RAID sync

[Apollon Koutlidis]

V13 wrote:
> On Saturday 12 July 2008, Apollon Koutlidis wrote:
>   
>> Antonis Christofides wrote:
>>     
>>> Αν κάνω reboot πριν τελειώσει το sync, υπάρχει
>>> κανένα πρόβλημα ή θα δουλέψουν όλα καλά και θα συνεχιστεί το sync
>>> ομαλά μετά το boot; Yποθέτω, δεν θα έχω ακόμα αρκετό redundancy που να
>>> επιτρέπει την απομάκρυνση ενός από τους δίσκους, κατά τα άλλα όμως
>>> δουλεύει;
>>>       
>> Egw proswpika antimetwpisa problhma se antistoixh periptwsh: 3 arrays:
>> RAID1, RAID5 me 3 diskous kai RAID5 me 4 diskous, LVM2se Ubuntu hardy
>> x86. Kata th diarkeia tou sync ekana reboot kai mou ta edwse sxedon sto
>> xeri. Ta skoupisa kai 3anarxisa, mou ekane paromoia kolpa. Akoma den exw
>> katalabei ti egine: meta to reboot nomize oti eixa ena RAID5 me 4
>> diskous kai ena me 5, apo to opoio o enas diskos faulty kai o enas apwn
>> gia ka8e array. Telika ekana recreate ta array me --assume-clean kai to
>> afhsa na kanei sync... ektote ola kala. Pi8anon epesa se kapoio periergo
>> bug alla sto mellon 8a perimenw na teleiwsei to sync kalou-kakou :)
>>     
>
> Mipos:
> a) den eixes apenergopoihseis to write caching ton diskon?
>   
Den ekana tipota sxetiko :) htan 3 IDE diskoi (oi 2 sto idio kanali - 
nai malakia alla ti na kanoume, to eftia3a argotera) kai 1 USB.
> *kai*
> b) den ekanes reboot alla shutdown?
>   
Reboot ekana, eimai sigouros gi' auto :)
> Akomi kai me to (a) mono mporei na dimioyrgithei ayto to problima (analoga me 
> to motherboard kai ton controller)
Eimai arketa sigouros oti den htan ekei to problhma. Den hmoun arketa 
safhs sthn perigrafh tou ti sunebh kai ws ena ba8mo o logos einai oti 
den eixa xrono gia polu debugging... Me osa kategrapsa kai osa 8umamai:

Meta to reboot, kanontas examine to array fainotan na exei mple3ei ta 
mpoutia tou. O ka8e diskos eixe diaforetikh apopsh gia thn katastash kai 
ton ari8mo diskwn sto array. An 8umamai kala kata th diarkeia tou sync 
ta RAID5 arrays edeixnan +1 disko (basei twn index numbers sto 
/proc/mdstat) ap' oti 8a eprepe na exoun.

Disclaimer: H empeiria mou me s/w raid se auth thn klimaka einai POLU 
periorismenh kai ws ek toutou mporei na ekana 500 diaforetika pragmata 
la8os.

H protash pou prokuptei apo ta parapanw einai: kalou kakou, an den eisai 
sigouros ti paizetai kai den exeis ore3h gia mperdemata, ase to array na 
teleiwsei to sync prin kaneis reboot. Nai, paganistikh magganeia einai :)

Just my 5 pence

A.