[linux] odclenenie podadresara na inu particiu

[Jan Ostrochovsky]

Dakujem vsetkym za postupy, nizsie to skusim zosumarizovat, ale najprv
zopar komentarov:

On So, 2008-01-12 at 21:03 +0100, dex wrote:
> zalezi co je to za /var/x adresar ak tam mas nieco pernametne otvorene 
> tak to asi nepojde minimalne bez restartu tej sluzby
> - dovodov je viac umount, fresh copy toho fajlu co je tam open a pod...
> ako si poznamenal je to nezavysle od LVM
> 
> sprav particiu sprav FS (tu mozno je hodne si rozmysliet ci treba 
> journaled FS alebo ani nie podla toho aky typ dat )

na ake veci je vhodnejsi non-journaled?

> mountni to napr /mnt/newvarx
> fuser  /var/x #kukni ci tam nieje nieco open stale alebo niesu nejake 
> kratkodobe pristupy a  ake procesy to pouzivaju

celkom sikovne sa mi vidi skusit viackrat po sebe:
lsof | grep /var/x

> ak nic tak potom len  btw kukni viac krat ono mozes trafit moment kedy 
> tam skutocne nic nepristupuje ale moze neskor

dala by sa zobrazit nejaka historia pristupov? vyssiespomenutym
sondovanim nemusim trafit spravny moment...

> cp -axv <from> <to>
> umount /mnt/newvarx
> tar  cvfz /tmp/povodne-var-x.tar /var/x

asi chyba pripona gz (?)

> #rm -rf /var/x/* # tu sa zamysli ci mas zalohu ten tar ....
> mount /device/xxx /var/x - lebo odtialto by uz povodne fajly pod /var/x 
> neboli dostupne a zaberali flek na povodnej particii
> update /etc/fstab

a teraz ta slubena sumarizacia z viacerych odpovedi na moju otazku,
pripadnym zlepsovacim navrhom sa potesim (snad nevadi switch do inej
language, chcem mat ten postup co najuniverzalnejsi):

Preconditions: root privileges

01. Create partition & filesystem at /dev/new_partition.
02. mkdir /path/to/temp/mountpoint;
mount /dev/new_partition /path/to/temp/mountpoint
03. who; crontab -l (check risk of conflicts with other jobs)
04. Stop correctly all applications (especially db servers) using
migrated files. Alternative ways to achieve that:
    a) step by step stopping apps from list: lsof |
grep /path/to/migrated/directory (without guaranty)
    b) init 1 (unnecessary downtime of some applications)
    c) CALL FOR BETTER SOLUTIONS
05. Backup files to be migrated.
    a) tar
cvfz /path/to/migrated/directory.tar.gz /path/to/migrated/directory
06. Copy files to be migrated. Alternative ways to achieve that:
    a) cp -axvr /path/to/migrated/directory/* /path/to/temp/mountpoint
    b) cd /path/to/temp/mountpoint && tar cpf
- /path/to/migrated/directory | tar xvpf -
    c) rsync -avPH /path/to/migrated/directory/ /path/to/temp/mountpoint
    d) CALL FOR BEST SOLUTION
07. (OPTIONAL) diff --brief
--recursive /path/to/migrated/directory /path/to/temp/mountpoint
08. umount /path/to/temp/mountpoint
09. rm -rf /path/to/migrated/directory/*
10. mount /dev/new_partition /path/to/migrated/directory
11. Follow step 3 backwards, depending on alternative way chosen:
    a) step by step starting apps, which were stopped at step 3a)
    b) init
    c) CALL FOR BETTER SOLUTIONS
12. Add corresponding line to /etc/fstab:
/dev/new_partition    /path/to/migrated/directory    fs_type
options    ...

Jano

> 
> ak som na nieco zabudol niekto ma doplni (gramatiku nerieste :-P)
> Ostrochovský Ján napsal(a):
> >
> > Ahojte,
> >
> > aky mate kto osvedceny sposob na odclenenie podadresara (napr. /var/x) 
> > na osobitnu particiu (resp. osobitnu LV, aj ked tusim, ze ten sposob 
> > bude principialne nezavisly od toho, ci je pouzite LVM alebo nie), nez 
> > je jeho nadradeny adresar (v tomto pripade /var). Optimalne keby to 
> > slo za behu, bez downtime, ale zaroven so zahovanim konzistentnych dat 
> > v prislusnych adresaroch.
> >
> > Vopred dakujem.
> >
> > Jano
> >
> > ------------------------------------------------------------------------
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