Chapter 4e Snia-ssm-tape-slides-2003-04-13
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Obligatory rubric • Copyright © 2002,2003 Storage Networking Industry Association (SNIA). • SNIA-TC members may use this material freely; all others must conform to usage notes in the speaker noted for this slide. • See SNIA-SSM-colors.ppt for printing and color/graphics conventions.
1
Copyright © 2000,2003, Storage Networking Industry Association
Tape and the SNIA sharedstorage model
This revision: • 2002-06-12: last content update • 2003-04-13: last graphics update Copyright © 2002,2003 Storage Networking Industry Association
Scope • Open Systems Mainframe tape function and usage are qualitatively different
• Backup/archive/HSM motivate architectural choices The only significant open system usage of tape
• Backup architecture examples Goal: Explain use of storage networking for backup/restore Non-goal: explain all backup application features/functions
3
Copyright © 2002,2003 Storage Networking Industry Association
Tape layout: logical tape structure (representative) tape extent (sequence of tape blocks)
tape extent separator (e.g., file mark)
(optional) tape header
(optional) tape trailer
tape tape image image
4
Copyright © 2002,2003 Storage Networking Industry Association
Tape layout: physical tape structures (representative) 1. tape contents = single tape image 2. single tape holds multiple tape images, tape image separators 3. tape image(s) spans multiple tapes
5
Copyright © 2002,2003 Storage Networking Industry Association
Tapes are not Disks: Part 1: Physical Format • Physically: Disk block ~= Tape block Disk volume ~= Tape extent • Sequences of blocks
• But … Disk: random access Tape: sequential access • Random access tape (e.g., DECtape) ~= long thin slow disk
• Causes huge usage differences Tape extent is usually written in one pass • Appends occur, but not update in place
Random access to tape is (usually) a bad idea 6
Copyright © 2002,2003 Storage Networking Industry Association
Tapes are not Disks Part 2: Logical Format • Disk block ~= Tape block • Disk volume ~= Tape extent Block aggregation operations apply to both Concatenate, stripe, mirror, etc.
• In OS/360-derived “mainframe” systems: Disk file ~= Tape file
• In open systems: Tape images usually used for packed files “archives”, “backups”, ~= file system
7
Copyright © 2002,2003 Storage Networking Industry Association
The SNIA shared storage model
8
File/record layer Database (dbms)
File system (FS)
Host Network
Block aggregation
Device
Storage Storage devices devices (disks, (disks, …) …)
Block layer
Copyright © 2002,2003 Storage Networking Industry Association
Services
Storage domain
Application
Tape in the SNIA shared storage model Storage domain 9
File/record layer Database (dbms)
File system (FS)
Tape-format system
Tape application (e.g. backup software)
Application
Host
Host Network
Block aggregation
Device
Storage Storage devices devices (disks, (disks, …) …)
Block layer
Copyright © 2002,2003 Storage Networking Industry Association
Sequential Network Extent Access Device aggregation
Tape Tape devices devices Tape Tape media media
Tape in the SNIA shared storage model
10
Tape application (e.g. backup software)
This packsFile/record files/records into layer tape extents/images.
Database File system (dbms) In open systems, (FS) all “host”resident functions take place in the tape application (e.g., backup software). Host Disk accesses Network can be random; Block tape is sequential; unit of Device aggregation aggregation is thus “extents”, not blocks This split is caused by
Storage devices (disks, …) Storage devices (disks, removable media (very…)
important for tape); removable Block layer disks (e.g., CD, DVD) could also be shown on disk side. Copyright © 2002,2003 Storage Networking Industry Association
Tape-format system
Storage domain
Application
Host
Sequential Network Extent Access Device aggregation
Tape Tape devices devices Tape Tape media media
Removable media: Significant functional impacts • Which tape is in the drive? What’s on it? Tape labels, indexes
• Where’s the tape I wanted? Catalogs, library slot management
• How do I get that tape into the drive?
