A block device is a computer data storage device. It organizes data into fixed sized blocks that are typically 512 or 4096 bytes long. Data is indexed by a logical block address. Block storage devices are widely available, including spinning hard drives or solid-state devices. They may be used directly by applications or may have a filesystem or other data structure layered on top of them.
Questions tagged [block-device]
139 questions
78
votes
2 answers
How can I identify the request queue for a linux block device
I am working on this driver that connects the hard disk over the network. There is a bug that if I enable two or more hard disks on the computer, only the first one gets the partitions looked over and identified. The result is, if I have 1 partition…
ndasusers
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16
votes
3 answers
Retrieve correct Amazon attached EBS device from instance metadata endpoint
EDIT and TL;DR:
ubuntu@ip-172-31-19-77:~/.aws$ aws ec2 describe-instances | jq . | grep -i device
"BlockDeviceMappings": [],
"RootDeviceType": "ebs",
"RootDeviceName": "/dev/sda1",
"DeviceIndex": 0,
…
brainstorm
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13
votes
4 answers
USB Mass Storrage on File Level
The Challenge: I have an Linux hand-held device, which records data and stores it to the disc. It should exchange these data with a Windows application via USB. When this data is accessible by the user - e.g. via USB-mass-storage - it has to be…
Charly
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13
votes
2 answers
why is virtio-scsi much slower than virtio-blk in my experiment (over and ceph rbd image)?
Hi I recently did a experiment of virtio-scsi over rbd through qemu target (for its DISCARD/TRIM support), and compared the throughput and iops with that of a virtio-blk over rbd setup on the same machine, using fio in the guest. Turnout the…
Zhaohui Yang
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13
votes
3 answers
Getting live info from /dev/input
I am unsure if this is the correct place for this question. I am attempting to obtain the axis position values from a joystick /dev/input/js0 on my system. If I run jstest /dev/input/js0 it will give me live feedback on all buttons and axis…
Yamaha32088
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11
votes
3 answers
The bio structure in the Linux kernel
I am reading Linux Kernel Development by Robert Love. I don't understand this paragraph about the bio structure:
The basic container for block I/O within the kernel is the bio structure, which is defined in . This structure represents…
Vikram
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10
votes
3 answers
How to revert bcache device to regular device
I have a 20 gb SSD device on my laptop that i decided to try bcache on. It seemed to work, but for some time now, I've been getting an error on boot:
error on 0f3bbb55-6839-4ed6-8127-7976a969f726: corrupted btree at bucket 17571, block 483, 61 keys,…
Greg Michalec
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9
votes
2 answers
devicePolicyManager.lockNow() is not working for Motorola Tablets
public final static void lockDevice()
{
try
{
if (devicePolicyManager.isAdminActive(adminComponent))
{
devicePolicyManager.lockNow();
}
}
catch (final Exception…
PC.
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9
votes
2 answers
How do I read/write a block device?
How do I read/write a block device? I heard I read/write like a normal file so I setup a loop device by doing
sudo losetup /dev/loop4 ~/file
Then I ran the app on the file then the loop device
sudo ./a.out file
sudo ./a.out /dev/loop4
The file…
user34537
7
votes
2 answers
get device flags by device name
hope you can help me:
I'm trying to determine whether the device is removable or not, all i have is device name (/dev/sdc). Actually, I need to determine when the file on removable media or on local disk by full path of this file.
I've tryed to…
Makc
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7
votes
1 answer
Why is the kernel using the default block driver instead of my driver's code?
I wrote a block driver program which creates a dummy block device (sbd0). I registered all device operations for that block device: (Refer to include/linux/blkdev.h in 2.6.32 kernel source)
static struct block_device_operations sbd_ops = {
…
gangadhars
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6
votes
1 answer
Ceph CSI (rbd.csi.ceph.com) vs Ceph RBD (kubernetes.io/rbd)
I'm using kubernetes v1.16.10 with a Ceph 13.2.2 Mimic cluster for dynamic volume provisioning through ceph-csi.
But then I have found ceph-rbd
Ceph RBD…
jisnardo
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6
votes
1 answer
Kernel block device
I'm currently trying to implement a (not that ?) simple kernel block device driver.
I inspired mainly from the book Linux Device Drivers, 3rd Edition which is not totally up-to-date anymore as it was published in 2005.
Anyway the logic is still…
Arkaik
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6
votes
1 answer
Linux block device driver request ordering - RaW?
I am writing a Linux block device driver that receives requests via a function registered with blk_init_queue().
My hardware device reorders requests and as such to avoid read-after-write conflicts it is required to wait for the completion of…
hlitz
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6
votes
2 answers
Cygwin equivalent of Linux /dev/sda, /dev/sdb etc
On Linux, I can access a hard drive as /dev/sdX. This ignores any partition tables, file systems, etc, and just accesses the drive block by block. What is the equivalent in Cygwin? I already searched Google, but could not find anything that…
rsteward
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