1
Q
storage technologies
A
- storage device dimensions/form factors have to be considered
- 3.5 in large form factor (LFF) hard drives are common
- SFF disks = 2.5 in
- storage capacity
- read/write speed
2
Q
HDDs
A
- magnetic disk drives
- vacuum sealed
- contain multiple platters
- spinning disks
- read/write heads on actuator arm for each platter
3
Q
RPMs (HDDs)
A
- faster disk spins
- quicker read/write times
- norm for desktop disks = 7200
- norm for laptop disks = 5400
- faster server HDDs = 15000
4
Q
seek time (HDDs)
A
position of the read/write head over the disk platter determines time to locate data on disk
5
Q
rotational latency
A
- disk platter must spin to correct position to read/write before data is transferred
- usually measured in fractions of a second
6
Q
bus width (HDDs)
A
- amount of bits that can be transferred simultaneously
- fast disk transmission technologies often use serial rather than parallel transmission schemes
7
Q
IOPS (HDDs)
A
- input/output operations per second
- how often a disk can perform I/O operations depends on the specific workload
- generally more IOPS is better
8
Q
transfer rate (HDDs)
A
per second rate at which data is moved into/out of disks indicates the speed of data transfer
9
Q
SSDs
A
- solid state drives
- no moving parts
- more expensive than HDDs
10
Q
SATA
A
- serial advanced technology attachment interface
- used to connect both SSDs and HDDs
11
Q
SSDs in cloud
A
- premium pricing when SSD is used
- opting for disk with higher IOPS value
12
Q
SSHDs
A
- hybrid drives
- combination of hard disk/solid state
- spinning platters and faster flash memory
- cache frequently accessed data on flash memory
13
Q
storage tiers
A
- valuable data should be quickly accessible
- storage tier policies to determine which type of data will be stored on which specific storage media
- hierarchical storage management (HSM)
- place tiered storage capabilities in front of SAN storage
14
Q
SAS (disk interface)
A
- serial-attached SCSI
- serial bit transmission
- hot-pluggable
- newer iteration of older SCSI standard
- more expensive than SATA
- smaller storage capacity than SATA
- designed for constant use
- often used for servers
15
Q
SATA (disk interface)
A
- serial ATA
- serial bit transmission
- not designed for constant use
- used often in personal workstations
16
Q
eSATA (disk interface)
A
- similar to SATA
- interface connector is external to the device
- some devices have built in eSATA port
17
Q
SCSI (disk interface)
A
- small computer system interface
- parallel bit transmission
- used often for servers
18
Q
USB (disk interface)
A
- universal serial bus
- serial bit transmission
- convenient external connectivity
- used often in personal workstations
19
Q
FC (disk interface)
A
- fibre channel
- used in SANs
- host bus adapters are required in server to access SAN storage
- used often for servers
20
Q
serial bit transmission
A
sends data bits one after another over a single channel
21
Q
parallel bit transmission
A
sends multiple data bits simultaneously over multiple channels
22
Q
optical drives
A
- CD/Blu-ray/DVD
- write once ready many (WORM) media
- server may require optical drive to boot from for recovery purposes/install OS
23
Q
cloud storage
A
- can provision/deprovision storage instantly
- only pay for the storage needed
- legal/regulatory restrictions on public cloud storage
- on-premise storage can back up to cloud
24
Q
DAS
A
- direct attached storage
- storage disks are housed inside the server chassis
- storage disks only available locally to that server
25
NAS
- network attached storage
- SMB (Windows)
- NFS (Linux)
- CIFS
- use of higher layer protocols distinguishes NAS from SANs
- servers connect to NAS storage over standard network equipment/using standard protocols
- SANs = highly specialized high-speed networks designed to transmit disk I/O traffic using protocols designed for this use
- NAS can be hardware appliances/servers configured for this purpose
26
CIFS
- common internet file system
| - specific implementation of SMB
27
iSCI
- internet small computer system interface
- makes storage accessible to hosts over standard TCP/IP network on a small scale
- less expensive
- slower
- less reliable
- requires separate network segment/VLAN
28
iSCSI initiators
- can be implemented as hardware/software
- hardware initiators support enhanced options i.e. server booting the OS over network
- initiator needs network address/port to contact target
- specify logical unit number (LUN) using iSCSI qualified name (IQN) after connection is established
29
iSCSI
- hosts disk space on IP network
- disk spaced consumed by servers
- allocated blocks of disk space = LUNs
- iSCSI LUNs can also be consumed by some client OS
30
FCoE
- fibre channel over ethernet
- places disk commands into ethernet frames
- requires converged network adapters (CNAs)
- requires FCoE switches
- requires copper/fiber optic cables
31
FC host bust adapter (HBA)
- enables VMs to communicate with SAN
- installed on hypervisor host
- unique 16-digit hexadecimal identifier called world wide node name (WWNN)
- can have multiple ports
- each port can connect to different FC switches for redundancy
32
SANs
- separate storage from individual hosts
- hosts connect to storage over network
- storage appears to be a local device to host
- use specialized network equipment/network storage protocols i.e. FC
33
fabric
- FC switch with a single WWNN plus a WWPN for each port
| - storage arrays connected to FC switches
34
LUNs
- administrators configure LUNs and LUN masks to determine which servers can use which configured storage
- LUN uniquely identifies disk space on the storage array
- LUN mask is usually configured at the HBA level (prevent Windows server from seeing LUNs used by Linux servers)
35
zoning
- larger SANs use instead of LUN masking
- configured at FC switch level
- doesn't apply to FCoE or iSCSI
- groups nodes into zones
- enables controlling LUN visibility to all nodes in the same zone
- use separate VLANs to achieve this with FCoE or iSCSI
36
necessary features of cloud storage
- pool of resources shared by multiple tenants