Tape Tape devices devices Tape Tape media media
Operator instructions, robot commands Tape device could be a single drive or multi-drive library
• Can this drive read that tape? Different cartridge sizes and shapes Tape formats: significantly more diverse and complex than SD/DD/HD floppy formats 11
Copyright © 2002,2003 Storage Networking Industry Association
Backup techniques focus on: what is done • Three common Unix tape utilities tar – read the filesystem and write the tape dump – read the disk volume and write the tape dd – bulk copy from disk volume to tape
• Diagrams show data flows for backup Where the disk and tape are doesn’t matter Reverse the data flow arrows for restore
12
Copyright © 2002,2003 Storage Networking Industry Association
Backup technique: Files File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, tar)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 13
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Segment layer
Backup technique: File system volume File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, dump)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 14
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Segment layer
Backup technique: Volume copy to tape File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, dd)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 15
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Backup technique: Files to virtual tape File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, tar)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 16
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Backup architectures focus on: where it is done • Architecture is independent of backup technique • How does the data move to the tape(s)? Architecture examples focus on external tape libraries • External: on different system from backup software
See previous slides for internal tape • Internal: on same system as backup software
17
Copyright © 2002,2003 Storage Networking Industry Association
What’s in a tape library? • Tapes (media)
Tape library
And slots to store them
• Tape drive(s) Often more than one Independently usable
• Robot(s) Move tapes between drives and storage slots Independent command interface
• Robot command paths omitted from diagrams on following slides for clarity
18
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Direct-attach tape •• Direct-attach Direct-attach Tape Tape backup backup
Host with LVM
File/record layer
Backup software
Host block-aggregation
Block layer
Network block-aggregation
Device block-aggregation Disk array Tape library
19
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: LAN-attach tape Backup SW
•• LAN LAN Backup Backup
Host, no LVM
LAN
Host with LVM
File/record layer
Backup SW
Host block-aggregation
Block layer
Network block-aggregation
Device block-aggregation Disk array Tape library
20
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Shared tape drive LAN
Backup SW
LAN-Free LAN-Free Backup Backup Sequential Sequential sharing sharing of of same same tape tape drive drive
Host with LVM
Host with LVM
File/record layer
Backup SW
Host block-aggregation
Block layer
SN
Device block-aggregation Disk array Tape library
21
Network block-aggregation
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Partitioned tape library Backup SW
Host with LVM
Host with LVM
File/record layer
Backup SW
•• Multiple Multiple backups backups at the same at the same time time Robot, Robot, drive, drive, and and tape usage must tape usage must be be coordinated coordinated among among backups backups Host block-aggregation
Block layer
SN
Device block-aggregation Disk array Tape library
22
Network block-aggregation
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Virtual Tape Controller
Host with LVM
File/record layer
Backup Software
SN SN device device virtualizes virtualizes tapes, tapes, tape tape devices devices and/or and/or robots robots
Host block-aggregation
Block layer
Network block-aggregation Virtual Tape Controller Device block-aggregation Disk array Tape library
23
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Virtual Tape Controller + Disk cache Backup Software
Disk Disk used used as as cache cache •• Backup Backup to to Disk Disk
Host with LVM
File/record layer
•• Destage Destage to to Tape Tape
Host block-aggregation
Block layer
Network block-aggregation Virtual Tape Controller Device block-aggregation Disk array Tape library
24
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Data movers for tape
Host with LVM
Host with LVM
File/record layer
Backup software
Server-Free Server-Free Backup Backup Backup Backup software software controls controls library library and and data movement data movement Command/control path
Block layer
Host block-aggregation
25
SN
Movement appliance
Network block-aggregation
Device block-aggregation Disk array
Movement appliance Tape library
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: File-server with tape drive File/record layer
Backup software Host
Host LAN
NAS system
NDMP NDMP Local Local Backup Backup Backup Backup software software uses uses NDMP NDMP to to control control data data movement movement and and tape tape Could Could use use NAS NAS head head instead of NAS system instead of NAS system
Host block-aggregation
Block layer
Network block-aggregation
26
Copyright © 2002,2003 Storage Networking Industry Association
