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Guide to Operating Systems, 5 th Edition

Guide to Operating Systems, 5 th Edition. Chapter 7 Using and Configuring Storage Devices. Objectives. After completing this chapter, you will be able to: Describe computer storage Configure local disks Work with different types of volumes and virtual disks Describe cloud storage

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Guide to Operating Systems, 5 th Edition

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  1. Guide to Operating Systems, 5th Edition Chapter 7 Using and Configuring Storage Devices

  2. Objectives After completing this chapter, you will be able to: • Describe computer storage • Configure local disks • Work with different types of volumes and virtual disks • Describe cloud storage • Describe tape drive technologies • Work with storage management tools Guide to Operating Systems, 5th Edition

  3. An Overview of Computer Storage • Files and documents are stored on digital media • People want instant access to whatever they store • Cloud storage services are more popular than ever Guide to Operating Systems, 5th Edition

  4. What is Storage? • Storage – any digital medium that data can be written to and later retrieved • Long-term storage includes: • USB memory sticks (flash drives) • Secure Digital (SD) and Compact Flash (CF) cards • CDs and DVDs • Magnetic tape • Solid-state drives • Hard disk drives Guide to Operating Systems, 5th Edition

  5. What is Storage? • Solid-state drives (SSDs) are very popular for applications requiring greater speed, smaller size, and lower power requirements • Uses flash memory and high-speed interfaces • Has no moving parts and requires less power • Do not yet have the capacity of HDDs • Discussions of computer storage are mainly about traditional HDD storage • Most of the discussion of HDD storage applies to SSDs as well Guide to Operating Systems, 5th Edition

  6. Reasons for Storage • Most uses of computer storage: • Operating system files • User applications • User documents • Virtual memory • Log files • Virtual machines • Database storage Guide to Operating Systems, 5th Edition

  7. Storage Access Methods • Four categories of storage access methods: • Local storage • Direct-attached storage (DAS) • Network-attached storage (NAS) • Storage area network (SAN) Guide to Operating Systems, 5th Edition

  8. Storage Access Methods • Local storage - storage media with a direct, exclusive connection to the computer’s system board through a disk controller • Almost always inside the computer’s case • Usually refers to HDDs or SDDs instead of CD/DVDs • Provides rapid and exclusive access • Disadvantage: only the system where it’s installed has direct access to the storage medium Guide to Operating Systems, 5th Edition

  9. Storage Access Methods • Direct-attached storage (DAS) - similar to local storage but can also refer to one or more HDDs in an enclosure with its own power supply • A DAS device with its own enclosure and power supply can usually be configured as a disk array • Such as a RAID configuration • Some DAS have multiple interfaces so that more than one computer can access the storage medium simultaneously Guide to Operating Systems, 5th Edition

  10. Storage Access Methods • Network-attached storage (NAS) - has an enclosure, power supply, slots for multiple HDDs, a network interface, and a built-in OS tailored for managing shared storage • Sometimes referred to as a storage appliance • NAS is typically dedicated to file sharing • NAS shares files through standard network protocols such as: • Server Message Block(SMB), Network File System (NFS), and File Transfer Protocol (FTP) Guide to Operating Systems, 5th Edition

  11. Storage Access Methods • Storage area network (SAN) - uses high-speed networking technologies to give servers fast access to large amounts of shared disk storage • Most common network technologies used in SANs are Fibre Channel and iSCSI • SANS use the concept of logical unit number (LUN) to identify a unit of storage • LUN is a logical reference point to a unit of storage that could refer to an entire array of disks, a single disk, or just part of a disk Guide to Operating Systems, 5th Edition

  12. Storage Access Methods Figure 7-1 A storage area network Guide to Operating Systems, 5th Edition

  13. Configuring Local Disks • Configuration of local disks can be divided into two categories: • Physical disk properties - involve disk capacity, physical speed, and the interface for attaching a disk to the system • Logical disk properties - include its format and the partitions or volumes created on it Guide to Operating Systems, 5th Edition

