I am new to Linux and I am trying to set the readahead value as told by this article: https://www.ca.com/us/services-support/ca-support/ca-support-online/knowledge-base-articles.tec616116.html
When I try the command:
blockdev --setra 2048 /dev/sdb
Nothing happens. I've also tried with sudo. When I run blockreport I always get this report:
So I also tried blockdev --setra 2048 /dev/sr0 since that seems to be the device name, but then I get the error "device sr0 not found".
Do you know what I am doing wrong when trying to set the readahead value?
A restart of the system was required to take effect.
/dev/sr0 is a device on the scsi controller. /dev/cdrom is a symlink to either /dev/sr0 or /dev/hdc or whichever block device is appropriate.
I think you are trying to change RA for which the actual medium is not present.
Related
I'm looking for some hints while troubleshooting missing CDROM device.
The problem is, missing configuration option for my custom kernel (linux-5.4.78).
My current .config has:
CONFIG_CDROM=y
CONFIG_BLK_DEV_SR=y
CONFIG_VHOST_SCSI=y
CONFIG_BLK_SCSI_REQUEST=y
CONFIG_SCSI_MOD=y
CONFIG_SCSI=y
CONFIG_SCSI_DMA=y
CONFIG_SCSI_NETLINK=y
CONFIG_SCSI_PROC_FS=y
CONFIG_SCSI_SPI_ATTRS=y
CONFIG_SCSI_FC_ATTRS=y
CONFIG_SCSI_ISCSI_ATTRS=y
CONFIG_SCSI_SAS_ATTRS=y
CONFIG_SCSI_SAS_LIBSAS=y
CONFIG_SCSI_SAS_HOST_SMP=y
CONFIG_SCSI_LOWLEVEL=y
CONFIG_ISCSI_TCP=y
CONFIG_ISCSI_BOOT_SYSFS=y
CONFIG_SCSI_CXGB3_ISCSI=y
CONFIG_SCSI_CXGB4_ISCSI=y
CONFIG_SCSI_BNX2_ISCSI=y
CONFIG_BE2ISCSI=y
CONFIG_SCSI_HPSA=y
CONFIG_SCSI_3W_9XXX=y
CONFIG_SCSI_3W_SAS=y
CONFIG_SCSI_ACARD=y
CONFIG_SCSI_AACRAID=y
CONFIG_SCSI_AIC7XXX=y
CONFIG_SCSI_AIC79XX=y
CONFIG_SCSI_AIC94XX=y
CONFIG_SCSI_HISI_SAS=y
CONFIG_SCSI_HISI_SAS_PCI=y
CONFIG_SCSI_MVSAS=y
CONFIG_SCSI_MVSAS_TASKLET=y
CONFIG_SCSI_MVUMI=y
CONFIG_SCSI_DPT_I2O=y
CONFIG_SCSI_ADVANSYS=y
CONFIG_SCSI_ARCMSR=y
CONFIG_SCSI_ESAS2R=y
CONFIG_SCSI_MPT3SAS=y
CONFIG_SCSI_MPT2SAS=y
CONFIG_SCSI_SMARTPQI=y
CONFIG_SCSI_UFSHCD=y
CONFIG_SCSI_UFSHCD_PCI=y
CONFIG_SCSI_UFSHCD_PLATFORM=y
CONFIG_SCSI_UFS_CDNS_PLATFORM=y
CONFIG_SCSI_UFS_HISI=y
CONFIG_SCSI_UFS_BSG=y
CONFIG_SCSI_HPTIOP=y
CONFIG_SCSI_BUSLOGIC=y
CONFIG_SCSI_FLASHPOINT=y
CONFIG_SCSI_MYRB=y
CONFIG_SCSI_MYRS=y
CONFIG_VMWARE_PVSCSI=y
CONFIG_SCSI_SNIC=y
CONFIG_SCSI_DMX3191D=y
CONFIG_SCSI_FDOMAIN=y
CONFIG_SCSI_FDOMAIN_PCI=y
CONFIG_SCSI_GDTH=y
CONFIG_SCSI_ISCI=y
CONFIG_SCSI_IPS=y
CONFIG_SCSI_INITIO=y
CONFIG_SCSI_INIA100=y
CONFIG_SCSI_PPA=y
CONFIG_SCSI_IMM=y
CONFIG_SCSI_STEX=y
CONFIG_SCSI_SYM53C8XX_2=y
CONFIG_SCSI_SYM53C8XX_MMIO=y
CONFIG_SCSI_IPR=y
CONFIG_SCSI_IPR_TRACE=y
CONFIG_SCSI_IPR_DUMP=y
CONFIG_SCSI_QLOGIC_1280=y
