A data storage device that supports reading/writing data in fixed-size blocks, sectors, or clusters.

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1answer
32 views

How to prevent /sda /sdb changes between boots?

I am going to install Gentoo Linux onto an old hardware, which motherboard is having both IDE and SATA hard drives. I have two IDE and one SATA hard drives connected, and plan to do RAID on them. ...
1
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0answers
8 views

Changing readahead value using blockdev command

I am trying to modify read ahead value using blockdev. When I issue this command blockdev --setra xxx /dev/sda - it changes the readahead value of the entire partition in that device, which is fine. ...
1
vote
1answer
17 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 ...
7
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1answer
99 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 ...
2
votes
2answers
48 views

No space left on device on CentOS7

My machine which OS is CentOS7 have to backup 50G data into MySQL. But, there is no space left on the device. But there are many spaces on /home. How can I make user that there are enough space for ...
1
vote
0answers
9 views

Files backing loop devices opened without O_EXCL

Loop devices are the primary way (and perhaps the only way) to treat normal files as block devices in Linux. It's strange that backing files aren't protected by O_EXCL flag. Why is that? Why nobody ...
3
votes
1answer
36 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
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1answer
25 views

How can I access optical drive status information?

I can obtain the status of a connected display with: cat /sys/class/drm/card0-HDMI-A-1/status Is there something analogous for optical drives? I looked around in /sys/ but couldn't find anything that ...
0
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0answers
10 views

is `blockdev --flushbufs /dev/mmcblk0p1"` blocking call?

I am using blockdev --flushbufs /dev/mmcblk0p1 in onf the shell script and would like to know if this command doing blocking call or not? I see it from man page that it is ioctl call to the block ...
0
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2answers
34 views

CPU: 13 PID: 15452 Comm: ssd_blk/0 Tainted: G B I E 3.19.0+ #1

I developed a module which works as an emulator for a block device. When I write into the block device, I get this in dmesg and the module crashes. I cannot get any hint about what is going on? ...
1
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3answers
63 views

How could Linux use 'sda' device file when it hasn't been installed?

I am installing CentOS Linux distribution on a fresh new machine. Just for learning. I am new to Linux. At the partition step, CentOS tells me that it has detected a sda HD in my machine and I should ...
1
vote
1answer
37 views

Block device disappears after suspend-resume

After few suspend/resume cycles one of my hdd disappears from the list of devices, here is part of dmesg output that seems to be related to issue: [ 450.005310] sd 5:0:0:0: [sdc] Starting disk [ ...
0
votes
0answers
8 views

How “ata_for_each_link” and “ata_for_each_dev” macros works in linux kernel?

I am trying to understanding the SATA device enumeration sequence from the ata_piix.c Host controller driver which resides at /driver/ata/ata_piix.c in linux kernel. During understanding the flow,a ...
37
votes
4answers
10k 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 ...
1
vote
2answers
127 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
vote
0answers
20 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 ...
12
votes
5answers
31k 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 ...
19
votes
4answers
6k 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 ...
4
votes
4answers
8k 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 ...
1
vote
0answers
36 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 ...
63
votes
6answers
56k 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 ...
2
votes
1answer
46 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
votes
0answers
63 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 ...
1
vote
1answer
94 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 ...
2
votes
1answer
90 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
votes
2answers
75 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. ...
6
votes
6answers
5k 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. ...
1
vote
1answer
167 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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0answers
12 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
143 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 ...
8
votes
4answers
4k 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?
0
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2answers
577 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 ...
4
votes
5answers
5k 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 ...
4
votes
1answer
27 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
votes
2answers
665 views

KVM linux guest, 2nd HDD, LVM partition or whole disk

I've got a RAID 10 arrays on a couple of KVM host machines. The RAID 10 array is one big VG. I usually create a small LV for guest disk image storage then the rest of the VG I carve out as LVs to add ...
3
votes
0answers
31 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
vote
1answer
33 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? ...
3
votes
3answers
5k views

how to set block size using blockdev command

Anyone can provide me any test case for the below command: blockdev --setbsz BYTES to set/change the block size. I have tried like below but no luck. $ blockdev --setbsz 2048 /dev/sda5 blockdev: ...
2
votes
5answers
23k views

SD card corrupt and stuck at 32MB, any way to fix it?

Using the Linux area since I'm using Linux apps and utilities. My phone crashed (several times) and managed to corrupt my microSD card. It no longer appears to have partitions and shows as 32MB ...
0
votes
1answer
44 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
vote
2answers
139 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 ...
1
vote
0answers
220 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
vote
2answers
597 views

Could not mount UBIFS on SD card

I guess this is not a big problem, still I can't see what's the matter. I'm building Images for an Embedded Linux (2.6.39) ARM9 System with Buildroot 2013.11, which is booting from an SD card. I was ...
13
votes
7answers
4k 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 ...
1
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2answers
129 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
384 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 ...
0
votes
2answers
263 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 ...
3
votes
0answers
294 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
votes
0answers
29 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? ...
21
votes
8answers
37k 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 ...