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2answers
73 views

What is a block device? [duplicate]

I know many examples of block devices (HDD's, SSD's, files, ...), but I haven't heard a simple definition of it. Especially since files are apparently included in the definition I feel a bit ...
1
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0answers
17 views

Tar waiting a long time at end of block device

I had some trouble getting Linux installed to a particular netbook and had to restart it from scratch multiple times. Re-typing the same commands to set up networking and bootstrap the install was ...
1
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0answers
21 views

Storage device trouble: IO errors but no bad sectors?

I have a lightly used spinning metal drive (internal) with some VMs on it. I'm running into IO errors while running a VM and upon closer examination I have found a virtual disk file that is reporting ...
2
votes
1answer
20 views

Transfer content of LVM block device ensuring consistency - LVM snapshot?

I need to create off-site full backups of an LVM block device. Thinking the old dd over SSH method. To ensure I have a consistent backup, should I create an LVM snapshot first? So new changed blocks ...
3
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0answers
50 views

How to cache block devices (for device mapper)?

problem / observed effect It seems that the page cache ignores block devices which are not opened. And worse: Reads from device mapper (DM) devices which use a cached device are not cached at all ...
2
votes
1answer
61 views

Difference between sd0/sda, hd0/hda

From what I understand, hdx is naming convention for IDE (PATA) drive, sdx is for SCSI (SATA) drive. Sometimes I see sd0 and sda, similary hd0/hda. What are their differences ? When would we use ...
4
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2answers
69 views

In which thread does block driver issue commands to block device?

I'm currently reading "Understanding The Linux Kernel" book, as I've understood block I/O request order is like this; user space call => vfs call => I/O scheduler call => block device driver call. ...
1
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1answer
72 views

dd, cat & openssl: block size & buffer size

Here it says that when using dd through dm-crypt to overwrite a block device, only the default dd block size should be used because dm-crypt's block size is the same (512 bytes), and increasing dd's ...
1
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1answer
51 views

How to find the driver (module) associated with SATA device on Linux?

For one of my applications, I have to understand the the SATA device driver flow. As per my understanding, SATA device driver should be there in the Linux kernel tree. I have referred how to find the ...
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0answers
7 views

Getting mmc_block to display more than 8 partitions

When you format an SD card or a USB drive with the Chromebook Recovery Utility, it creates twelve partitions. It also leaves the rest of the memory unallocated. I want to be able to use this space as ...
4
votes
1answer
101 views

How does cat 'know' the optimum block size to use?

From reading this, it seems that when copying data to a different hard drive, cat automatically uses the optimum block size (or very near it). I wonder how it determines the optimum block size, and ...
4
votes
1answer
20 views

Get label of Linux storage partition device file

Given the partition device file /dev/sdh1, I need to find out the label of this device. dmesg doesn't mention its label while GParted reveals that it is called H2N_SD: I need to build a way to be ...
2
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0answers
26 views

Enumerate valid values for mknod

I have access to an embedded device which has a bunch of block/char files under /dev. However, this is not a satisfying description of the hardware, because since the firmware is shared with small ...
1
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1answer
29 views

How do I store the data in disk directly in kernel module? [closed]

I capture the TCP packet in function of netif_receive_skb , I want to store the playload of TCP packet. we can't read/write the file in kernel module, so store in disk directly maybe a way? ...
0
votes
1answer
39 views

How do I detect used harddrive space on a block device?

I want to look at a raw block device (as in /dev/sda) and know how much space is being used on the drive. I don't know what type of file system is on the harddrive, nor do I have any way of figuring ...
1
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0answers
112 views

CentOS 7 - Forcing a disk to be /dev/sda

I've been wrestling with this problem for awhile now, and I've hit a wall and need help. In my system, I have 1 drive connected to a SATA port, an SSD. CentOS 7 is installed to this disk. Also in ...
1
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2answers
101 views

Is UUID really unique? why can we assign multiple UUIDs to single slice of disk

All the web content and its acronym explains it as Uniquely identifier. But when i try to create another device, lets say swap in my case and assign the UUID, i am able to assign many UUIDs to single ...
4
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1answer
221 views

How does Linux handle block devices?

