disk operation
|-----------------------disk---------------------|
|-----partition------|---------partition---------|
|-----filesystem-----|---------filesystem--------|
ref: https://stackoverflow.com/questions/24429949/device-vs-partition-vs-file-system-vs-volume-how-do-these-concepts-relate-to-ea
Partition Table Type
A data structure that provides basic information for the OS about the partition of the hard disk.
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MBR: Master Boot Record.
Used with the legacy BIOS firmware.
An older standard. (only support < 2T disk)
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GPT: GUID Partition Table
Used with the EFI firmware. (not compatible with BIOS)
Current default.
GPT contains a fake MBR at the beginning of its space. This MBR shows the drive as being a single MBR partition to cope with tools which do not recognize GPT.
Filesystem
A way of storing data inside the partitions.
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EXT / EXT2 / EXT3
older version of EXT.
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EXT4
current default for Linux, Android.
support both Windows and Linux. support < 1EB = 2^20 TB.
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FAT
much older, for Windows. FAT16 < 4GB, FAT32 < 32 GB.
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NTFS
current default for Windows.
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VFAT
support both Windows and Linux, usually for swap and recovery.
check disk state and mount point
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fdisk: check all physically loaded disks$ sudo fdisk -l Disk /dev/sda: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: gpt Disk identifier: 943FD3C6-B398-4D2E-8A66-58991158B3A2 Device Start End Sectors Size Type /dev/sda1 2048 1050623 1048576 512M EFI System /dev/sda2 1050624 3905028095 3903977472 1.8T Linux filesystem /dev/sda3 3905028096 3907028991 2000896 977M Linux swap Disk /dev/sdb: 953.9 GiB, 1024209543168 bytes, 2000409264 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 /dev/sdc: 931.5 GiB, 1000204886016 bytes, 1953525168 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 /dev/sdd: 931.5 GiB, 1000204886016 bytes, 1953525168 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytesLinux Filesystem is where the root
/is mounted.EFI System (Extensible Firmware Interface) is used to boot the system. (UEFI firmware loads the files on the EFI System)
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mountcheck the mount$ mount sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) udev on /dev type devtmpfs (rw,nosuid,relatime,size=131978096k,nr_inodes=32994524,mode=755) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=26402968k,mode=755) /dev/sda2 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k) tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) efivarfs on /sys/firmware/efi/efivars type efivarfs (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/rdma type cgroup (rw,nosuid,nodev,noexec,relatime,rdma) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio) cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio) cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset) cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event) cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory) cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=35,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=55306) debugfs on /sys/kernel/debug type debugfs (rw,relatime) mqueue on /dev/mqueue type mqueue (rw,relatime) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,pagesize=2M) fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime) configfs on /sys/kernel/config type configfs (rw,relatime) /dev/sdb on /data2 type ext4 (rw,relatime,data=ordered) /dev/sdc on /data3 type ext4 (rw,relatime,data=ordered) /dev/sdd on /data4 type ext4 (rw,relatime,data=ordered) /dev/sda1 on /boot/efi type vfat (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro) tmpfs on /run/user/1002 type tmpfs (rw,nosuid,nodev,relatime,size=26402968k,mode=700,uid=1002,gid=1002)Note the physical disk lines:
/dev/sda2 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered) /dev/sdb on /data2 type ext4 (rw,relatime,data=ordered) /dev/sdc on /data3 type ext4 (rw,relatime,data=ordered) /dev/sdd on /data4 type ext4 (rw,relatime,data=ordered) /dev/sda1 on /boot/efi type vfat
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dfsimplified version.$ df -h Filesystem Size Used Avail Use% Mounted on udev 126G 0 126G 0% /dev tmpfs 26G 19M 26G 1% /run /dev/sda2 1.8T 1.5T 214G 88% / tmpfs 126G 0 126G 0% /dev/shm tmpfs 5.0M 4.0K 5.0M 1% /run/lock tmpfs 126G 0 126G 0% /sys/fs/cgroup /dev/sdb 939G 562G 330G 64% /data2 /dev/sdc 917G 729G 142G 84% /data3 /dev/sdd 917G 72M 871G 1% /data4 /dev/sda1 511M 3.7M 508M 1% /boot/efi tmpfs 26G 0 26G 0% /run/user/1002
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lsblkanother simplified version.$ sudo lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sdd 8:48 0 931.5G 0 disk /data4 sdb 8:16 0 953.9G 0 disk /data2 sdc 8:32 0 931.5G 0 disk /data3 sda 8:0 0 1.8T 0 disk ├─sda2 8:2 0 1.8T 0 part / ├─sda3 8:3 0 977M 0 part [SWAP] └─sda1 8:1 0 512M 0 part /boot/efiTo check if the disk is SSD or HDD (ROTAtional):
$ lsblk -d -o name,rota NAME ROTA sda 0 sdb 0 sdc 1where ROTA == 1 means HDD, and ROTA == 0 means SSD.