  14. Configuring Local Disks • Disk-storage terminology: • Disk drive - a physical component with a disk interface connector and a power connector • Volume - a logical unit of storage that can be formatted with a file system • A disk drive can contain one or more volumes • Partition - an older term that means the same thing as a “volume” but is used with basic disk • Formatting - prepares a disk with a file system used to organize and store files Guide to Operating Systems, 5th Edition

  15. Disk Capacity and Speed Table 7-1 Storage unit equivalents The disk capacity you need depends on how the disk will be used Distinct types of data should be kept on separate disks Guide to Operating Systems, 5th Edition

  16. Disk Capacity and Speed • Disk capacity considerations: • On servers or high-performance workstations, the OS installation should be on a separate disk from data and applications • Virtual memory should be on its own disk, if possible • An SSD is also a good choice for the page file • Using RAID as a fault tolerance option, will combine multiple disks to make a single volume • Overall storage capacity is diminished Guide to Operating Systems, 5th Edition

  17. Disk Capacity and Speed • Factors that affect the speed of HDDs: • Disk interface technology • Rotation speed - servers should have an HDD with a minimum speed of 7200 rpm (10,000-15,000 preferred) • Amount of cache memory installed - 32-64 MB cache sizes are common for server-class drives Guide to Operating Systems, 5th Edition

  18. Disk Interface Technologies • Disk interface - connects a disk to a computer system • Usually with some type of cable • The faster the bus, the faster the system can read from and write to the disk • Most common types of disk interfaces: • SATA • SAS • SCSI Guide to Operating Systems, 5th Edition

  19. Disk Interface Technologies • Serial ATA Drives (SATA) - have mostly replaced parallel ATA (PATA) drives • Advantages: faster transfer times and small cable size • SATA drives are inexpensive, fast, and reliable • Current standard: 3.2 • Supports speeds up to 16 Gb/s Guide to Operating Systems, 5th Edition

  20. Disk Interface Technologies • Small computer system interface (SCSI) drives - a parallel bus technology still used on some servers but has reached its performance limits • Latest variation is Ultra-640 which supports up to 640 MB/s transfer rates • Serial attached SCSI (SAS) - a newer, serial form of SCSI with transfer rates up to 6 Gb/s and higher • SATA drives can be connected to SAS backplanes • Backplane - a connection system that uses a printed circuit board instead of traditional cables to carry signals Guide to Operating Systems, 5th Edition

  21. Disk Interface Technologies • Partitioning methods offered by most OSs: • Master Boot Record (MBR) - most common method that has been around since DOS • Supports volume sizes up to 2 TB • GUID Partitioning Table (GPT) - support volumes sizes up to 18 exabytes (EB, a million terabytes) • Offer improved reliability through partition table replication and Cyclic Redundancy Check (CRC) protection of the partition table Guide to Operating Systems, 5th Edition

  22. Types of Volumes • RAID Arrays – Redundant array of inexpensive (or independent) disks • A disk configuration that uses space on multiple disks to from a single logical volume • RAID is commonly configured in one of two ways: • By the storage controller in hardware • Via the OS storage system in software • Hardware RAID provides better performance by offloading the OS from having to perform the processes involved in RAID Guide to Operating Systems, 5th Edition

  23. Types of Volumes • Common volume types supported by most OSs: • Simple volume - resides on a single disk, basic or dynamic • Spanned volume - extends across two or more physical disks • RAID 0 volume - extends across two or more dynamic disks, but data is written to all disks in the volume equally Guide to Operating Systems, 5th Edition

  24. Types of Volumes • Common volume types supported by most OSs (cont’d): • RAID 1 volume (Mirrored volume ) - uses space from two dynamic disks and provides fault tolerance • Data written to one disk is duplicated, or mirrored, to the second disk • If one disk fails, the other has a copy of the data • RAID 5 volume - uses space from three or more dynamic disks and uses disk striping with parity • Parity information is used to re-create lost data after a disk failure Guide to Operating Systems, 5th Edition