- IT services available on demand from anywhere using any device
- rapid elasticity
- user provisioning/deprovisioning
- metered services
37
VSS
- volume shadow service
- volume shadow copy service
- enables data backup without requiring applications to be taken offline during backup
38
disk quotas
- limit how much disk space is used in a folder/by user
- soft quotas don't enforce quota but create log entry
- hard quotas are enforced
39
thin provisioning
- overbooking/overcommitted disk space
- admin adds storage to server
- multiple disk volumes are created and thinly provisioned to include all storage space added to server
- volumes will use disk space as they grow
- don't have to know storage needs in advance
- limited to total disk space physically available
40
compression
- compression tools save space by reducing redundant occurrences of data
- Windows/Linux servers use GUI/command line to work with compression
- Windows compact command
- Linux gzip command
41
data deduplication
- remove redundant data blocks to conserve space
- Windows server includes data deduplication for NTFS volumes
- tools to measure current disk space usage
- Microsoft file server resource manager (FSRM)
42
Windows image files
- .WIM standard file type
| - save storage space by storing multiple images of the same OS within a single file (single-instance storage)
43
DISM
- deployment image servicing and management
- DISM.exe
- tool to work with Windows image files
44
image management tools
- DISM
- imagex.exe
- Microsoft development toolkit (MDT)
- Microsoft system center configuration manager (SCCM)
45
RAID configuration
- redundant array of independent disks
- enables grouping multiple physical disks together as a logical unit
- improved I/O
- fault tolerance
- hardware RAID support usually integrated on server motherboards
- can get expansion cards (RAID controllers)
- software RAID is built into server OS
46
dynamic disks
- required for using software RAID in Windows
- disks start as basic disks
- prompted to convert to dynamic disks when configuring software RAID levels
47
hardware RAID array controllers
- often have battery-backed caches
- cached data is committed to disk after system crashed and is rebooted
- use redundant RAID controllers
48
RAID 0
- uses disk striping
- requires at least 2 disks
- data to be written to disk is broken into blocks (stripes) that are evenly written across the disk array
- improves disk I/O performance
- offers no fault tolerance
49
RAID 1
- uses disk mirroring
- requires at least 2 disks
- data written to disk partition on 1 disk is also written to a disk partition on a different disk
- can use only 50% of disk space
- tolerates disk failure
- doesn't replace backups
50
RAID 5
- uses disk striping with distributed parity
- requires at least 3 disks
- data is striped and evenly written across the disk array
- stores parity (error recovery) information for each stripe on a separate disk from its related data stripe
- tolerates single disk failure
- can reconstruct in memory/on demand any data from failed disk
51
RAID 6
- uses double parity RAID
- requires at least 4 disks
- data is striped and distributed evenly across the disk array
- stores 2 parity (error recovery) strings on each disk
- never stores parity and its related data on same disk
- tolerates 2 disk failures
- can reconstruct in memory/on demand any data from failed disks
52
RAID 10
- uses RAID level 1 then 0
- uses disk mirroring followed by striping
- provides fault tolerance and performance
- requires at least 4 disks
- stripes data across mirrored pairs
- tolerates multiple disk failures and long as they are not in the same mirrored pair
- useful for busy databases
53
making storage space usable
- initialize disks
- partition disks
- formatting partitions with a particular file system
54
disk initialization
- master boot record (MBR)
| - GUID partition table (GPT)
55
disk management tools for Windows
- diskpart.exe
- GUI disk management
- server manager
56
disk management tools for Linux
- fdisk command (MBR)
- gdisk command (GPT)
- logical volume management (LVM)
57
LVM
- logical volume management
| - used to group physical disks together upon which logical volumes can be created
58
file systems supported by Windows server
- file allocation table (FAT)
- FAT32
- extended FAT (exFAT)
- new technology file system (NTFS)
- resilient file system (ReFS)
59
NTFS
- supersedes FAT/FAT32
- journaled file system
- supports compression/encryption/file system security/larger file and partition sizes/user disk quotas
60
FAT32/exFAT
- most commonly used with removable storage
| - can format flash drives as NTFS
61
ReFS
- newer system
- designed to be more resilient to file system corruption
- ability to scan for/correct file system corruption while disk volume is mounted and in use
- doesn't support encrypting file system (EFS)
- doesn't support data deduplication
- can't be used on an OS boot drive
62
file systems supported by UNIX/Linux
- UNIX file system (UFS)
- zettabyte file system (ZFS)
- extended file system (EXT2/EXT3/EXT4)
- reiserFS
63
EXT4/ReiserFS
- common in modern Linux environments
| - journaled file systems
64
journaled file systems
- all file system write transactions are logged before being committed to disk
- makes file system less susceptible to corruption
65
VMFS
- virtual machine file system
- specific to VMware
- designed to support simultaneous read/write activity by cluster nodes concerning VM hard disk files/snapshots
- enables live migration of VMs between VMware ESXi hosts with zero downtime
66
CSVs
- cluster shared volumes
- supported by Microsoft failover clustering
- enables live migration of Hyper-V VMs between clustered Hyper-V hosts with zero downtime
67
hot swappable disks
failed disks can be replaced while everything stays running
68
hot spares
extra disks plugged in but not currently in use
69
cold spares
- extra disks that can be swapped out when used disks fail
| - requires that system is shut down
70
most common disk interface in servers
SAS
71
tier 2 storage
HDD
72
VMFS benefit over NTFS
enable multiple cluster nodes to read/write to the same file system simultaneously
