Davie5/18/2010
Thursday, May 20th @ 5:30pm Ursa Minor Co-sponsored with CSS Guest Speakers
Dr. Craig Rich – TBA James Schneider – Cal Poly “State of the
Network” Address Sean Taylor – Reverse Engineering for
Beginners Free food!
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Friday, May 21st @ 5:30PM98P 2-007 (You better know where
this is!)Games
Starcraft, TF2, FEAR, Bad Company 2 Linux, GotY Edition Consoles welcome
MusicFree food
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Wednesday, May 19th @ 1:00pmSean McAllisterStructured Exception Handling
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Redundant Array of Inexpensive | IndependentDisks
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Combining multiple physical devices to achieve increased performance and/or reliability
Added benefit of a single, large device
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A backup solution. End of story.▪ Stop arguing.▪ You’re stupid.
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RAID functions by combining three concepts to achieve desired results Striping – Splitting data across multiple
disks to maximize I/O bandwidth Mirroring – Storing a copy of the data
across multiple disks to guard against drive failure
Error-correction – Parity calculations to find and repair bad data. Also used to distribute data across drives
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Array – collection of disks that operate as one
Degraded array – array where a component disk is missing, but the array can still function
Failed array – array where enough disks are missing to prevent all functionality
Hot spare – extra disk that will allow a degraded array to repair itself Won’t help failed arrays though
Reshape – modify array size or level04/18/23
Levels 0-6Nested RAID
Combines two levels Just a Bunch Of Disks (JBOD) &
Spanning Concatenates one disk to the end of the
other No performance or reliability
improvements
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Data is striped across multiple disks Minimum of two
No redundancy Lose one disk, lose all data
High read/write throughput Disks can read or write simultaneously
without costly parity calculation Results in array of size n Difficult to reshape, and therefore
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Data is mirrored across multiple disks Minimum of two
Full redundancy Lose all but 1 disk, data still good
High read, low write throughput Read different simultaneously Write same data multiple times
Results in array of size 1 Can be reshaped to RAID 5
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I don’t bother with these Neither should you
RAID 2: Sounds like CS magic http://en.wikipedia.org/wiki/RAID_2#RAI
D_2RAID 3 & 4: Striped with a single disk
for parity Use RAID 5 or 6 instead
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Data is striped across multiple disks Minimum of three (unless you’re retarded
like me) Parity is calculated and distributed
Lose any 1 disk, parity allows it to be regenerated
Increased overhead All reads and writes require calculations
Results in array of size n-1 Can be reshaped to RAID 6
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Data is striped across multiple disks Minimum of three (unless you’re retarded
like me) Parity is calculated and distributed
Lose any 2 disks, parity allows regeneration
Increased overhead All reads and writes require calculations
Results in array of size n-2 Can be reshaped to RAID 5
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Combines striping and mirroringMay tolerate multiple failures
But specific combination of failures may ruin array
Extremely inefficient space usage
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Dedicated CPU & RAM May include battery for cache High throughput for I/O Data on disk may be vendor-specific
and not portable to other controllers (Controller died? Better have an exact replacement!)
OS sees a single device from the BIOS, but may require additional driver
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Relies on host CPU for all calculations
No battery for cacheOS level drivers allow for maximum
portability (within OS families of course) Native to Linux kernel (Woooo!) Windows, BSD, Solaris, OSX all have
support
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Looks and acts like hardware RAID OS sees single BIOS device Requires vendor-specific driver
Performs like software RAID Relies on host CPU & ram No cache battery
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Add filesystems ORUse Logical Volume Management
(LVM) Then add filesystems
Create a storage server Media Backups
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Physical Volumes (PV) Disks, partitions, arrays
Volume Group (VG) Combines PVs into single pool of space
Logical Volumes (LV) Create LVs inside the VG that act like
partitions Don’t need to be continuous Can be added or resized at will
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