Toleransi Kesalahan

"Failure is not an option. It comes bundled with your software "Failure is not an option. It comes bundled with your software.“ (--unknown) "You know you have [a distributed system] when the crash of a computer you've never heard of stops you from getting any work done.“ (--Leslie Lamport)

Some real-world datapoints Drive manufacturers specify the reliability of their products in terms of two related metrics: the annualized failure rate (AFR), which is the percentage of disk drives in a population that fail in a test scaled to a per year estimation; and the mean time to failure (MTTF). Some real-world datapoints Sources: Disk Failures in the Real World: What Does an MTTF of 1,000,000 Hours Mean to You?, Bianca Schroeder and Garth A. Gibson (FAST 07) [pdf] Failure Trends in a Large Disk Drive Population, Eduardo Pinheiro, Wolf-Dietrich Weber, and Luiz André Barroso (FAST’07) [pdf]

Toleransi kesalahan berkaitan dg apa yang disebut kemandirian sistem Toleransi kesalahan berkaitan dg apa yang disebut kemandirian sistem. Beberapa sifat kemandirian: Ketersediaan, kesiapan untuk digunakan Keandalan, keberlanjutan layanan Keamanan, kemungkinan kecil terjadi bencana Dapat diperbaiki, sejauh mana sistem dapat diperbaiki

Sistem dikatakan gagal (fail) apabila tidak mampu memenuhi spesifikasi tekniknya Klasifikasi kesalahan: transient, intermittent, Permanent Fault atau kesalahan suatu sistem : Fail-silent faults atau fail stop faults Bizantine Faults Komponen kesalahan

Penggunaan Redudancy Information redundancy, Time redundancy, Contoh Hamming code ditambahkan pada transmitted data Time redundancy, Contoh, penggunaan atomic transaction physical redundancy. contoh ekstra processor dapat ditambahkan ke System sehingga jika beberapa processor rusak maka System secara keseluruhan masih dapat berfungsi dengan benar activereplication dan primary backup. Penggunaan Redudancy

Keamanan Sistem Tersebar Kemanan Terhadap Infrastruktur Security untuk Host dan Aplikasinya Network Security availability, Integrity Confidentiality Access Control (Authentication dan Authorization) Administration control berdasarkan kebijakan organisasi. Physical control Logical control Accounting Keamanan pada jaringan TCP/IP cryptografi Keamanan Sistem Tersebar

Keamanan Sistem Tersebar Application Layer Security Pretty Good Privacy (PGP) Secure Hypertext Transfer Protocol (S-HTTP) Transport Layer Security Security Sockets Layer (SSL) dan Transport Layer Security (TLS) Secure Shell (SSH) Filtering Network Layer Security IP Security Protocol (IPSec) IPSec Architecture Security Association (SA) Filtering (Access Control List) Keamanan Sistem Tersebar

Keamanan Sistem Tersebar Data Link Layer Security Keuntungan metoda ini yaitu penyusup tidak bisa menentukan alamat pengirim atau penerima. Firewall Packet Filter. Contoh jenis ini adalah Access Control List (ACL) pada router. Proxy Servers Stateful Inspection Access Control List Standard IP Access List Extended IP Access List Lock-and-Key Access List dll Network Address Translation (NAT) Keamanan Sistem Tersebar

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