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8. FAQs

Edw briskomaste sthn enothta twn syxnwn erwthsewn (FAQs). H enothta ayth basizetai kata ena meros se ena palio keimeno toy Alan Cox, me FAQs gia to NFS.

An exete kapoio problhma sto na kanete mount ena filesystem, parakalw koitajte mhpws to problhma sas periexetai sthn prohgoumenh enothta, th "lista pi8anwn problhmatwn sto mounting toy NFS".

  1. Pairnw polla mhnumata la8oys, toy tupoy : "stale nfs handle" ( = palio programma xeirismou toy nfs), otan xrhsimopoiw to Linux se nfs server.

    Ayta ta projenei kapoio bug merikwn paliwn ekdosewn toy nfsd. To problhma dior8w8hke apo ton nfs-server2.2beta16 kai meta.

  2. Otan prospa8w na kanw mount ena filesystem, pairnw :
      can't register with portmap: system error on send
      
    

    (Dhl. "Den symfwnei h katagrafh ston portmapper, sfalma kata thn apostolh")

    Pi8anotata xrhsimopoieite th dianomh Caldera. Yparxei ena bug sta rc scripts. Parakalw, epikoinwnhste me thn Caldera, gia na sas dwsei ta dior8wmena arxeia.

  3. Giati den mporw na ektelesw ena arxeio, afou to antegraca ston NFS server;

    H aitia einai oti o nfsd bazei sth mnhmh cache ta "anoixta" xrhsimopoioumena arxeia (open file handles), gia na epituxei kaluterh apodosh (kai 8ymh8eite, trexei ston xwro toy xrhsth). Oso o nfsd krataei ena arxeio anoixto (opws px sthn periptwsh poy molis exei gracei kati s' ayto), o pyrhnas den 8a sas afhsei na to ektelesete. Oi nfsds poy einai newteroi apo ekdoseis (peripoy) anoijhs toy 1995, eley8erwnoyn ta anoixta arxeia meta apo liga deyterolepta. Oi palioteroi kollane s' ayta gia meres.

  4. Ta arxeia moy sto NFS einai ola mono gia anagnwsh (read only)

    O NFS server me Linux paei ej orismou se katastash monon anagnwshs. Parakalw, diabaste tis enothtes "Oi mountd kai nfsd", kai "Kanontas export se filesystems", s' ayto edw to HOWTO, kai deite tis selides man gia ta exports kai ton nfsd. 8a xreiastei n' allajete to arxeio /etc/exports.

  5. Kanw mount apo enan NFS server me Linux, kai enw h entolh ls doyleuei, den mporw na diabasw h na gracw arxeia.

    Se palioteres ekdoseis toy Linux, prepei na fortwsete ton NFS server me : rsize=1024,wsize=1024.

  6. Kanw mount apo enan NFS server me Linux, me mege8os block metaju 3500 kai 4000, kai o H/Y krasarei syxna.

    Epomenws, mhn to kanete. Ayto den symbainei me toys pyrhnes 2.0 kai 2.2 . Kai, an den me apata h mnhmh moy, den yparxei problhma oute me ton pyrhna 1.2 .

  7. Mporei to Linux na kanei NFS epanw se TCP;

    Oxi pros to paron.

  8. Pairnw polla perierga mhnumata la8oys, otan prospa8w na kanw mount apo enan H/Y me Linux.

    Bebaiw8eite oti oi xrhstes sas metexoyn se 8 h ligoteres omades. Oi palioteroi servers to zhtane ayto opwsdhpote.

  9. Otan epanekkinw ton H/Y moy, merikes fores kremaei, otan prospa8ei na kanei unmount ena kollhmeno NFS (ws server).

    MHN kanete unmount se NFS servers meta thn epanekkinhsh h ton termatismo leitoyrgias toy H/Y, apla agnohste toys. Den 8a peirajei tipote, an den toys kanete unmount. H sxetikh entolh einai : umount -avt nonfs.