  25. Types of Volumes Figure 7-2 A RAID 0 volume Guide to Operating Systems, 5th Edition

  26. Types of Volumes Figure 7-3 A RAID 1 volume Guide to Operating Systems, 5th Edition

  27. Types of Volumes Figure 7-4 A RAID 5 volume Guide to Operating Systems, 5th Edition

  28. Windows Volumes and Disk Types • Two Microsoft-specific volume definitions: • Boot volume - the volume where the \Windows folder is located (also called boot partition) • System volume - contains files the computer needs to find and load the Windows OS (also called system partition) • In Windows 2008 and later versions, it’s created automatically during installation if you’re installing an OS for the first time on a system • Not assigned a drive letter (can’t be viewed in File Explorer) Guide to Operating Systems, 5th Edition

  29. Windows Volumes and Disk Types Figure 7-5 Boot and system volumes in Disk Management Guide to Operating Systems, 5th Edition

  30. Windows Volumes and Disk Types • Basic Disks - accommodates only basic volumes • Can accommodate only simple volumes • Volumes on a basic disk are called “partitions” • Can support a maximum of four partitions • First three are primary partitions and the fourth is called an extended partition • Primary partition - can be assigned a drive letter, be marked active, and contain the Windows system volume • Extended partition - must be divided into logical drives Guide to Operating Systems, 5th Edition

  31. Windows Volumes and Disk Types • Dynamic Disks - a disk arrangement that can hold up to 128 volumes • Volumes can span multiple disks and be configured for RAID • Can hold the Windows boot or system partition, but only if converted to dynamic after Windows is already installed on the volume • To convert a basic disk to dynamic: • In Disk Management, right-click the disk and Convert to Dynamic Disk Guide to Operating Systems, 5th Edition

  32. Windows Volumes and Disk Types • Virtual hard disk (VHD) file - the format virtual machines running in Hyper-V use for their virtual disks • VHD files can also be created and mounted with Disk Management and used like physical disks • A VHD can also be mounted by double-clicking it in File Explorer (or right-click it and click Mount) • Virtual disks are portable • VHD files can be copied to any location for the purposes of backing up data or allowing it to be used by another computer Guide to Operating Systems, 5th Edition

  33. Windows Volumes and Disk Types • Storage Spaces - a new features in Windows Server 2012 that provides flexible provisioning of virtual storage • Creates volumes from storage pools • Storage pools - a collection of physical disks from which virtual disks and volumes are created and assigned dynamically • Storage Spaces can allocate storage by using thin provisioning • Which uses dynamically expanding disks so that you can provision a large volume Guide to Operating Systems, 5th Edition

  34. Windows Volumes and Disk Types • Storage Spaces uses the concept of just a bunch of disks (JBOD) • Two or more disks appear as a single disk to the OS • With JBOD, you can add a physical disk to a storage pool • Storage Spaces features: • Disk pooling • A collection of physical disks viewed as a single storage space from which volumes can be provisioned for the server’s use. Guide to Operating Systems, 5th Edition

  35. Windows Volumes and Disk Types • Storage Spaces features: • Data deduplication • Data duplicated on a volume multiple times can be reduced to a single instance, thereby reducing space used on the volume. • Flexible storage layouts • Storage Spaces has three storage options, called layouts: • simple space, which can be a simple volume or RAID 0 volume; • mirror space, which is the same as a RAID 1 volume; • parity space, which is the same as a RAID 5 volume. Guide to Operating Systems, 5th Edition

  36. Windows Volumes and Disk Types • Storage Spaces features: • Data deduplication • Data duplicated on a volume multiple times can be reduced to a single instance, thereby reducing space used on the volume. • Flexible storage layouts • Storage Spaces has three storage options, called layouts: • Storage tiering – combines the speed of SSDs with the low cost and high capacity of HDDs. Guide to Operating Systems, 5th Edition

  37. Windows Volumes and Disks Types Figure 7-6 Storage Spaces in Windows 10 Guide to Operating Systems, 5th Edition

  38. Volume Types in Linux/UNIX and Mac OS X • Linux/UNIX and Mac OS X share most terminology for managing storage • Linux volumes can be created using two methods: • Basic partitions – offers same restrictions as basic disks in Windows • Logical volume manager (LVM) – can create as many partitions as you have space and use RAID • LVM uses physical disk partitions called volume groups • From volume groups, logical volumes are created and assigned space Guide to Operating Systems, 5th Edition

