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Nachos 2 Equipo: Carlos Eduardo Triana Sarmiento Jonathan Alvarado Mata Obed David Guevara Ibarra
FIFOFIFO is an acronym for First In, First Out, an abstraction relatedto ways of organizing and manipulation of data relative to time andprioritization. This expression describes the principle of a queueprocessing technique or servicing conflicting demands by orderingprocess by first-come, first-served (FCFS) behaviour: what comesin first is handled first, what comes in next waits until the first isfinished, analogous to the behaviour of persons standing in line,where the persons leave the queue in the order they arrive, orwaiting ones turn at a traffic control signal.
LRUThis algorithm differs from that of not recently used in the factthat he only looks at the length of time since it was put to 0 thereference bits of pages, while the algorithm of least recentlyused attempts to provide near-optimal behavior by observing thepages that were used least recently. This type of pages, arestatistically least likely to be used again.Although this algorithm provides good performance in theory, it isexpensive to implement in terms of resources consumed. Thereare several implementations that try to keep the cost and achieveconsiderable performance.
One method is to have a linked list and ordered all the pages inmemory. At the end of the list is the least recently used page, andat first the most recently used. The high cost of this method isbecause every time a page is referenced must be moved in the list,which is time consuming. Another way, which requires hardwaresupport, is to have a counter that is incremented every CPUinstruction. Each time a page is accessed, wins the counter numberat the time. When a page must be removed from memory, you justhave to find which one has the lowest number, which is what wasused for longer. This Counters are not so large to allow this. Dueto the high cost of LRU, we propose similar algorithms, but allowless costly implementations, such as the following.
CacheCache memory is a type of memory, cache memory saves alldata that computer needs to work.But was not the RAM?Well, partly yes. The computers main memory(RAM) andcache memory are basically the same in many respects, thedifference is the use that is given to the cache.The main feature of the cache is very fast, about 5 or 6times the RAM.
The cache can be a reserved area of main memory, like ahigh-speed storage.Two types of cache: ● Cache: a memory of high speed static RAM ● Disk cacheThe cache is effective because the programs access againand again to the same data or instructions.Keeping this information in SRAM, the computer avoidsaccesing main memory.
The cache acts as a summaryof data RAM, and we all knowthat a 500 page summary isnot at all useful.The ideal size depends on the RAM(Mb) Cache(Kb)RAM and the following tableshows it: 1a4 128 o 256 4 a 12 256 12 a 32 512 mas de 32 512 o 1024
Hard Disk DriveHard Disks are coated whit a thin magnetic layer, usually of iron oxide.
Cylinders: concentric circles starting at the outside and end on theinside.Tracks: These are the lines of the disk.Sectors: Each track on the disk is divided in sectors.
Cluster: Is the length of the track taken as a processing unit in eachread or write to the disk, which is equivalent to the length of a sectoron floppy disks or set of 4 or 8 contiguous sectors on disk hard.To write, head is positioned over the cell to record and passedthrough it a current pulse, which creates a magnetic field on thesurface.When reading data from disk is passed over the area that is requiredand will detect a magnetic field as found magnetized in one directionor another, indicate whether the position is stored in a 0 or a 1.In writing case is reversed, the head is a current which causes amagnetic field and depending of the sense of this place a 0 or 1.
Latency on a Hard DiskThere are a number of factors related to speed hard drives tounderstand its operation. ● Time track search ● Speed of rotation ● Access time averageLatency: time it takes for the needle to be placed in the desiredsector Transfer rate: rate at which data (bits) can be transferred fromdisk to the central unit. It depends on the rotational speed anddensity data storage on a track
The latency depends on the speed of rotation and is equalto half the time it takes to describe the disk full turn.Some of the fastest models now have discs that rotate at10000 rpm more to reduce latency. rpm 1 turn every latency 3699 16,66 mseg 8,33 mseg 4500 13,33 mseg 6,66 mseg 5400 11,11 mseg 5,55 mseg 7200 8,33 mseg 4,16 mseg 10000 6,00 mseg 3,00 mseg
Solid State Drive A solid state drive or SSD (Solid State Drive) is a datastorage device that uses a nonvolatile memory such as flashmemory or a volatile memory such as SDRAM, to store data, instead of turntables found in magnetic hard drives. Solid state drives have a lower access time and latency. They are easily interchangeable without having to useadapters or expansion cards to make them compatible with the equipment.