  10. Oi NFS clients me Linux argoun polu, otan epikoinwnoun me H/Y Sun kai BSD.

    Oi eggrafes sto NFS synh8ws einai sugxrones. (Ayto, bebaia, mporeite na to apenergopoihsete, an den sas peirazei na kindynecete na xasete dedomena.) Akomh xeirotera, oi pyrhnes poy basizontai sto BSD mallon adynatoun na doyleuoyn se mikra blocks. Etsi, otan grafete 4 kB dedomenwn (apo enan H/Y me Linux) se paketa toy 1 kB poy xrhsimopoiei to BSD, to teleytaio kanei to ejhs :

            diabase th selida twn 4 kB 
            allaje to 1 kB 
            janagrace ta 4 kB ston disko 
            diabase th selida twn 4 kB 
            allaje to 1 kB 
            janagrace ta 4 kB ston disko 
            k. o. k.
      
    

  11. Otan syndew pollous clients se NFS server me Linux, h apodosh peftei jafnika.

    To prwtokollo NFS xrhsimopoiei tmhmatika (fragmented) paketa UDP. O pyrhnas exei ena orio sto posa tmhmata anoloklhrwtwn paketwn mporei na shkwsei, prin arxisei na ta agnoei. Ston pyrhna 2.2, ayto ry8mizetai se xrono runtime mesw toy /proc filesystem : /proc/sys/net/ipv4/ipfrag_high_thresh kai ipfrag_low_thresh. Ston 2.0 , aytes oi parametroi einai sta8eres kata thn compilation toy pyrhna, kai orizontai sta : .../linux/net/ipv4/ip_fragment.c, IPFRAG_HIGH_THRESH, kai IPFRAG_LOW_THRESH. H shmasia aytwn twn timwn, einai oti apaj kai h apaitoumenh mnhmh twn anoloklhrwtwn kommatiwn UDP ftasei to anw orio ths ("ipfrag_high_thresh") se bytes (256 kB ej orismou stoys pyrhnes 2.2.3 kai 2.0.36), aytomata peftei sto katw ths orio ("ipfrag_low_tresh"). Ayto ginetai me sbhsimo kommatiwn. Ayth h katastash isodynamei sxedon me apwleia kommatiwn, kai th stigmh poy h mnhmh ftanei to anw ths orio, h apodosh toy server sas peftei polu.

    Ta 256 kB einai arketa gia peripoy 30 clients. An exete 60, diplasiaste ta. Kai diplasiaste epishs to katw orio.

  12. Xrhsimopoiw to Linux 2.2 (h metagenestero) me ton knfsd, kai den mporw na kanw mount ston H/Y moy, tupoy AIX, IRIX, Solaris, DEC-Unix...

    O knfsd anakoinwnei oti ylopoiei thn ekdosh 3 toy NFS, alla den to kanei. Yparxei mia epilogh, na ton stamathsete na bgazei ayto to mhnyma. Xrhsimopoieiste thn. 'H, mporeite na 8esete "vers=2" sth lista me tis parametroys toy mount stoys clients.

  13. O tupoy AIX 4 H/Y moy den mporei na kanei mount ton NFS server moy me Linux. Moy leei :
            mount: 1831-011 access denied for server:/dir
            mount: 1831-008 giving up on:
            server:/dir
            The file access permissions do not allow the specified action.
      
    

    (Dhl. : "Den didetai adeia gia ton server", "egkataleipw to server:/dir", "Oi adeies prosbashs sta arxeia den epitrepoyn th drasthriothta poy zhtate.")

    h kati paromoio.

    To AIX 4.2 xrhsimopoiouse rezerbe ports (katw apo to 1024) gia to NFS. Ta AIX 4.2.1 kai 4.3 den periorizontai sta rezerbe ports. Epishs, ta AIX AIX 4.2.1 kai 4.3 prospa8oun na kanoyn mount me xrhsh toy NFS3, meta toy NFS/TCP, kai telika toy NFS/UDP.

    Pros8etontas


    nfso -o nfs_use_reserved_ports=1
    

    sto telos toy rc.tcpip, 8a to anagkasei na janaxrhsimopoihsei ta rezerbe ports. (Ayto to kolpo moy to edwse o Brian Gorka.)


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