Storage Flashcards by Paul Morino

Where are block device file stored?

/dev

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What is the first detected the first detected SATA, SAS, SCSI, or USB hard drive?

/dev/sda

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What is the second detected the first detected SATA, SAS, SCSI, or USB hard drive?

/dev/sdb

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What name is given to virtio-blk paravirtualized storage (VMs) device storage?

/dev/vda, /dev/vdb, /dev/vdc, etc.

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How do you recognize block devices on the file system?

ls -l /dev/sda1

Any entry with file type b is a block device.

brw-rw—-. 1 root disk 8, 1 Feb 22 08:00 /dev/sda1

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display an overview of local and remote file-system devices

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View the file systems on the host machine with all units converted to human-readable format

df -h

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View the disk usage report for the /usr/share directory

du /usr/share

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Which command provides an overview of the file-system mount points and the available free space in SI units?

df -H

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What is the naming pattern for ssd storage devices?

/dev/nvme0, /dev/nvme1, …

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What is the naming pattern for SD storage devices?

/dev/mmcblk0, /dev/mmcblk1, …

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list the details of a specified block device or of all the available devices

lsblk

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mount the /dev/vda4 partition on the /mnt/data mount point

mount /dev/vda4 /mnt/data

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Mount the file system by the file-system UUID.

mount UUID=”efd314d0-b56e-45db-bbb3-3f32ae98f652” /mnt/data

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Determine the UUID of a file system

lsblk -fp

lsblk -o NAME,UUID

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unmount a file system

umount /mnt/data

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identify which processes are preventing the file system from successfully unmounting

lsof /mnt/data

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How often is the locate db updated?

everyday

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force the locate database to update itself immediately?

updatedb

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Difference between locate and find

locate searches a pre-generated index and returns the results instantly (fast, index update delay).

find searches for files in real time by parsing the file-system hierarchy (slow, accurate).

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Example uses of locate

locate image
locate -i passwd
locate -n 5 file.txt

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search files with case-insensitive text that matches the messages string in their names in the root / directory,

find / -iname ‘messages’

search for files that the developer user owns

find -user developer

search for files that the developer group owns

find -group developer

search for files that the 1000 user ID owns

```find -uid 1000```

lists files that the root user owns and with the mail group

find / -user root -group mail

find file by permission

find /home -perm 764 find /home -perm u=rwx,g=rw,o=r

find file by permission while showing file details

find /home -perm 764 -ls

search for files for which the user has read permissions, OR the group has at least read permissions, OR others have at least write permission

find /home -perm /442 find /home -perm /u=r,g=r,o=w

search for files for which the user has at least write and execute permissions, AND the group has at least write permission, AND others have at least read permission

```find /home -perm -324``` ```find /home -perm -u=wx,g=w,o=r```

search for any file for which others have at least read access

find -perm -004 find -perm -o=r

search for files with a size of more than 10 gigabytes

find -size +10G

search for files with an exact size of 10 megabytes

find -size 10M

search for files with a size of less than 10 kilobytes

find -size -10k

search for all files with content that changed 120 minutes ago

find / -mmin 120

search for all files with content that changed more than 200 minutes ago

find / -mmin +200

lists files that changed less than 150 minutes ago

find / -mmin -150

Search for all directories in the /etc directory

find /etc -type d

Search for all soft links in the / directory

find / -type l

Search for all block devices in the /dev directory

find /dev -type b

Search for all regular files with more than one hard link

find / -type f -links +1

What are tools for disk and partition management?

1) Web console 2) ansible 3) fdisk 4) gdisk 5) parted

MBR

1) Legacy 2) 2 TiB disk and partition size limit 3) Max of 4 primary partitions 4) Suitable for old BIOS Firmware 5) 15 partitions max 6) 32 bits

GPT

1) Unified Extensible Firmware Interface (UEFI) firmware 2) eight zebibytes (ZiB) or eight billion tebibytes (TiB) size limit 3) 128 partitions max 4) 64 bits

Enable storage in cockpit

```dnf install cockpit-storaged```

standard partition editor on rhel

parted

what partitioning does parted support?

MBR and GPT

display the partition table on /dev/vda with parted

```parted /dev/vda print```

Configure new mbr disk with parted

```parted /dev/vdb mklabel msdos``` ```parted /dev/vdb mkpart primary 2048s 1001MB``` ```udevadm settle``` ```mkfs.xfs /dev/vdb1```

virtual memory

swap + RAM

format a partition for swap

mkswap /dev/vdb2

Activate swap on /dev/vdb2

swapon /dev/vdb2

swap file system type

linux-swap

Configure new GPT disk with parted

```parted /dev/vdb mklabel gpt``` ```parted /dev/vdb mkpart mydisk 2048s 1001MB``` ```udevadm settle``` ```mkfs.xfs /dev/vdb1```