Jerin RHCSA: Gudanar da Tsari a cikin RHEL 7: Boot, Rufewa, da Duk abin da ke Tsakanin - Sashe na 5

Za mu fara wannan labarin tare da taƙaitaccen bitar abin da ke faruwa tun lokacin da kuka danna maɓallin wuta don kunna sabar RHEL 7 ɗin ku har sai an gabatar muku da allon shiga a cikin layin umarni.

Lura cewa:

1. Ka'idodin asali iri ɗaya suna aiki, tare da ƙila ƙananan gyare-gyare, zuwa sauran rarrabawar Linux kuma, da
2. bayanin da ke biyo baya ba a yi niyya don wakiltar cikakken bayani game da tsarin taya ba, amma kawai mahimman bayanai.

Linux Boot Process

1. POST (Power On Self Test) yana farawa kuma yana yin binciken kayan aiki.

2. Lokacin da POST ya ƙare, tsarin sarrafa tsarin yana wucewa zuwa matakin farko na bootloader, wanda aka adana a kan ko dai ɓangaren taya na ɗaya daga cikin manyan diski (don tsofaffin tsarin ta amfani da BIOS da MBR), ko kuma (U) EFI. bangare.

3. Matakin farko na bootloader sai ya loda bootloader na mataki na biyu, yawanci GRUB (GRand Unified Boot Loader), wanda ke zaune a ciki /boot, wanda kuma yana loda kernel da tsarin fayil na farko na RAM (wanda aka sani da initramfs). , wanda ya ƙunshi shirye-shirye da fayilolin binary waɗanda ke aiwatar da ayyukan da ake buƙata don haɓaka ainihin tushen tsarin fayil).

4. An gabatar da mu tare da fuskar bangon waya wanda ke ba mu damar zaɓar tsarin aiki da kernel don taya:

5. Kwayar tana saita kayan aikin da aka makala a cikin tsarin kuma da zarar an shigar da tushen fayil ɗin, ƙaddamar da tsari tare da PID 1, wanda hakan zai fara wasu hanyoyin kuma gabatar mana da saurin shiga.

Lura: Idan muna son yin haka nan gaba, za mu iya bincika ƙayyadaddun wannan tsari ta amfani da umarnin dmesg tare da tace abubuwan da aka fitar ta amfani da kayan aikin da muka yi bayani a cikin kasidun da suka gabata na wannan silsilar.

A cikin misalin da ke sama, mun yi amfani da sanannun umarnin ps don nuna jerin hanyoyin da ake amfani da su na yanzu waɗanda tsarin iyayensu (ko a wasu kalmomi, tsarin da ya fara su) an tsara su (tsari da mai sarrafa sabis wanda yawancin rarrabawar Linux na zamani suka canza). to) lokacin farawa tsarin:

# ps -o ppid,pid,uname,comm --ppid=1

Ka tuna cewa -o flag (gajeren --format) yana ba ka damar gabatar da fitarwa na ps a cikin tsari na musamman don dacewa da bukatunku ta amfani da kalmomin da aka ƙayyade a cikin STANDARD FORMAT SPECIFIERS sashe a cikin mutum ps.

Wani shari'ar da zaku so ayyana fitowar ps maimakon tafiya tare da tsoho shine lokacin da kuke buƙatar nemo hanyoyin da ke haifar da babban nauyin CPU da/ko ƙwaƙwalwar ajiya, kuma ku tsara su daidai:

# ps aux --sort=+pcpu              # Sort by %CPU (ascending)
# ps aux --sort=-pcpu              # Sort by %CPU (descending)
# ps aux --sort=+pmem              # Sort by %MEM (ascending)
# ps aux --sort=-pmem              # Sort by %MEM (descending)
# ps aux --sort=+pcpu,-pmem        # Combine sort by %CPU (ascending) and %MEM (descending)

Gabatarwa ga SystemD

Yanke shawara kaɗan a duniyar Linux sun haifar da ƙarin cece-kuce fiye da ɗaukar tsarin manyan rarraba Linux. Sunan Systemd's masu ba da shawara a matsayin babban fa'idodinsa masu zuwa:

Karanta Hakanan: Labarin Bayan 'init' da 'systemd'

1. Systemd yana ba da damar ƙarin aiki don yin aiki a layi daya yayin farawa na tsarin (kamar yadda ya saba da tsofaffi SysVinit, wanda ko da yaushe yakan kasance a hankali saboda yana fara tafiyar matakai daya bayan daya, bincika idan daya ya dogara da wani, sannan yana jiran daemons don ƙaddamar da haka. ƙarin ayyuka na iya farawa), kuma

2. Yana aiki azaman sarrafa kayan aiki mai ƙarfi a cikin tsarin gudana. Don haka, ana fara ayyuka lokacin da ake buƙata (don guje wa cinye albarkatun tsarin idan ba a yi amfani da su ba) maimakon a ƙaddamar da su ba tare da ingantaccen dalili ba yayin taya.

