> For the complete documentation index, see [llms.txt](https://alicenab.gitbook.io/linux/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alicenab.gitbook.io/linux/redhat/redhat-administration-2-rh134/chapter-6.md). # Chapter 6 **Thin provisioning** is a method of optimizing the utilization of available storage by allocating storage space only as it is needed. **Thick provisioning**, also known as fixed or allocated provisioning, involves allocating the full amount of required storage space at the time of provisioning. To get an overview of currently existing devices: ``` lsblk /dev/sdx - SCSI and SATA disks /dev/vdx - KVM virtual machines /dev/nvmexny - is used for NVME devices ``` Naming convention: ``` /dev/sda2 - second partition on the first hard disk /dev/sdb1 - first partition on te second hard disk /dev/nvme0n1p1 - first partition on the first hard disk /dev/nvme0n3p2 - second partition on the third hard disk ``` ## MBR vs GPT ### MBR: * 512 bytes to store boot information * 64 bytes to store partitions * Place for 4 partitions only with max size of 2 TiB * To use more partitions, extended and logical partitions must be used ### GPT * More space to store partitions * used to overcome MBR limitations * 128 partitions maximum ## Creating partitions Common tools: ``` fdisk - creates MBT and GPT partitions gdisk - creates GPT by default parted- can be scripted easily ``` Aliases: ``` linux - standard linux swap - linux swap uefi - uefi boot lvm - logical volume manager ``` Əgər yeni partition yaradarkən fdisk içində `n` əmrindən sonra bu üç yazı çıxırsa bu o deməkdir ki, MBR partition table olunub həmin disk. Çünki 4 free yer var cəmi, extended partition seçimi var və 128 partitionun yaradılması biraz inanılmazdır. ``` [root@localhost ali]# fdisk /dev/nvme0n1 Command (m for help): n Partition type p primary (0 primary, 0 extended, 4 free) e extended (container for logical partitions) All space for primary partitions is in use ``` MBR-dan istifadə edən zaman əgər 3 primary partition varsa bu zaman dördüncünü mütləq extended partition yaratmaq lazımdır ki, LVM-lərdən istifadə edə bilinsin. ## Filesystems ### Comparison of popular filesystems #### XFS is the default filesystem * fast and scalable * uses CoW(copy on write) to guarantee data integrity * size can be increased, not decreased #### Ext4 was default in RHEL6 and still used * backward compatible to Ext2 * uses journal to guarantee data integrity * size can be increased decreased #### vfat offers multi-OS support * used for shared devices #### btrfs is a new and advanced filesystem ### Creating filesystems ``` [root@localhost ali]# mkfs.[Tab][Tab] mkfs.cramfs mkfs.ext2 mkfs.ext3 mkfs.ext4 mkfs.fat mkfs.minix mkfs.msdos mkfs.vfat mkfs.xfs ``` ### mounting filesystems: ``` # Mount command shows all mounted filesystems, including administrative kernel mounts mount # This command mounts vdb1 filesystem into /mnt folder: mount /dev/vdb1 /mnt # You should unmount filesystem before disconnecting a device umount # lsof command will tell you about open files in mount lsof /mnt # findmnt command shows which filesystem is mounted where in the directory structure findmnt ``` #### Example 1 - using fdisk: 1\) Created partition ``` [root@localhost ali]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sr0 11:0 1 12.8G 0 rom /run/media/ali/Rocky-8-9-x86_64-dvd nvme0n1 259:0 0 50G 0 disk ├─nvme0n1p1 259:1 0 1G 0 part /boot └─nvme0n1p2 259:2 0 49G 0 part ├─rl-root 253:0 0 45.1G 0 lvm / └─rl-swap 253:1 0 3.9G 0 lvm [SWAP] nvme0n2 259:3 0 20G 0 disk [root@localhost ali]# fdisk /dev/nvme0n2 Welcome to fdisk (util-linux 2.32.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): n Partition type p primary (0 primary, 0 extended, 4 free) e extended (container for logical partitions) Select (default p): p Partition number (1-4, default 1): 1 First sector (2048-41943039, default 2048): Last sector, +sectors or +size{K,M,G,T,P} (2048-41943039, default 41943039): +2G Created a new partition 1 of type 'Linux' and of size 2 GiB. Command (m for help): w The partition table has been altered. Calling ioctl() to re-read partition table. Syncing disks. ``` 2\) Created filesystem on this partition: ``` [root@localhost ali]# mkfs.xfs /dev/nvme0n2p1 ``` 3\) Mounted the filesystem: As you can see on the last line, mountpoint of /dev/nvme0n2p1 is /mnt ``` [root@localhost ali]# mount /dev/nvme0n2p1 /mnt [root@localhost ali]# [root@localhost ali]# lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sr0 11:0 1 12.8G 0 rom /run/media/ali/Rocky-8-9-x86_64-dvd nvme0n1 259:0 0 50G 0 disk ├─nvme0n1p1 259:1 0 1G 0 part /boot └─nvme0n1p2 259:2 0 49G 0 part ├─rl-root 253:0 0 45.1G 0 lvm / └─rl-swap 253:1 0 3.9G 0 lvm [SWAP] nvme0n2 259:3 0 20G 0 disk └─nvme0n2p1 259:4 0 2G 0 part /mnt ``` it is also able to seen in `mount` command: ``` [root@localhost ali]# mount | grep '^/' /dev/mapper/rl-root on / type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota) /dev/nvme0n1p1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota) /dev/sr0 on /run/media/ali/Rocky-8-9-x86_64-dvd type iso9660 (ro,nosuid,nodev,relatime,nojoliet,check=s,map=n,blocksize=2048,uid=1000,gid=1000,dmode=500,fmode=400,uhelper=udisks2) /dev/nvme0n2p1 on /mnt type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota) ``` it can also able to seen in `findmnt` command: ``` [root@localhost ali]# findmnt TARGET SOURCE FSTYPE OPTIONS / /dev/mapper/rl-root xfs rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota <-SNIPPED-> └─/mnt /dev/nvme0n2p1 xfs rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,noquota ``` to unmount device: ``` [root@localhost ali]# lsof /mnt lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs Output information may be incomplete. [root@localhost ali]# umount /mnt ``` Əgər `wrong fs type` erroru gəlirsə deməli ya filesystem yaratmaq yadımnan çıxıb ya da extended içindəki logical partitionu mount etmək yerinə extended partitionu mount etməyə çalışıram. #### Example 2 - using gdisk: ``` gdisk /dev/nvme0n2 Partition number (1-128, default 1): 1 First sector (34-41943006, default = 2048) or {+-}size{KMGTP}: Last sector (2048-41943006, default = 41943006) or {+-}size{KMGTP}: +2G Current type is 'Linux filesystem' Hex code or GUID (L to show codes, Enter = 8300): 8e00 Changed type of partition to 'Linux LVM' Command (? for help): p Disk /dev/nvme0n2: 41943040 sectors, 20.0 GiB Model: VMware Virtual NVMe Disk Sector size (logical/physical): 512/512 bytes Disk identifier (GUID): C2535E9B-8E81-47F1-8349-81F3BB14DD79 Partition table holds up to 128 entries Main partition table begins at sector 2 and ends at sector 33 First usable sector is 34, last usable sector is 41943006 Partitions will be aligned on 2048-sector boundaries Total free space is 37748669 sectors (18.0 GiB) Number Start (sector) End (sector) Size Code Name 1 2048 4196351 2.0 GiB 8E00 Linux LVM Command (? for help): w Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING PARTITIONS!! Do you want to proceed? (Y/N): y OK; writing new GUID partition table (GPT) to /dev/nvme0n2. The operation has completed successfully. ``` ## /etc/fstab Mountları reboot persistent etmək üçün mountları fstab-a yazmaq lazımdır ``` /dev/sdb1 /data ext4 defaults 0,0 ``` ``` systemd-fstab-generator systemctl deamon-reload ``` `/etc/fstab`da edilən hər hansı səhvə görə sistem normal boot edilməyə bilər. fstab-ın syntaxını doğrulamaq üçün aşağıdakı komandaları icra etmək lazımdır: ``` mount -a # mount olunmamış filesystemləri mount edir findmnt --verify # fstabda error və warning olmamasına baxır ``` Əgər OS açılmasa, grub boot menuda kernel sətri axırındakı aşağıdakı sətirləri silmək lazımdır ki, errorları görək: ``` rhgb quiet ``` reboot etdikdə 1min30san görsədəcək error olan job complete olmağı üçün. Gözlədikdən sonra shell gələcək. fstab-dakı yazdığımız şeylər systemd mount-a tərcümə edilir OS tərəfindən. fstab-dan yaradılmış fayllara aşağıdakı qovluqda baxmaq mümkündür: ``` ls /run/systemd/generator cat /run/systemd/generator/boot.mount ``` Hər hansı mounta bu komanda ilə də baxmaq mümkündür ``` systemctl cat tmp.mount ``` ### systemctl ilə mountun aktivləşdirilməsi ``` # mount komandasında tmp adı keçən sətirləri ekrana yazdıraq [root@localhost ali]# mount | grep tmp devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=1830940k,nr_inodes=457735,mode=755) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel) tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755) tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,seclabel,mode=755) tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=372084k,mode=700,uid=1000,gid=1000) # systemctl vasitəsilə tmp.mount-u aktivləşdirək [root@localhost ali]# systemctl