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findmntspecialized tool$ findmnt TARGET SOURCE FSTYPE OPTIONS / /dev/sda2 ext4 rw,relatime,errors=remount-ro,data=ordered ├─/sys sysfs sysfs rw,nosuid,nodev,noexec,relatime │ ├─/sys/kernel/security securityfs securityfs rw,nosuid,nodev,noexec,relatime │ ├─/sys/fs/cgroup tmpfs tmpfs ro,nosuid,nodev,noexec,mode=755 │ │ ├─/sys/fs/cgroup/systemd cgroup cgroup rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd │ │ ├─/sys/fs/cgroup/freezer cgroup cgroup rw,nosuid,nodev,noexec,relatime,freezer │ │ ├─/sys/fs/cgroup/rdma cgroup cgroup rw,nosuid,nodev,noexec,relatime,rdma │ │ ├─/sys/fs/cgroup/devices cgroup cgroup rw,nosuid,nodev,noexec,relatime,devices │ │ ├─/sys/fs/cgroup/cpu,cpuacct cgroup cgroup rw,nosuid,nodev,noexec,relatime,cpu,cpuacct │ │ ├─/sys/fs/cgroup/blkio cgroup cgroup rw,nosuid,nodev,noexec,relatime,blkio │ │ ├─/sys/fs/cgroup/net_cls,net_prio cgroup cgroup rw,nosuid,nodev,noexec,relatime,net_cls,net_prio │ │ ├─/sys/fs/cgroup/hugetlb cgroup cgroup rw,nosuid,nodev,noexec,relatime,hugetlb │ │ ├─/sys/fs/cgroup/cpuset cgroup cgroup rw,nosuid,nodev,noexec,relatime,cpuset │ │ ├─/sys/fs/cgroup/perf_event cgroup cgroup rw,nosuid,nodev,noexec,relatime,perf_event │ │ ├─/sys/fs/cgroup/memory cgroup cgroup rw,nosuid,nodev,noexec,relatime,memory │ │ └─/sys/fs/cgroup/pids cgroup cgroup rw,nosuid,nodev,noexec,relatime,pids │ ├─/sys/fs/pstore pstore pstore rw,nosuid,nodev,noexec,relatime │ ├─/sys/firmware/efi/efivars efivarfs efivarfs rw,nosuid,nodev,noexec,relatime │ ├─/sys/kernel/debug debugfs debugfs rw,relatime │ ├─/sys/fs/fuse/connections fusectl fusectl rw,relatime │ └─/sys/kernel/config configfs configfs rw,relatime ├─/proc proc proc rw,nosuid,nodev,noexec,relatime │ └─/proc/sys/fs/binfmt_misc systemd-1 autofs rw,relatime,fd=35,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=55306 ├─/dev udev devtmpfs rw,nosuid,relatime,size=131978096k,nr_inodes=32994524,mode=755 │ ├─/dev/pts devpts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 │ ├─/dev/shm tmpfs tmpfs rw,nosuid,nodev │ ├─/dev/mqueue mqueue mqueue rw,relatime │ └─/dev/hugepages hugetlbfs hugetlbfs rw,relatime,pagesize=2M ├─/run tmpfs tmpfs rw,nosuid,noexec,relatime,size=26402968k,mode=755 │ ├─/run/lock tmpfs tmpfs rw,nosuid,nodev,noexec,relatime,size=5120k │ └─/run/user/1002 tmpfs tmpfs rw,nosuid,nodev,relatime,size=26402968k,mode=700,uid=1002,gid=1002 ├─/data2 /dev/sdb ext4 rw,relatime,data=ordered ├─/data3 /dev/sdc ext4 rw,relatime,data=ordered ├─/data4 /dev/sdd ext4 rw,relatime,data=ordered └─/boot/efi /dev/sda1 vfat rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro $ findmnt / TARGET SOURCE FSTYPE OPTIONS / /dev/sda2 ext4 rw,relatime,errors=remount-ro,data=ordered
Add a new disk
- Plug in the hardware
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Check is it detected
sudo fdisk -l # should see /dev/sdb, /dev/sdc, ...
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(Optional) make partitions
sudo fdisk /dev/sdb # >>> p # >>> n # ...
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make filesystem
sudo mkfs -t ext4 /dev/sdb # sudo mkfs -t ext4 /dev/sdb1 # if partitioned
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mount
sudo mkdir /data2 sudo mount /dev/sdb /data2
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set auto-mount after reboot
sudo vim /etc/fstab # add a line: # <disk> <mount> <filesystem> <option> <dump, should be 0> <pass, root disk shoule be 1, other disk should be 2> /dev/sdb /data2 ext4 defaults 0 2
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check auto-mount
sudo mount -av
testdisk
TestDisk can undelete
- files and directory from FAT12, FAT16 and FAT32 filesystem,
- files from ext2 filesystem,
- files from NTFS partition since version 6.11.
If it doesn't work or for other filesystem! (which means the most used ext4 cannot use it.)
extundelete
Need to unmount the device.
Usually we need a live-USB boot. (very difficult, not recommended)
if the process is not killed (the only practical way)
ref: https://www.jianshu.com/p/662293f12a47
# find the pid that occupies the deleted file.
lsof | grep <deletedfilename>
# copy the proc, then you can find it in /backup
cp /proc/<pid>/fd /backup
$ ls /proc/<pid>/fd
lrwx------ 1 root root 64 1月 18 22:21 0 -> /dev/pts/0
l-wx------ 1 root root 64 1月 18 22:21 1 -> /root/deletefile.txt (deleted)
lrwx------ 1 root root 64 1月 18 22:21 2 -> /dev/pts/0