Device block-aggregation
Backup architecture: File-server with external tape NDMP NDMP 3-Way 3-Way Backup Backup
File/record layer
Backup software Host
SN SN may may be be LAN LAN or or SAN SAN Backup Backup software software uses uses NDMP NDMP to to control control data data movement movement and and tape tape
bHost LAN
Could Could use use NAS NAS system system instead of NAS head instead of NAS head
NAS head
Block layer
Host block-aggregation Network block-aggregation
SN
Device block-aggregation Disk array Tape library
27
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: File-server with data mover File/record layer
Backup software Host
NDMP NDMP 3-Way 3-Way Backup Backup Backup Backup software software uses uses NDMP NDMP to to control control data data movement movement and and tape tape
bHost LAN
Block Block commands commands issued issued to to movement appliance movement appliance
NAS head Host block-aggregation
Block layer
Network block-aggregation SN Movement appliance
Device block-aggregation
Disk array Tape library
28
Copyright © 2002,2003 Storage Networking Industry Association
Conclusions • Tape functionality addition to SNIA SSM Parallel functionality to existing disk-based model Backup is the motivating usage
• Open systems backup techniques What can be done E.g., Files (tar), filesystem (dump), device (dd)
• Open systems backup architectures Where it can be done Examples include LAN-free and Server-free backups Also NDMP backups of fileservers
29
Copyright © 2002,2003 Storage Networking Industry Association
1
Copyright © 2000,2003, Storage Networking Industry Association
Tape and the SNIA sharedstorage model
This revision: • 2002-06-12: last content update • 2003-04-13: last graphics update Copyright © 2002,2003 Storage Networking Industry Association
Scope • Open Systems Mainframe tape function and usage are qualitatively different
• Backup/archive/HSM motivate architectural choices The only significant open system usage of tape
• Backup architecture examples Goal: Explain use of storage networking for backup/restore Non-goal: explain all backup application features/functions
3
Copyright © 2002,2003 Storage Networking Industry Association
Tape layout: logical tape structure (representative) tape extent (sequence of tape blocks)
tape extent separator (e.g., file mark)
(optional) tape header
(optional) tape trailer
tape tape image image
4
Copyright © 2002,2003 Storage Networking Industry Association
Tape layout: physical tape structures (representative) 1. tape contents = single tape image 2. single tape holds multiple tape images, tape image separators 3. tape image(s) spans multiple tapes
5
Copyright © 2002,2003 Storage Networking Industry Association
Tapes are not Disks: Part 1: Physical Format • Physically: Disk block ~= Tape block Disk volume ~= Tape extent • Sequences of blocks
• But … Disk: random access Tape: sequential access • Random access tape (e.g., DECtape) ~= long thin slow disk
• Causes huge usage differences Tape extent is usually written in one pass • Appends occur, but not update in place
Random access to tape is (usually) a bad idea 6
Copyright © 2002,2003 Storage Networking Industry Association
Tapes are not Disks Part 2: Logical Format • Disk block ~= Tape block • Disk volume ~= Tape extent Block aggregation operations apply to both Concatenate, stripe, mirror, etc.
• In OS/360-derived “mainframe” systems: Disk file ~= Tape file
• In open systems: Tape images usually used for packed files “archives”, “backups”, ~= file system
7
Copyright © 2002,2003 Storage Networking Industry Association
The SNIA shared storage model
8
File/record layer Database (dbms)
File system (FS)
Host Network
Block aggregation
Device
Storage Storage devices devices (disks, (disks, …) …)
Block layer
Copyright © 2002,2003 Storage Networking Industry Association
Services
Storage domain
Application
Tape in the SNIA shared storage model Storage domain 9
File/record layer Database (dbms)
File system (FS)
Tape-format system
Tape application (e.g. backup software)
Application
Host
Host Network
Block aggregation
Device
Storage Storage devices devices (disks, (disks, …) …)
Block layer
Copyright © 2002,2003 Storage Networking Industry Association
Sequential Network Extent Access Device aggregation
Tape Tape devices devices Tape Tape media media
Tape in the SNIA shared storage model
10
Tape application (e.g. backup software)
This packsFile/record files/records into layer tape extents/images.
Database File system (dbms) In open systems, (FS) all “host”resident functions take place in the tape application (e.g., backup software). Host Disk accesses Network can be random; Block tape is sequential; unit of Device aggregation aggregation is thus “extents”, not blocks This split is caused by
Storage devices (disks, …) Storage devices (disks, removable media (very…)
important for tape); removable Block layer disks (e.g., CD, DVD) could also be shown on disk side. Copyright © 2002,2003 Storage Networking Industry Association
Tape-format system
Storage domain
Application
Host
Sequential Network Extent Access Device aggregation
Tape Tape devices devices Tape Tape media media
Removable media: Significant functional impacts • Which tape is in the drive? What’s on it? Tape labels, indexes
• Where’s the tape I wanted? Catalogs, library slot management
• How do I get that tape into the drive?