CONFIG_SCSI_QLA_FC=y
CONFIG_SCSI_QLA_ISCSI=y
CONFIG_SCSI_LPFC=y
CONFIG_SCSI_DC395x=y
CONFIG_SCSI_AM53C974=y
CONFIG_SCSI_WD719X=y
CONFIG_SCSI_PMCRAID=y
CONFIG_SCSI_PM8001=y
CONFIG_SCSI_BFA_FC=y
CONFIG_SCSI_VIRTIO=y
CONFIG_SCSI_CHELSIO_FCOE=y
CONFIG_SCSI_LOWLEVEL_PCMCIA=y
CONFIG_SCSI_DH=y
CONFIG_SCSI_DH_RDAC=y
CONFIG_SCSI_DH_HP_SW=y
CONFIG_SCSI_DH_EMC=y
CONFIG_SCSI_DH_ALUA=y
CONFIG_ISCSI_TARGET=y
CONFIG_ISCSI_TARGET_CXGB4=y
CONFIG_QED_ISCSI=y
I'm expecting to see /dev/sr0. It's not there. dmesg is mute about sr0.
However, I'm able to see it using stock kernel and I've identified it was bring by BLK_DEV_SR on my target:
# ls -l /dev/sr0
brw-rw---- 1 root optical 11,0 Apr 21 15:02 /dev/sr0
# readlink /sys/dev/block/11\:0/device/driver
../../../../../../../../../../../../bus/scsi/driver/sr
I'd appreciate any help.
If your custom linux has udev, try udevadm monitor.
When you eject or insert a cd, you should see a change event on the terminal with the device path.
Also it's normally standard for a cdrom drive, no matter the actual device path, to be forwarded to /media/cdrom
'uname -a' on my machine gives:
Linux ct-lt-966 4.9.0-8-amd64 #1 SMP Debian 4.9.144-3.1 (2019-02-19) x86_64 GNU/Linux
Currently the filesystem of my USB is MS-DOS 'FAT32' which has a ~4.5 GB maximum size for individual files. I want to change this filesystem to something else, which does not have a limit. (I am trying to put a 35GB file onto a 64GB USB but I believe most USB filesystems do not limit the size of individual files).
I have not found it clear what choices of USB filesystem that I have. I tried to change the filesystem to 'NTFS', but I could not install or locate 'mkfs.ntfs' or even 'ntfsprogs'. (I also tried installing with 'pacman' and 'yum' but apparently 'pacman' requires an aarch architecture and I could not get access to 'yum-config-manager' in order to enable any repos).
So to conclude, with my minimal prowess I am just looking for any way to change the filesystem of my 64GB USB to anything which will accept a 35GB file from my machine.
Thanks
Edit 1: Just planning to use the USB on this Linux machine, not Windows.
If there's nothing on the stick you want, or it's safe to delete it then basically:
delete the current FAT32 partition from the stick
add a new partition, utilising the full size of the device
create an ext4 filesystem on the new partition
PLEASE BE CAREFUL WITH THIS PROCESS: selecting the wrong device can obliterate a disk you needed such as a $HOME or your root OS
All the following is from memory and untested: I don't have a USB stick available right now to test fully.
