Davie 5/18/2010

 Thursday, May 20 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! 12/2/2015

 Friday, May 21 5:30PM  98P (You better know where this is!)  Games  Starcraft, TF2, FEAR, Bad Company 2  Linux, GotY Edition  Consoles welcome  Music  Free food 12/2/2015

 Wednesday, May 19 1:00pm  Sean McAllister  Structured Exception Handling 12/2/2015

Redundant Array of Inexpensive | Independent Disks 12/2/2015

 Combining multiple physical devices to achieve increased performance and/or reliability  Added benefit of a single, large device 12/2/2015

 A backup solution.  End of story. ▪ Stop arguing. ▪ You’re stupid. 12/2/2015

 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 12/2/2015

 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 level 12/2/2015

 Levels 0-6  Nested 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 12/2/2015

 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 expand 12/2/2015

 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 12/2/2015

 I don’t bother with these  Neither should you  RAID 2: Sounds like CS magic   RAID 3 & 4: Striped with a single disk for parity  Use RAID 5 or 6 instead 12/2/2015

 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 12/2/2015

 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 12/2/2015

 Combines striping and mirroring  May tolerate multiple failures  But specific combination of failures may ruin array  Extremely inefficient space usage 12/2/2015

 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 12/2/2015

 Relies on host CPU for all calculations  No battery for cache  OS level drivers allow for maximum portability (within OS families of course)  Native to Linux kernel (Woooo!)  Windows, BSD, Solaris, OSX all have support 12/2/2015

 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 12/2/2015

 Add filesystems OR  Use Logical Volume Management (LVM)  Then add filesystems  Create a storage server  Media  Backups 12/2/2015

 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 12/2/2015