3. Daidaituwar baya tare da rubutun SysVinit.

Systemd ana sarrafa shi ta hanyar tsarin amfani na systemctl. Idan kun fito daga asalin SysVinit, da alama za ku saba da:

1. kayan aikin sabis, wanda -a cikin tsoffin tsarin- aka yi amfani da shi don sarrafa rubutun SysVinit, da
2. Chkconfig utility, wanda ya yi aiki da manufar sabuntawa da kuma tambayar bayanan runlevel don ayyukan tsarin.
3. rufewa, wanda dole ne ka yi amfani da shi sau da yawa don sake farawa ko dakatar da tsarin aiki.

Tebu mai zuwa yana nuna kamance tsakanin amfani da waɗannan kayan aikin gado da systemctl:

Systemd kuma ya gabatar da ra'ayoyin raka'a (wanda zai iya zama ko dai sabis, wurin dutse, na'ura, ko soket na cibiyar sadarwa) da kuma hari (wanda shine yadda tsarin ke sarrafa fara aiwatar da abubuwa da yawa a lokaci guda, kuma ana iya la'akari da su - ko da yake ba daidai ba - kamar daidai da matakan runlevel a cikin tsarin tushen SysVinit.

Takaitawa

Sauran ayyuka masu alaƙa da sarrafa tsari sun haɗa da, amma ƙila ba za a iyakance su ba, ikon zuwa:

Ana yin wannan ta hanyar kayan aikin renice, wanda ke canza fifikon tsara lokaci ɗaya ko fiye da tafiyar matakai. A cikin sauƙi, fifikon tsara fasalin fasalin ne wanda ke ba da damar kernel (a halin yanzu a cikin juzu'i => 2.6) don ware albarkatun tsarin kamar yadda aka ba da fifikon aiwatarwa (aka niceness, a cikin kewayo daga -20 zuwa 19) na tsari da aka bayar.

Asalin ma'anar renice shine kamar haka:

# renice [-n] priority [-gpu] identifier

A cikin jumlar umarnin da ke sama, hujja ta farko ita ce ƙimar fifiko da za a yi amfani da ita, yayin da sauran gardamar za a iya fassara su azaman ID ɗin tsari (wanda shine saitin tsoho), ID na rukuni na tsari, ID na mai amfani, ko sunayen mai amfani. Mai amfani na yau da kullun (banda tushen) zai iya canza tsarin fifikon tsarin da ya mallaka kawai, kuma kawai yana haɓaka matakin kyawun (wanda ke nufin ɗaukar ƙasa da albarkatun tsarin).

A cikin ƙayyadaddun sharuddan, kashe tsari yana ba da damar aika sigina zuwa ko dai ya gama aiwatar da shi cikin alheri (SIGTERM=15) ko kuma nan da nan (SIGKILL=9) ta hanyar kashe ko umarni pkill.

Bambanci tsakanin waɗannan kayan aikin guda biyu shine cewa ana amfani da na farko don ƙare takamaiman tsari ko ƙungiyar tsari gaba ɗaya, yayin da na ƙarshe ya ba ku damar yin daidai da suna da sauran halaye.

Bugu da ƙari, pkill yana zuwa tare da pgrep, wanda ke nuna muku PIDs waɗanda za a shafa idan an yi amfani da pkill. Misali, kafin gudu:

# pkill -u gacanepa

Yana iya zama da amfani duba a kallo waɗanda PIDs mallakar gacanepa:

# pgrep -l -u gacanepa

Ta hanyar tsoho, duka kisa da pkill suna aika siginar SIGTERM zuwa tsarin. Kamar yadda muka ambata a sama, ana iya watsi da wannan siginar (yayin da tsarin ya ƙare aiwatar da shi ko kuma mai kyau), don haka lokacin da kuke buƙatar dakatar da aiwatar da aiki tare da ingantaccen dalili, kuna buƙatar saka siginar SIGKILL akan layin umarni:

# kill -9 identifier               # Kill a process or a process group
# kill -s SIGNAL identifier        # Idem
# pkill -s SIGNAL identifier       # Kill a process by name or other attributes 

Kammalawa

A cikin wannan labarin mun bayyana tushen tsarin taya a cikin tsarin RHEL 7, kuma mun bincika wasu kayan aikin da ke samuwa don taimaka maka tare da gudanar da matakai ta amfani da kayan aiki na yau da kullum da ƙayyadaddun umarni na tsarin.

Lura cewa wannan jerin ba a yi niyya don rufe duk karrarawa da whistles na wannan batu ba, don haka jin daɗin ƙara kayan aikin da kuka fi so da umarni zuwa wannan labarin ta amfani da sigar sharhi da ke ƙasa. Tambayoyi da sauran sharhi kuma ana maraba da su.