Disk va fayl tizimlari

Serverdagi nosozliklarning katta qismi bitta sababdan boshlanadi: disk to'lgan. Jurnal yozilmaydi, ma'lumotlar bazasi vaqtinchalik fayl yarata olmaydi, sessiya saqlanmaydi - va hamma narsa tushunarsiz xato bera boshlaydi.

df - qancha joy qolgan #

df -h / | head -1 | tr -s ' '

Filesystem Size Used Avail Use% Mounted on

sudo tune2fs -m 1 /dev/sdb1

Inode - haqiqiy chegara #

df -i / | head -1 | tr -s ' '

Filesystem Inodes IUsed IFree IUse% Mounted on

Har fayl, katalog va havola bitta inode egallaydi. Inode faylning metama'lumotini saqlaydi: egasi, ruxsatlar, o'lchami, vaqt belgilari va ma'lumot bloklariga ko'rsatkichlar.

Fayl nomi esa inode da emas - u katalog yozuvida turadi.

Inode tugashini o'z ko'zingiz bilan ko'ring #

Buni tushuntirish emas, ko'rsatish kerak. 20 MB lik fayl tizimi yaratamiz va unda ataylab juda kam inode qoldiramiz.

umount ulanish 2>/dev/null
rm -rf disk.img ulanish
dd if=/dev/zero of=disk.img bs=1M count=20 status=none
mkfs.ext4 -q -N 32 disk.img
mkdir -p ulanish

mount -o loop disk.img ulanish
df -i ulanish | tail -1 | awk '{print "inode: jami " $2 ", band " $3 ", bo'\''sh " $4}'
df -h ulanish | tail -1 | awk '{print "disk: " $4 " bo'\''sh, " $5 " band"}'
umount ulanish

inode: jami 24, band 12, bo'sh 12
disk: 18M bo'sh, 1% band

Diskning 99% i bo'sh. Endi 12 ta bo'sh inode ni to'ldiramiz:

mount -o loop disk.img ulanish
i=0; while touch ulanish/f$i 2>/dev/null; do i=$((i+1)); done
echo "yaratilgan fayllar: $i"
touch ulanish/oxirgi 2>&1 | head -1
umount ulanish

yaratilgan fayllar: 12
touch: cannot touch 'ulanish/oxirgi': No space left on device

No space left on device - lekin diskda joy bor:

mount -o loop disk.img ulanish
i=0; while touch ulanish/f$i 2>/dev/null; do i=$((i+1)); done
df -h ulanish | tail -1 | awk '{print "bo'\''sh joy: " $4}'
df -i ulanish | tail -1 | awk '{print "inode band: " $5}'
umount ulanish

bo'sh joy: 18M
inode band: 100%

sudo du --inodes -x -d 1 /var | sort -rn | head

for d in /var/*; do echo "$(find "$d" 2>/dev/null | wc -l) $d"; done | sort -rn | head

Joyni kim egallagan #

du -sh /etc 2>/dev/null | awk '{print ($1 ~ /[MG]$/) ? "MB yoki GB tartibida" : "kichik"}'

MB yoki GB tartibida

O'chirilgan, lekin joyni band qilib turgan fayl #

Bu eng chalkashtiradigan holat: fayl o'chirilgan, du uni ko'rmaydi, lekin df joy bo'shamaganini aytadi.

mount -o loop disk.img ulanish
dd if=/dev/zero of=ulanish/katta.bin bs=1M count=10 status=none
exec 9< ulanish/katta.bin
rm ulanish/katta.bin
ls ulanish | grep -c katta.bin || true
df -h ulanish | tail -1 | awk '{print "band: " $3}'
exec 9<&-
sleep 0.3
df -h ulanish | tail -1 | awk '{print "deskriptor yopilgach: " $3}'
umount ulanish

0
band: 11M
deskriptor yopilgach: 46K

Fayl katalogda yo'q (grep -c nol berdi), lekin 11 MB band bo'lib qoldi - va joy faqat fayl deskriptori yopilgach bo'shadi (11M dan 46K ga tushdi).

sudo lsof +L1

Ulash va fstab #

findmnt -no FSTYPE / 

ext4

Doimiy ulash /etc/fstab da yoziladi:

UUID=8f3c1e2a-... /var/www ext4 defaults,noatime 0 2

UUID=8f3c1e2a-... /var/www ext4 defaults,nofail 0 2

/dev/sdc1 /var/www/yuklamalar ext4 defaults,noexec,nosuid,nodev 0 2

Fayl tizimi turlari #

stat -f -c "%T" / 

ext2/ext3

stat -f fayl tizimining oilasini ko'rsatadi - ext4 uchun u ext2/ext3 deydi. Aniq nomni df -T yoki findmnt beradi (yuqorida ext4 chiqqani shundan).

Disk to'lganda - tartib #

#!/bin/bash
CHEGARA=85
df -h -x tmpfs -x devtmpfs --output=pcent,target | tail -n +2 |
while read -r foiz nuqta; do
    son=${foiz%\%}
    if [ "$son" -ge "$CHEGARA" ]; then
        logger -t disk-nazorat -p user.warning \
            "$nuqta $son% to'ldi"
    fi
done

Xulosa #

• Size ≠ Used + Avail: ext4 root uchun 5% zaxira qoldiradi.
• Inode soni fayl tizimi yaratilganda belgilanadi va o'zgarmaydi.
• Inode tugasa, xato bir xil: No space left on device.
• df -h dan keyin doim df -i.
• du da -x bayrog'ini unutmang.
• Disk to'lganda: du -h -x -d 1 / | sort -rh.
• O'chirilgan fayl ochiq deskriptor bilan joyni band qilib turadi.
• Jurnalni rm qilmang - : > fayl bilan bo'shating.
• fstab da UUID= va nofail; o'zgartirgach mount -a bilan sinang.
• Yuklamalar bo'limini noexec,nosuid,nodev bilan ulang.

Keyingi bo'limda tarmoqni ko'ramiz: IP, portlar, DNS va "sayt ochilmayapti" muammosini bosqichma-bosqich topish.