enable --now tmp.mount Created symlink /etc/systemd/system/local-fs.target.wants/tmp.mount → /usr/lib/systemd/system/tmp.mount. # son sətirdə aktivləşdirdiyimiz mountun əlavə edildiyini görürük: [root@localhost ali]# mount | grep tmp devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=1830940k,nr_inodes=457735,mode=755) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel) tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755) tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,seclabel,mode=755) tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=372084k,mode=700,uid=1000,gid=1000) tmpfs on /tmp type tmpfs (rw,nosuid,nodev,seclabel) # fstab systemctlə çevrildiyi üçün /tmp mountunu fstabda görmək mümkün deyil çünki # heç vaxt burda yazılmamışdı [root@localhost ali]# grep tmp /etc/fstab # tmp.mountun statusuna systemctl əmri vasitəsilə baxırıq: [root@localhost ali]# systemctl status tmp.mount ● tmp.mount - Temporary Directory (/tmp) Loaded: loaded (/usr/lib/systemd/system/tmp.mount; enabled; vendor preset: disabled) Active: active (mounted) since Wed 2024-06-26 10:40:07 +0330; 52s ago Where: /tmp What: tmpfs Docs: man:hier(7) https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems Tasks: 0 (limit: 22886) Memory: 4.0K CGroup: /system.slice/tmp.mount Jun 26 10:40:07 localhost.localdomain systemd[1]: Mounting Temporary Directory (/tmp)... Jun 26 10:40:07 localhost.localdomain systemd[1]: Mounted Temporary Directory (/tmp). ``` ## Persistent naming attributes ``` blkid # shows all devices with their naming attributes tune2fs -L # is used to set a label on an EXT filesystem xfs_admin -L # is used to set a label on an XFS filesystem mkfs.* -L # is used to set a label while creating a filesystem ``` ### XFS UUID clone error Nəyə görə UUİD-ləri istifadə edirik? Əgər 2 partition yaratmışıqsa, məs. /dev/sda5 və /dev/sda6. /etc/fstab içində /dev/sda5-i silsək, əvvəlki /dev/sda6 adını dəyişib /dev/sda5 olacaq çünki ordered numberlə nizamlanır adlar. Bunun qarşısına keçməkçün fstab-da UUİD vermək lazımdır. UUID-lərə bu komanda ilə baxmaq mümkündür: ``` lsblk --fs ``` UUİD vermək qaydası: ``` # bu bizə sda5-in UUID-sini verir blkid | grep sda5 | awk '{ print $2 }' >> /etc/fstab ``` Sonra isə həmin UUID-ni `/etc/fstab` içində yazırıq: ``` UUID="blablabla" /qovluq ext4 defaults 0 0 ``` XFS filesystem clone edildikdə UUID-si də clone olunur. Bu səbəbdən clone edilmiş filesystemə yeni UUID təyin etmək üçün: ``` xfs_admin -U generate /dev/sdb1 ``` ## parted ``` [root@localhost ali]# parted /dev/nvme0n2 unit GiB print Model: NVMe Device (nvme) Disk /dev/nvme0n2: 20.0GiB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 1 0.00GiB 2.00GiB 2.00GiB primary xfs ``` Parted vasitəsilə disk-in partition table-nı GPT-yə çevirmək üçün: {% hint style="danger" %} Əgər diskdə data varsa bu əmrlər həmin dataları siləcək {% endhint %} ``` parted /dev/nvme0n2 mklabel gpt ``` MBR-a çevirmək üçün: ``` parted /dev/nvme0n2 mklabel msdos ``` ### diskə partition table verilməsi və partition yaradılması Bu komanda `/dev/nvme0n2` diskini GPT-yə çevirir, `userdata` adlı partition yaradır, filesystemi `xfs` edir, və ölçünü 1000MB təyin edir: ``` parted /dev/nvme0n2 mklabel gpt mkpart usersdata xfs 2048s 1000MB ``` Bu komanda `/dev/nvme0n2` diskini MBR-a çevirir, primary partition yaradır, filesystemi xfs edir, və ölçünü 1000MB edir: ``` parted /dev/nvme0n2 mklabel msdos mkpart primary xfs 2048s 1000MB ``` Həmin komanda interaktiv formada da icra edilə bilər: ``` [root@localhost ali]# parted /dev/nvme0n2 GNU Parted 3.2 Using /dev/nvme0n2 Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) (parted) mklabel msdos Warning: The existing disk label on /dev/nvme0n2 will be destroyed and all data on this disk will be lost. Do you want to continue? Yes/No? yes (parted) (parted) mkpart Partition type? primary/extended? primary File system type? [ext2]? xfs Start? 2048s End? 3GiB (parted) (parted) print Model: NVMe Device (nvme) Disk /dev/nvme0n2: 21.5GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 1 1049kB 3221MB 3220MB primary xfs lba (parted) quit Information: You may need to update /etc/fstab. [root@localhost ali]# [root@localhost ali]# udevadm settle ``` Bu komanda sistemin yeni partitionu detect edib həmin partitionu `/dev` qovluğunda yaratmasını gözləyir: ``` udevadm settle ``` ## SWAP partition