Today I learned that FreeBSD removed support for block devices entirely. While reading their rational for the decision I came across this: Block devices are disk devices for which the kernel ...
3
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0answers
205 views

How to change block device names, e.g. /dev/sdc to /dev/sdb?

Example of why this might be desired: I connect a block device, which shows up as /dev/sdb, and mount it. Later that device gets removed without being unmounted. The block device is reconnected, but ...
0
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0answers
26 views

RHEL7 : Freeing memory allocated for Block IO i.e. bio -> bio_destructor

I want to know HOW memory allocated for BIO gets free specific to RHEL 7. I think, in RHEL 7 , bio->destructor field is removed from the bio structure. So, how exactly the memory will be freed? ...
1
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2answers
95 views

How to get disk name that contains a specific partition

If I know that a partition is for example /dev/sda1 how can I get the disk name (/dev/sda in this case) that contains the partition ? The output should be only a path to disk (like /dev/sda). It ...
8
votes
3answers
187 views

Will a usb key have the same name everytime I mount it?

I have a usb key which will be used to save data on it daily, via a bash script. I managed to mount it for a specific user to be able to write folders in it using the command mount /dev/sdc1 ...
3
votes
3answers
229 views

Does dd copy everything, including all metadata and all “empty” blocks

Suddenly something was messed up with my partitions, or just one partition. I have a default Ubuntu installation, on a Kingston SSD, with the root file system encrypted with LUKS, (using AES I think). ...
3
votes
1answer
50 views

Is there any way to prevent a bad drive from disappearing from /dev?

I'm trying to recover a partition on a bad drive with ddrescue. I run: $ sudo ddrescue -r -1 -v /dev/sdd3 OUT.img dd_rescue_logfile and it seems to do great for a while, but after about an hour, ...
0
votes
0answers
223 views

DRBD device names and numbers

I am trying to deploy a DRBD setup. I am using two virtual machines running CentOS 6.6. It is quite unclear to me how should the drbd configuration file should look like. I am using the following ...
1
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0answers
59 views

List partition type GUID's for all disks from command line?

I need to list the partition type GUID's from the command line. Note: This is not the same as the partition UUID. Basically I'm needing to search for all disks that have the Ceph OSD type GUID: ...
2
votes
0answers
72 views

How to use blktrace to monitor the eMMC Flash access pattern?

I'm trying to simulate a FTL(Flash Translation Layer) algorithm and evaluate its performance. What I need is a trace file of a flash access(containing information about block and page access). I'm ...
1
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0answers
28 views

Remove orphaned rados block device

I'm testing ceph at the moment. Today I decided to start over with my cluster and deleted the old one to setup a new one. I forgot to unmap and delete a mapped rbd device from another host. Now I see ...
0
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0answers
38 views

one nautilus device went missing, why? and how to fix?

nautilus devices are provided by /usr/lib/gvfs/gvfs-udisks2-volume-monitor, I've already restarted it but one device is still missing. I also tried strace on it, but it only outputs info about mounted ...
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0answers
353 views

Map a Linux VM's block device to its vmdk file on the vmware datastore

For development and staging purposes, I must frequently create clones of individual virtual harddisks (vmdk container) and move/deploy them into some other system. While I have been able to hack a ...
0
votes
2answers
372 views

How to benchmark memory in an embedded linux device?

Is there a generic utility to benchmark external memory device (eMMC, DDR) throughput on an embedded device (e.g. raspberry pi)? memtester, bonnie, bonnie++, memtest, dd? I've been running into ...
0
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2answers
39 views

Can we predict the next registered SCSI mass storage device name

I need to anticipate the device name (sdX) that the next mass storage device (sda, sdb, sdc, …) will receive from the SCSI driver. If I remove one device and connect another one, I noticed that the ...
0
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1answer
92 views

Force Filesystem Reread / Remount

Is it possible to force a complete re-read of a mounted filesystem (EXT4) from disk in a blocking manner? I have a potential situation where independent and external hardware can modify a filesystem ...
0
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0answers
23 views

How to obtain block device label [duplicate]

I have a tricky problem. I have a block device connected to SLES11, it is present in /proc/partitions but it is not mounted (not present in /proc/mounts). From C code I want to find the block device ...
1
vote
1answer
356 views

Can you scp a device file?

