Abstract: This paper outlines conventional disk-based backup and restore methods and the paradigm shift needed to keep up with escalating data growth, shrinking backup windows, overburdened IT Administrators, and overtaxed IT budgets. This paper will also detail how FalconStor Software® is
delivering the next level of backup and restore with revolutionary disk-based backup and restore services including new VirtualTape Library technology.
Reaching the Next Level
Introduction
In order to keep up with the explosive growth of data storage and to meet business
requirements for rapid-recovery, IT managers/administrators continue to search for alternative backup and restore methods that can facilitate:
1. High performance backup
2. Reliable backup, by eliminating media error and robotic failure 3. Rapid restore
4. Reduced operating cost (TCO)
5. Maximized return on investment (ROI)
In the Beginning
The first approach to the backup and restore process was very simple – the application server was directly connected to the tape drive, and it would back up its own disk(s) to a dedicated tape. This model worked well until the number of application servers reached double digits. The current approach to backup and restore was originally established based on the fact that each physical tape drive can support ONE backup or restore session at any given time. And, as the amount of data to be backed up increased, coupled with the business pressures of operating on a 24x7 basis became the norm, multiple tape drives/libraries would need to be purchased and deployed to accommodate concurrent backup and restore sessions!
Conventional Tape Backup Methods
Disk to Tape Backup in a LAN Environment – Conventional Backup of Local Disk
Figure-1
Disk to Tape Backup in a LAN Environment - Conventional Backup of Servers on the LAN
Disk to Tape Backup in a Fibre Channel SAN Environment
In a typical Fibre Channel (FC) SAN environment, the tape library is accessed by multiple backup servers. Since each tape drive can only be used by one backup server at a time, the backup servers need to coordinate the use of tape drives in the library to avoid conflicts. For example, Veritas backup products require the Shared Storage Option to coordinate access to tape libraries and tape drives in a FC SAN.
FalconStor’s Modular Solution Framework
The standardization of network storage protocols allows IPStor to provision virtual storage devices (disk, tape drive or tape library) to application hosts equipped using industry-standard interfaces such as Fibre Channel HBAs, iSCSI HBAs, or Network Interface Card (NICs).
IPStor – The Next Generation Storage Infrastructure
Fibre Channel and iSCSI SANs provide an efficient vehicle for IT managers to aggregate and provision disk or tape devices to application and/or backup hosts
SAN-based Backup
In the current backup model, the backup server relies on the remote backup agent to push the data from the application server over the IP-based LAN (see figure 2). This limits the speed of any single backup to the speed of the LAN. Since the speed of the LAN is often less than the optimal speed of the tape drive, backup applications often use interleaving or multiplexing to allow multiple backup agents to stream to the tape drive. While this does allow the tape drive to operate at its best speed, it requires that backups be coordinated across multiple application servers to provide the necessary data. It also has the unfortunate side-effect of actually increasing the time needed to restore data, since the backup application now needs to stream through multiple backup sessions to restore the data for the desired application server. And all the output of the backup agents adds to the workload of the LAN.
Given that many of the application servers are on the FC or iSCSI SAN, the easiest and most effective way to eliminate this bottleneck is to provide a SAN-based fast path to the backup server to access the application server’s disk(s) at the speed of the SAN (up to 2 GB/s). IPStor’s HyperTrac Backup option delivers a SAN-based fast path by:
Utilizing unique database-aware snapshot technology to capture a consistent image of the application host’s disk(s)
Provisioning the snapshot to the backup server over a FC or iSCSI SAN
Enabling the backup operation to take place without impacting the application server’s performance
IPStor HyperTrac
Leverages a SAN to Enable the Backup Server to Perform Zero-Impact, Server Free Backup and Restore Operations
Disk to Disk Backup
Given that the transfer rate of a FC disk array (e.g. CX200’s throughout is ~200 MB/s) exceeds the speed of a tape drive (e.g. LTO2’s top speed is ~70 MB/s with compression), backup software vendors are beginning to offer Disk to Disk or d2d backup options that utilize high-speed disk arrays to cache the backup data stream to:
Eliminate the tape drive as the bottleneck on the data path (if the backup software can stream the data faster than the maximum speed of the tape drive)
Accelerate the restore process if the tape session is already on disk
Disk-to-Disk-to-Tape (d2d2t) Backup Configuration
Using iSCSI or Fibre Channel Disk to Cache the Backup Stream Figure-6
IPStor’s network-centric architecture allows the IT managers to centralize the management and provision disk storage ‘on-demand’ (via the IPStor Capacity on Demand Option) to those backup servers (configured with the ‘backup to Disk’ option) over an iSCSI or FC SAN with minimal operating cost and optimal ROI.