Start by plugging in the stick while tailing the syslog in a console and see where it gets mounted (hopefully it automounts which it should if it's a desktop based Linux you're running. Possibly not if it's a server)..
sudo tail -f /var/log/syslog
(it might be /var/log/messages depending on distro)
then plug the stick. syslog should show it being allocated a device and a mount point. A file manager window may open depending on your config if you are in a GUI. For example, you might see it being loaded on /dev/sdc1 and mounted at /media/<yourusername>/USBKEY or something.
Confirm by running lsblk and note the device for the key, i.e.
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 167.7G 0 disk
├─sda1 8:1 0 69.9G 0 part /
└─sda2 8:2 0 97.9G 0 part /home
sdb 8:16 0 149.1G 0 disk
└─sdb1 8:17 0 149.1G 0 part /mnt/snapshots
sdc 8:32 0 931.5G 0 disk
└─sdc1 8:33 0 931.5G 0 part /storage
sdd 8:48 0 465.8G 0 disk
└─sdd1 8:49 0 465.8G 0 part /mnt/backup
sr0 11:0 1 1024M 0 rom
Unmount the stick (if it mounted) but leave it plugged in. Assuming again your device is at /dev/sdc1...
umount /dev/sdc1
Now run cfdisk in a terminal if you have it (friendlier) or fdisk if not, passing it the device related to your USB stick, without the partition number.
man cfdisk
sudo cfdisk /dev/sdc
This should show the current FAT32 partition. Delete it, then create a new partition of type 'Linux', following the defaults for start and end blocks which will be suggested in such a way as to fill the available space.
When done, select the option to Write the changes. Again, DOUBLE AND TRIPLE CHECK you have the right device or you will blow away your main disk probably.
Once the changes are written, you can create the ext4 file system;
sudo mkfs.ext4 /dev/sdc1
And after it completes, you should be able to re-plug your stick and find that it remounts, this time with a file system that can take your large files.
This isn't the only way to achieve this, but it's probably the least fiddly. For the sake of repetition, don't make a mistake with the device identifiers. If you're unsure, ask.
I have a hard drive with ubuntu 14 installed. The whole disk is encrypted. My default users home directory is encrypted as well. Lately, after a system crash, I am presented with a busybox (initramfs) on startup. When I chose to start in recovery mode, I can grasp several error messages like " ... Failed to read block at offset xyz ...".
I searched and found this Q&A: Boot drops to a (initramfs) prompts/busybox
I booted from a CD and followed the instructions. However I am only able to do ...
sudo dumpe2fs /dev/sda1
... and then continue to check and repair superblocks on /dev/sda1 .
If I try ...
sudo dumpe2fs /dev/sda2
... i get the following error message:
dumpe2fs: Attempted to read block from filesystem resulted
in short read while trying to open /dev/sda2
Couldn't find valid filesystem superblock.
gparted shows the partitioning and file systems of the drive as follows:
partition file system size used unused flags
-------------------------------------------------------------
/dev/sda1 ext2 243M 210M 32M boot
/dev/sda2 extended 465G - - -
/dev/sda5!!crypt-luks 465G - - -
unallocated unallocated 1M - - -
The warning (!!) at sda5 says "Linux Unified Key Setup encryption is not yet supported".
If I try ...
sudo dumpe2fs /dev/sda5
... it returns this error message:
dumpe2fs: Bad magic number in super-block while trying to open /dev/sda5
Couldn't find valid filesystem superblock.
Mounting and rw-accessing sda1 works without error.
Any clues what is the cause and how i can repair, mount and decrypt the filesystem to boot normaly or at least to recover the data?