My flash is partitioned as /dev/mtd0 /dev/mtd1 etc....And I want to scp one of the partitions over to my pc so I can analyze it with a hex editor, but everytime I try to copy it with scp I get -not a ...
0
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2answers
218 views

M17: Trying to mount Windows 10 .iso onto partition via terminal, getting “block device ? is write-protected, mounting read-only”. Can I get a help?"

I have Linux Mint 17.1 and am trying to dual boot Windows 10 Technical Preview OR install it on my other hard drive. Extra easy damage-control for you guys- I do not care if I lose any data, as long ...
0
votes
2answers
38 views

Cloning a drive larger than your own

I made this nice backup system to turn drives into vdi's and put them on our network share. Then the next day my boss walks in with 20 new machines to replace our old ones, they have 2TB drives. How ...
4
votes
2answers
410 views

How to get UUID of filesystem given a path?

I am handed a path of a directory or a file. Which utility/shell script will reliably give me the UUID of the file system on which is this directory/file located? By UUID of file system I mean the ...
3
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1answer
99 views

Find/replace on block device?

Let's say I have an unmounted block device /dev/sda, and I want to replace all instances of MyPassWord with XXXXXXXXXX. (Hopefully my goal is obvious.) What's the easiest way to do this?
3
votes
1answer
1k views

Write an image to a flash drive under OpenBSD

Under Linux, I can simply do a: dd if=ubuntu-14.04.1-desktop-amd64.iso of=/dev/sdb and boot up the /dev/sdb which is a device for a flash drive. It finishes in 263 seconds. But: If I boot up an ...
13
votes
1answer
871 views

Why does Linux use SCSI drivers for non-SCSI devices? [duplicate]

Looking at what block device commands like lsblk or blkid return it seems that linux HDD support SCSI drivers regardless of the type of the devices, like a USB flash driver that is presented as ...
4
votes
4answers
6k views

List all devices connected, FreeBSD

What's the FreeBSD variant of Linux's lsblk and blkid? I want something that provides the same sort of information as lsblk does in the example below: NAME MAJ:MIN RM SIZE RO TYPE ...
4
votes
1answer
208 views

Create a write-cache loop device for a much larger block device

So, long story short. * I had a 5.5TB RAID5 array with a HP controller. * HP uses a really, really painful RAID5 algorithm (ref: Delayed Parity) * I wrote a new block driver that translates requests ...
1
vote
1answer
130 views

arch linux recognizes the partitions and hard disks wrongly

My arch Linux system does not recognize neither the partition nor the hard disk in which it is installed. it is installed on /dev/sdb1 but it recognizes that as /dev/sdc1 and the initialization goes ...
9
votes
3answers
270 views

How can `dd` be used to right-shift data blocks?

Consider a 100MB raw block device as a simple example. That is 204800 blocks of 512 bytes each for a total of 102760448 bytes. The challenge is to shift the first 98MB (200704 blocks) so there is a ...
1
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0answers
65 views

How can I limit or delay the write speed to specify directory? [closed]

I want to limit the write speed and limit to specify directory. Make this directory flakey. Make this directory error for can't write data to it. I have user dmsetup to create the device mapper with ...
1
vote
1answer
63 views

Chunked transfer contents of block device over bad network

/dev/sda is the only disk on system. I want to save it to a raw image on another server. I can't do it in one shot, because network disconnects often. Is it possible with e.g. torrent?
3
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2answers
4k views

Mount an ISO virtually using /dev/sr0 device

I'm doing a study about how CD-ROM can be mounted virtually and all I could find out was mounting using loop devices. mount -o loop disk1.iso /mount-point This is fairly easy. I understand that ...
6
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2answers
808 views

virtual block device

I'm not sure what I should be googling or if FUSE does this (I suspect not). I'd like to create a virtual block device for which all forms of access, for example reads and writes, go directly to my ...
1
vote
1answer
45 views

DVD giving inconsistent size informatin

I have a (read-only, commercial, dual-layer) DVD which I’m trying to create a backup copy of on my computer (because DVDs can be damaged). However, when I try to determine the size of the disc, I get ...