  39. Volume Types in Linux/UNIX and Mac OS X • Virtual Disks in Linux – You can work with virtual disks in Linux by: • Creating an image file • Installing a file system on it • Mounting it into the file system • You can also use the Disks utility in GNOME to create a disk image from a hard disk or CD/DVD and attach a disk image • In Mac OS X, use the Disk Utility to create an image from an existing device or folder Guide to Operating Systems, 5th Edition

  40. Volume Types in Linux/UNIX and Mac OS X Figure 7-7 Creating a new disk in Mac OS X Guide to Operating Systems, 5th Edition

  41. Cloud Storage • Cloud storage • Some or all of an organization’s data is stored on servers located offsite and maintained by a storage hosting company • Customers can manage storage by assigning permissions for user access • Advantage of cloud storage • Details of managing and backing up storage on local servers are offloaded to a third party • Examples: Dropbox, Microsoft OneDrive and Google Drive Guide to Operating Systems, 5th Edition

  42. Tapes and Tape Drives • Tape backup systems are a traditional choice for backing up large amounts of data • Use magnetic storage and record data in sequential order • Disadvantage – to find a file near the end of the tape, the drive must first go through all of the data recorded prior to that file • Most popular for long-term storage • With disk drives growing into terabytes, tape drive technology is continuing to evolve in order to keep up Guide to Operating Systems, 5th Edition

  43. Tapes and Tape Drives Table 7-2 Tape media capacities Guide to Operating Systems, 5th Edition

  44. DAT Drives • DAT Drives - Digital audio tape • Use a 4-mm tape and the digital data storage (DDS) format • DDS-1 has a capacity of 2 GB (4 GB compressed) • Current standard is DDS-5 – storage capacity of 36 GB (72 GB compressed) • Backward compatible – can upgrade to a DDS-5 drive and still read DDS-4 tapes • Rated at an archival life of 10 years • Still used for audio recordings, but use for data storage is mostly replaced by other technologies Guide to Operating Systems, 5th Edition

  45. DLT and SDLT Drives • DLT Drives – Digital linear tape • Use half-inch wide magnetic tapes • Record data in tracks • Offers a high-speed search capability • Used in many automated tape backup systems • SDLT Drives – Super digital linear tape • Use both magnetic and optical recording methods • Laser technology can more accurately write data to the tape and allows for greater density of information • DLT/SDLT have an archival life of up to 30 years Guide to Operating Systems, 5th Edition

  46. AIT and S-AIT Drives • AIT Drives – Advanced intelligent tape (AIT) • Used mainly in midrange servers • Tapes have an erasable memory chip inside the cartridge that stores information normally written at the beginning of the tape • Can fast forward and pinpoint information faster • S-AIT Drives – Super advanced intelligent tape • Has a capacity of 500 GB/1.3 TB (native/compressed) • Both of these drives can sustain up to 30,000 tape passes and have an archival life of 30 years Guide to Operating Systems, 5th Edition

  47. LTO Drives • LTO Drives – Linear tape open • Most widely accepted in high-end servers (because of high-speed performance) • Standards are open to the public and are nonproprietary • LTO Ultrium format was developed so that LTO tapes can be used in existing DLT tape drives • Fast data transfer speed up to 240 MBps (noncompressed data) and 120 MBps (compressed data) • Can sustain up to 260 tape passes and have an archival life of 15-30 years Guide to Operating Systems, 5th Edition

  48. Storage Management Tools • This section covers: • Windows Storage Management Tools • Disk Management Tools in UNIX/Linux • Mac OS X Disk Utility Guide to Operating Systems, 5th Edition

  49. Windows Storage Management Tools • Windows Disk Management tool for hard drive and removable enables you to: • Create, format, and delete partitions • Manage partitions • Manage removable storage such as hard drives, DVD/CD-ROM drives, and flash drives • Convert a basic disk to a dynamic disk • Can access this tool from Computer Management console • And by right-clicking Start Guide to Operating Systems, 5th Edition

  50. Windows Storage Management Tools • On Windows 2012/R2 and newer versions • You can use the File and Storage Services tool from Server Manager to manage volumes and Storage Spaces Guide to Operating Systems, 5th Edition

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