Foundations — Fault tolerance — fail-safe vs fail-operational

5.5.26 · D1 · Coding › Embedded Systems & Real-Time Software › Fault tolerance — fail-safe vs fail-operational

Is page par assume kiya gaya hai ki tumne kuch bhi nahi dekha. Parent note the parent topic ka har letter, har squiggle, har fraction yahan se ground up mein, usi order mein banaya gaya hai jis order mein tumhe chahiye. Kabhi aage mat kaodo — har symbol ko earn kiya jaata hai use karne se pehle.

"Failure rate" kya hoti hai aur uske liye letter kyun?

Rate kyun, sirf "failing ka chance" kyun nahi? Kyunki failure time ke saath build up hoti hai. Jo part ek ghante mein aasaani se survive kare woh zaruri nahi ki hazaar ghante survive kare. Ek rate humein kisi bhi length of time ke baare mein poochhne deti hai. Neeche di gayi picture dekho.

Lal staircase time ke sath daayein jaate hue failures count karti hai. Iska average steepness exactly $\lambda$ hai — symbol ka poora matlab yehi hai.

Number $e$ aur "time $t$ tak survive karna"

Parent note mein baar baar $e^{-\lambda t}$ aata hai. Aaiye iske har piece ko earn karte hain.

Letter $P$ — probability, 0 aur 1 ke beech ki number

Toh $P(\text{part still works at }t)=R(t)=e^{-\lambda t}$ bas ek hi idea hai, do tarike se likha. Aur chance ki woh time $t$ tak fail ho gaya hai, woh bacha hua sab hai:

Failures ko todna: ${\lambda }_s$, ${\lambda }_d$ aur fraction $\beta$

Har failure equally buri nahi hoti. Ek signal jo accident se dark ho jaata hai (irritating par safe) alag hai uss ek se jo GREEN dikhata hai jab RED hona chahiye (deadly). Parent note $\lambda$ ko do streams mein todta hai.

Ab total rate do chhhoti rates mein split hoti hai, jaise ek nadi do hissa ho jaati hai:

Split kyun karte hain? Kyunki fail-safe design sirf dangerous trickle ${\lambda }_d$ ki parwah karta hai. $\beta$ ko $1$ ke paas le jaane se woh trickle almost kuch nahi ho jaati — yahi fail-safe systems ki poori engineering game hai.

Integral $\int$ aur "average time until..."

Parent note mein likha hai $\text{MTTDf}={\int }_0^{\infty }{e}^{-{\lambda }_{d}t}dt$. Do naye symbols: $\int$ aur MTTDf.

Same machine ko dangerous stream par apply karo aur parent ka headline result milta hai: $\text{MTTDf}={\int }_0^{\infty }{e}^{-{\lambda }_{d}t}dt=\frac{1}{{\lambda }_d}=\frac{1}{(1-\beta )\lambda }$

Redundant units count karna: $\left(\genfrac{}{}{0ex}{}{3}{1}\right)$ aur voting

Fail-operational systems spares use karte hain. Kitne tarike se spares fail ho sakte hain yeh count karne ke liye ek aur notation chahiye.

Isliye parent TMR reliability ko ek sum ki tarah likhta hai: "teeno theek" plus "exactly ek kharab" — woh do situations jahan majority abhi bhi jeetti hai.

Baaki alphabet, jaldi earn karo

Foundations topic ko kaise feed karte hain

Equipment checklist

Reveal karne se pehle jawab zor se bolo. Agar koi atka de, woh section dobara padho.