The given solution has missed some commands that you need to decrypt the file system and access it. Here's the full solution
Boot from Ubuntu USB
cryptsetup luksOpen /dev/rawdevice somename
sck /dev/mapper/somename
Get backup superblock:
sudo dumpe2fs /dev/mapper/ubuntu--vg-root | grep superblock
Fix:
sudo fsck -b 32768 /dev/mapper/ubuntu--vg-root -y
Verify:
mkdir /a
sudo mount /dev/mapper/ubuntu--vg-root /a
This worked for me:
Boot from Ubuntu USB
get backup superblock:
sudo dumpe2fs /dev/mapper/ubuntu--vg-root | grep superblock
fix:
sudo fsck -b 32768 /dev/mapper/ubuntu--vg-root -y
verify
mkdir /a
sudo mount /dev/mapper/ubuntu--vg-root /a
I used following links as source:
https://askubuntu.com/questions/137655/boot-drops-to-a-initramfs-prompts-busybox
https://serverfault.com/questions/375090/using-fsck-to-check-and-repair-luks-encrypted-disk
I'm trying to recover some data from a hard drive extracted from a broken laptop, and I'm having problems mounting the disk to my current system (Linux Mint). The hard disk I'm recovering from ran Debian. Simply, I'm confused as to how I can mount the hard drive to access the files, however it's not as simple as any other mount I've done. The following details struggles and information I've encountered.
I get the following outputs when trying to mount the hard drive with different file-system tags. I should add that the file-system type isn't automatically detected when using auto, and "sdb" is definitely the correct address for the disk (taken it from dmesg).
$ mount /dev/sdb /mnt/usb -t ntfs
NTFS signature is missing.
Failed to mount '/dev/sdb': Invalid argument
The device '/dev/sdb' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?
The following returns the same message when all other common file-system tags are used:
$ sudo mount /dev/sdb usb -t ext2
mount: wrong fs type, bad option, bad superblock on /dev/sdb,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
The results from these commands led me to believe that there was an issue with the hard disk and it's partitions, however fdisk proved that it's partition's do seem to be valid and correct:
$ sudo fdisk /dev/sdb -l
Disk /dev/sdb: 250.1 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders, total 488397168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0002da94
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 475920383 237959168 83 Linux
/dev/sdb2 475922430 488396799 6237185 5 Extended
/dev/sdb5 475922432 488396799 6237184 82 Linux swap / Solaris
I then decided to try verify the file-system type of the hard drive, which seems to be "devtmpfs", which I got from the following command using df:
$ df /dev/sdb -T
Filesystem Type 1K-blocks Used Available Use% Mounted on
udev devtmpfs 1014764 4 1014760 1% /dev
And so finally, I mount the hard drive using -t devtmpfs, which is successful in mounting however I'm left with a confusing file system very unlike from what I would expect from what was a standard debian set up.
It contains file folders such as "block","bus","char","disk","dri","mapper"... and files like "sda1","sdb","sdb1","tty","vcs".
I'm totally stumped as to how I should progress, and I'm pretty convinced the hard disk isn't broken and that I'm just mounting it incorrectly. How can I successfully mount the disk so I can access my files? Any help would be greatly appreciated.
Ok, you are trying to mount the entire disk instead of individual partitions, which is why you are getting the error. In short the command you need is:
mount /dev/sdb1 /mnt/usb
The file /dev/sdb references the entire disk as a block file. This includes the partition table at the start, which is why it can't find a filesystem. The file /dev/sdb1 references the first partition, which is where your filesystem will be. From the looks of your fdisk output, this is not an ntfs partition since this is a Windows filesystem and the partition is marked as Linux (most likely you will have ext4 unless you specifically set up something different).
To add a quick explanation of devtmpfs, this is a special filesystem which contains these block files which are specified by udev. You can google both for more information, but by now I'm sure you now know its not what you are looking for.
I formatted a partition using mkfs.xfs /dev/mydevice in Ubuntu and then I mounted it using /etc/fstab. When I type mount, it tells me that my device is mounted as ext3.
Output of mount:
/dev/mydevice on /mnt/mymount type ext3 (rw,_netdev)
First question: How do I know if it's xfs or ext3? What am I missing?
Second question: If it's xfs, how do I know if it's xfs-256 or xfs-512?
loading the device in a utility like gparted tells you FS types.
for fstab file it's enough, I think, to say only xfs.