1 CSC 486/586 Network Storage

2 Objectives Familiarization with network data storage technologies Understanding of RAID concepts and RAID levels Discuss capture/acquisition of network data storage media. Create hardware and software RAIDs

3 Network Storage - The Basics Direct Attached Storage (DAS) –storage device that is directly attached to a host system –Most common (at the present) Network Attached Storage (NAS) –data storage mechanism that uses special devices connected directly to the network media –assigned an IP address and can then be accessed by clients

4 Network Storage - The Basics Storage Area Network (SAN) –a network of storage devices that are connected to each other and to a server, or cluster of servers, which act as an access point to the SAN –Fibre channel –iSCSI

5 Network Storage Devices

6 Servers & Hard Drive Arrays

7 RAID Controller (Dell Perc) Most server RAID controllers are SCSI, but some are IDE or SATA. Connects Hard Drives to Motherboard Has both internal and external SCSI connectors, but usually can’t use both at same time. Has built-in BIOS configuration utility for configuring RAID arrays. Keystroke to enter BIOS configuration utility usually displayed during POST.

8 RAID Arrays Redundant Array of Independent Disks (aka Redundant Array of Inexpensive Disks) Fault Tolerance –Mirroring –Parity RAID Levels JBOD - Just a Bunch Of Disks RAID 0 - block-level striping without parity RAID 1 - Mirroring (duplexing) RAID 3 & 7 - byte-level striping with parity RAID 4, 5 & 6 - block-level striping with parity RAID 5 - stripes both data and parity information across three or more drives

9 Multiple RAID Levels Can combine two types of RAIDs to create a more robust and fault tolerant setup (i.e. RAID 10) RAID 0, then RAID 1: Divide the ten disks into two sets of five. Turn each set into a RAID 0 array containing five disks, then mirror the two arrays. (Sometimes called a "mirror of stripes".) RAID 1, then RAID 0: Divide the ten disks into five sets of two. Turn each set into a RAID 1 array, then stripe across the five mirrored sets. (A "stripe of mirrors").

10 Imaging Mirror (RAID 1) Arrays If “Mirrored” only, not mirror and striping combined, complete file system sits on each hard drive…..assuming the 2 disks are synchronized. Can be “handled” in the same manner a single drive desktop computer would be imaged. Use normal imaging tool to take an image of each of the two physical hard drives. Can be software or hardware mirror If a hardware mirror and imaging tool has controller driver for RAID controller, you may image the single “logical” raid array volume instead.

11 Imaging Striped Arrays Data is striped evenly across multiple hard drives. No complete file system sits on each of the hard drive. Can NOT be “handled” in the same manner a single drive desktop computer would be imaged. If you use your imaging tool to image each physical drive, you will have data, but it must be “rebuilt” before it would be meaningful to you. Preferred method is to image the “logical” RAID volume(s) instead of the physical hard drives.

12 Imaging Striped Arrays Imaging tool needs to be able to “see” the logical RAID array volume. May need specific driver for RAID controller on your control boot disk or CD. If you can “see” the logical volume with your imaging tool, you will make an image of it as if it were a single hard drive. Not all new controller drivers are available for Linux boot CDs. Must have “target” drive large enough to hold all the data from imaging the RAID, which may be large depending on the number and size of the disks making up the RAID array.

13 Imaging Striped Arrays If you must image the individual physical disks, you must “rebuild” the data. Sometimes this can be done by duplicating the hardware in the original server, specifically the same RAID controller (and firmware version). If not, there are tools and manual processes to read in the data from the multiple disk images and write out to another target disks after putting the striped blocks back together. You must know the original order of the disks, the block size of the stripes and the parity rotation. Can be very complicated.

14 Imaging consideration It may be a lot of data on the array or NAS. Do you really need it all……TRIAGE!!! May not image the whole thing, just a capture of a specific directory or file(s). Can’t shut it down??? May have to pull it across the network using a client machine. How do I connect to this thing?

15 Questions Use the discussion board, as usual…

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