Advantages ● Faster startup, having no need to take courses at a constant speed. ● Great write to speed. ● Faster reading, even 10 times more than traditional hard disks through internal RAIDs on the same SSD. ● Low latency read and write. ● Application launch and boot in less time. Results of the faster read speed and especially the search time. But only if the application resides in flash. ● Lower power consumption and heat production. Result of having no mechanical elements.
● No noise: The same lack of mechanical parts makes them completely inaudible.● Resistant: Can withstand falling, shock and vibration without spoiling and without uncalibrated. ● More secure and unrecoverable deleted data.
Limitations: ● Price: The flash memory prices are considerably higher in price / gigabyte, the main reason for low demand. However, this is not a technical disadvantage. ● Low recovery: After a physical failure data are completely lost because the cell is destroyed. ● Capacity: They have less capacity than a conventional hard drive, which reaches more than three terabytes. ● The number of read and write cycles of these units is reduced as reducing the size of the memory transistors, so the latest have a lower total lifetime.
SATA vs ATAA SATA hard drive is an electromechanical device that is responsible tostore and read large volumes of information at high speeds.The ceramic disks are mounted on a shift that rotates at high speeds.Such disks have a feature called "Hot swappable", which means it canconnect and disconnect without turning off the computer.The ATA standard was originally designed ton connect hard disks, however,developed an extension called ATAPI (ATA Packet Interface) interfacethat allows other storage peripherals (CD-ROM, DVD-ROM drives, etc) inATA interface.
The SATA hard disk can have two measures: ● 3.5 inches (3.5"), for internal hard drives for desktop computers. ● 2.5" internal hard drives for laptops (Notebook).Unit is the byte, but currently used measures like Gigabyte (GB)and Terabytes (TB). For SATA HDD this data can be 80 GB to400 GB.
PerformanceIn addition to being more convenient to install and drawing lesspower, SATA drives have performance benefits that really setthem apart from ATA drives.The most interesting performance feature of SATA is themaximum bandwidth possible. As we have noted, the evolution ofATA drives has seen the data transfer rate reach its maximum at133 MB/second, where the current SATA standard provides datatransfers of up to 150 MB/second. The overall performanceincrease of SATA over ATA can currently be expected to be upto 5% (according to Seagate), but improvements in SATAtechnology will surely improve on that.
PriceComparing ATA drives to SATA drives can be tricky given all of the variables,but in general it is the case that SATA drives will still cost just a bit more thana comparable ATA drive. The gap is closing rapidly though, and as SATAdrives gain in popularity and availability a distinct shift in prices can beexpected. Considering the benefits of SATA over ATA, the potential differenceof a few dollars can easily be justified when considering an upgrade.Computer Geeks currently has a limited selection of SATA drives, but severaltechnical sites, such as The Tech Zone and The Tech Lounge, offer real timeprice guides to see how comparable drives stack up.
RAID DiskRAID, acronym for Redundant Array of Independent Disks(originally Redundant Array of Inexpensive Disks), is a storagetechnology that provides increased reliability and functionsthrough redundancy. This is achieved by combining multiple diskdrive components into a logical unit, where data is distributedacross the drives in one of several ways called "RAID levels"; thisconcept is an example of storage virtualization and was firstdefined by David A. Patterson, Garth A. Gibson, and Randy Katz atthe University of California, Berkeley in 1987 as Redundant Arraysof Inexpensive Disks.RAID is now used as an umbrella term for computer data storageschemes that can divide and replicate data among multiple physicaldrives. The physical drives are said to be in a RAID, which isaccessed by the operating system as one single drive. The
NTFS File SystemNTFS (New Technology File System) is a file system included inWindows NT versions of Windows 2000, Windows XP, WindowsServer 2003, Windows Server 2008, Windows Vista and Windows7. It is based on the HPFS file system from IBM / Microsoft, andalso has some influences from the HFS file format designed byApple.NTFS allows you to define the cluster size, from 512 bytes(minimum size of a sector) independently of the size of thepartition.
FAT 16 File SystemThis is the file system introduced by Microsoft in 1987 to support16bit files. It was designed originally to handle files in a "floppy drive".This file system has a very important set of limitations, amongwhich the maximum of 2GB partition, using cluster 32Kb or 64Kband not support long names files.FAT16 does not support compression and encryption.