Tape Tape devices devices Tape Tape media media
Operator instructions, robot commands Tape device could be a single drive or multi-drive library
• Can this drive read that tape? Different cartridge sizes and shapes Tape formats: significantly more diverse and complex than SD/DD/HD floppy formats 11
Copyright © 2002,2003 Storage Networking Industry Association
Backup techniques focus on: what is done • Three common Unix tape utilities tar – read the filesystem and write the tape dump – read the disk volume and write the tape dd – bulk copy from disk volume to tape
• Diagrams show data flows for backup Where the disk and tape are doesn’t matter Reverse the data flow arrows for restore
12
Copyright © 2002,2003 Storage Networking Industry Association
Backup technique: Files File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, tar)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 13
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Segment layer
Backup technique: File system volume File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, dump)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 14
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Segment layer
Backup technique: Volume copy to tape File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, dd)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 15
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Backup technique: Files to virtual tape File/record layer Database (dbms)
File system (FS)
Tape-format system
Backup software (e.g, tar)
Host
Block Block aggregation aggregation
Storage Storage devices devices (disks, (disks, …) …)
Block layer 16
Copyright © 2002,2003 Storage Networking Industry Association
Network
Extent aggregation
Device
Tape Tape devices devices Tape Tape media media
Backup architectures focus on: where it is done • Architecture is independent of backup technique • How does the data move to the tape(s)? Architecture examples focus on external tape libraries • External: on different system from backup software
See previous slides for internal tape • Internal: on same system as backup software
17
Copyright © 2002,2003 Storage Networking Industry Association
What’s in a tape library? • Tapes (media)
Tape library
And slots to store them
• Tape drive(s) Often more than one Independently usable
• Robot(s) Move tapes between drives and storage slots Independent command interface
• Robot command paths omitted from diagrams on following slides for clarity
18
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Direct-attach tape •• Direct-attach Direct-attach Tape Tape backup backup
Host with LVM
File/record layer
Backup software
Host block-aggregation
Block layer
Network block-aggregation
Device block-aggregation Disk array Tape library
19
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: LAN-attach tape Backup SW
•• LAN LAN Backup Backup
Host, no LVM
LAN
Host with LVM
File/record layer
Backup SW
Host block-aggregation
Block layer
Network block-aggregation
Device block-aggregation Disk array Tape library
20
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Shared tape drive LAN
Backup SW
LAN-Free LAN-Free Backup Backup Sequential Sequential sharing sharing of of same same tape tape drive drive
Host with LVM
Host with LVM
File/record layer
Backup SW
Host block-aggregation
Block layer
SN
Device block-aggregation Disk array Tape library
21
Network block-aggregation
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Partitioned tape library Backup SW
Host with LVM
Host with LVM
File/record layer
Backup SW
•• Multiple Multiple backups backups at the same at the same time time Robot, Robot, drive, drive, and and tape usage must tape usage must be be coordinated coordinated among among backups backups Host block-aggregation
Block layer
SN
Device block-aggregation Disk array Tape library
22
Network block-aggregation
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Virtual Tape Controller
Host with LVM
File/record layer
Backup Software
SN SN device device virtualizes virtualizes tapes, tapes, tape tape devices devices and/or and/or robots robots
Host block-aggregation
Block layer
Network block-aggregation Virtual Tape Controller Device block-aggregation Disk array Tape library
23
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Virtual Tape Controller + Disk cache Backup Software
Disk Disk used used as as cache cache •• Backup Backup to to Disk Disk
Host with LVM
File/record layer
•• Destage Destage to to Tape Tape
Host block-aggregation
Block layer
Network block-aggregation Virtual Tape Controller Device block-aggregation Disk array Tape library
24
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: Data movers for tape
Host with LVM
Host with LVM
File/record layer
Backup software
Server-Free Server-Free Backup Backup Backup Backup software software controls controls library library and and data movement data movement Command/control path
Block layer
Host block-aggregation
25
SN
Movement appliance
Network block-aggregation
Device block-aggregation Disk array
Movement appliance Tape library
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: File-server with tape drive File/record layer
Backup software Host
Host LAN
NAS system
NDMP NDMP Local Local Backup Backup Backup Backup software software uses uses NDMP NDMP to to control control data data movement movement and and tape tape Could Could use use NAS NAS head head instead of NAS system instead of NAS system
Host block-aggregation
Block layer
Network block-aggregation
26
Copyright © 2002,2003 Storage Networking Industry Association
Device block-aggregation
Backup architecture: File-server with external tape NDMP NDMP 3-Way 3-Way Backup Backup
File/record layer
Backup software Host
SN SN may may be be LAN LAN or or SAN SAN Backup Backup software software uses uses NDMP NDMP to to control control data data movement movement and and tape tape
bHost LAN
Could Could use use NAS NAS system system instead of NAS head instead of NAS head
NAS head
Block layer
Host block-aggregation Network block-aggregation
SN
Device block-aggregation Disk array Tape library
27
Copyright © 2002,2003 Storage Networking Industry Association
Backup architecture: File-server with data mover File/record layer
Backup software Host
NDMP NDMP 3-Way 3-Way Backup Backup Backup Backup software software uses uses NDMP NDMP to to control control data data movement movement and and tape tape
bHost LAN
Block Block commands commands issued issued to to movement appliance movement appliance
NAS head Host block-aggregation
Block layer
Network block-aggregation SN Movement appliance
Device block-aggregation
Disk array Tape library
28
Copyright © 2002,2003 Storage Networking Industry Association
Conclusions • Tape functionality addition to SNIA SSM Parallel functionality to existing disk-based model Backup is the motivating usage
• Open systems backup techniques What can be done E.g., Files (tar), filesystem (dump), device (dd)
• Open systems backup architectures Where it can be done Examples include LAN-free and Server-free backups Also NDMP backups of fileservers
29
Copyright © 2002,2003 Storage Networking Industry Association
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