views

How to tell if a SCSI device is removable?

In DMESG I see: [sdb] Attached SCSI removable disk How does Linux decide what is removable and not removable? Is there a way I can look up if a device is "removable" or not other than the log, for ...
3
votes
1answer
168 views

blockdev --setro doesn't work (for me at least)

I'm sure I don't understood how blockdev works. I going to expose the case here and hope some of you can help me. The case: I have mounted a flash drive and it was mapped to /dev/sdb1. Then I type ...
3
votes
1answer
414 views

Does the (source) device in a tmpfs type mount mean anything?

I just went into /etc/fstab (Linux) and changed my line for /tmp (on which a specific ext4 partition was previously mounted) to tmpfs. This was clearly a bit silly, but I wasn't thinking. Anyway, I ...
3
votes
2answers
256 views

raid 1/LVM at the level of directories (aka mknodding a directory)

I just experienced data loss, so I am interested in some form of data duplication. I was thinking of mdadm and companions to raid 1 through software. However, I just want a given, not too big ...
3
votes
1answer
60 views

bcache on md or md on bcache

bcache allows one or more fast disk drives such as flash-based solid state drives (SSDs) to act as a cache for one or more slower hard disk drives. If I understand correctly, an SSD* could be ...
3
votes
1answer
158 views

Low-level disk access in FreeBSD

I'm developing a utility that needs to do low-level random access of disks (read individual sectors). In Linux I accomplish this by accessing the corresponding block device (e.g. /dev/sda). However, ...
3
votes
1answer
1k views

Obtain device name and mount point if partition label is known

How to obtain the partition device name and mount point when the file system label is known? There are several possibilities: Linux File system label to device name The device name can be obtained ...
3
votes
2answers
947 views

How can I test whether a block device is read-only from /sys or /proc?

On a CentOS6 system I have /dev/block/sr0 (read only) and /dev/block/sda (read/write). How can I find out programmatically which devices are read-only? There is a ro file in there, but it's '0' for ...