The 3rd party backup vendor’s d2d option allows the IT manager to utilize the high-speed disk to cache/stage the backup stream provided the backup software’s throughput is greater the speed of the tape drive.
Disk-based Virtual Tape
While d2d backup offers an improvement over the current backup model, it requires reconfiguration of storage and provisioning of disk storage for caching.
The IPStor VTL (VirtualTape Library) solution utilizes disk to simulate the tape drive/library and therefore empowers IT managers to create and attach virtual tape drives and libraries to application and/or backup servers on a FC or iSCSI SAN as if they are physical tape drives/libraries, without incurring any additional material costs.
IPStor VTL – Delivers an Innovative, Open Solution Framework
The emulation of industry standard tape drives/libraries allows the backup products to interact with virtual tape drives/libraries in a seamless fashion without changing the existing backup configuration or policy.
And, in that each backup server can perform tape backup/restore to its dedicated tape drive/library, the VTL model also eliminates the need to share a tape drive among multiple backup servers on the SAN.
Disk to Tape Backup in a FC SAN Environment Using IPStor VTL
The following table outlines the costs associated with adding additional drives to an IT environment to meet backup requirements.
Storage Device Street Price
Capacity (GB/s)
Speed (MB/s)
$ Per Drive Native Compressed
Native
Compressed
DLT
$4,688
80
160
8
16
SDLT
$4,547
160
320
16
32
LTO-1
$5,850
100
200
15
30
LTO-2
$7,150
200
400
35
70
AIT-3
$2,700
100
260
12
31.2
SAIT
$10,000
500
1300
30
78
Tape
STK 9940
$39,500
200
400
30
70
Disk
Xserve
RAID
$10,990
3500
7000
400
400
By deploying the IPStor VTL solution, IT Managers can realize substantial cost savings.
Because IPStor VTL can provision industry standard virtual tape drives/libraries over the FC or IP network, it eliminates the need to purchase, install and maintain tape drives by presenting virtual tape drives/libraries to the backup server to meet current backup requirements and future growth.
In addition to reducing material costs, the IPStor VTL solution delivers a wide range of business benefits, including:
2) The ability to leverage the high transfer rate of state-of-the-art disk arrays to accelerate and aggregate the backup and restore throughput of existing backup servers. (See figure-9)
Throughput of IPStor VTL Appliance can be Scaled Upward
3) The ability to perform backups to a virtual tape drive/library connected to the backup server over IP (See figure-10).
Figure-9 Connecting to IPStor VTL Appliance over IP
Figure-10
IPStor VirtualTape Library Appliance offers four virtual tape drives/libraries to support four concurrent backup sessions.
4) The facilitation of tape vaulting by replicating disk-based virtual tape cartridges to the remote vault over IP. (See figure-11)
Replication between IPStor VTL Appliances over IP
5) The facilitation of tape vaulting by enabling the backup server to copy tapes to disk-based virtual tape cartridges in the vault. (See figure-12)
Tape Vaulting to IPStor VTL Appliance over IP
Figure-11
6) Enabling 3rd party backup software and industry standard NAS appliances (e.g. Network
Appliance filers) to perform backup and restore using the NDMP protocol over an IP network. (See figure-13)
NAS Appliance to IPStor VTL Appliance with NDMP Server over IP
7) Allowing service providers and corporate IT management to deploy virtual tape libraries at branch offices enabling data to be backed up on-site and then transferred to the main data center over IP.
Summary
While the current tape-based approach to backup has worked well, recent developments have made disk-based backup an attractive alternative. With higher speeds and greater flexibility, coupled with the current drop in disk prices, the time for disk-based backup has arrived.
FalconStor delivers a number of tools that make the transition to disk-based backup possible. From disk storage for use with backup applications d2d features, HyperTrac to provide
snapshots for SAN-based backup, and VirtualTape Library to make disk-based storage
accessible to all backup applications, IPStor provides the necessary framework to move backup to the next level.
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