Compaq 108164-003 - ProLiant - 800 Technology Brief
Dds-3: enhancing dat reliability, capacity, and performance
Hide thumbs
Also See for 108164-003 - ProLiant - 800:
- Integration notes (52 pages) ,
- Technical manual (38 pages) ,
- White paper (30 pages)
Advertisement
Quick Links
'HFHPEHU
&RPSDT &RPSXWHU
&RUSRUDWLRQ
(&* 7HFKQRORJ\
&RPPXQLFDWLRQV
C
O N T E N T S
ECG036/1297
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
Mid-size businesses and branch offices using departmental servers with storage
. .
requirements of 24 GB or less and running Microsoft Windows NT
. .
. .
®
NetWare
3.x or IntranetWare
. .
. .
capacity, and reliable backup methods. Digital Data Storage-3 (DDS-3) technology,
. .
which is the recording format used by Digital Audio Tape (DAT) products, meets this
. .
. .
need with three times the capacity and twice the data transfer rate of DDS-2
. .
. .
technology and offers improved automated head cleaning mechanisms that enhance
. .
backup reliability. DDS-3 also provides low total cost of ownership for customers,
. .
. .
due to low-cost media and backward read/write compatibility with existing DDS-1
. .
. .
and DDS-2 media.
. .
. .
This brief discusses DDS-3 technology and the Compaq 12/24 gigabyte (GB) DAT
. .
. .
Drive, which is designed with DDS-3 technology.
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
. .
Please direct comments regarding this communication to the ECG Technology Communications Group at this
. .
. .
Internet address: TechCom@compaq.com
.
®
4.0 have a growing need for high performance, high
®
, Novell
Advertisement
Related Manuals for Compaq 108164-003 - ProLiant - 800
Summary of Contents for Compaq 108164-003 - ProLiant - 800
- Page 1 DDS-1 and DDS-2 media. This brief discusses DDS-3 technology and the Compaq 12/24 gigabyte (GB) DAT Drive, which is designed with DDS-3 technology. Please direct comments regarding this communication to the ECG Technology Communications Group at this Internet address: TechCom@compaq.com...
- Page 2 INTERRUPTION OR LOSS OF BUSINESS INFORMATION), EVEN IF COMPAQ HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. The limited warranties for Compaq products are exclusively set forth in the documentation accompanying such products. Nothing herein should be construed as constituting a further or additional warranty.
- Page 3 Compaq ProLiant 1200, ProLiant 1600, or ProLiant 2500 servers with storage requirements of 24 GB or less. To meet the needs of mid-size businesses, Compaq has an affordable line of DAT drives that use the DDS recording format and provide fast, reliable data storage.
- Page 4 Figure 3: Adjacent tracks are recorded at opposite angles, minimizing magnetic crosstalk. Compaq DAT Drive Product Line From the DDS format specification, Compaq developed a series of DAT drives using DDS technology, the first of which was the 2/4 GB DAT Drive (DDS-1), followed by the 4/8 GB DAT Drive (DDS-2).
- Page 5 A system with an “embedded” servo, as in the Compaq 2/4 GB DAT and 4/8 GB DAT drives, uses the automatic track following (ATF) method to ensure the tape head is in the center of the track being read. There are ATF areas embedded at the beginning and end of each track;...
- Page 6 The Compaq 12/24 GB DAT Drive does not use embedded servo tracking with ATF. Instead, it uses a timed tracking scheme that frees the ATF areas for user data, thus increasing the storage capacity.
- Page 7 (cont’d) Other ways DDS-3 technology increases track space are by compressing sub-code information into less space and by packing user data into fewer, larger blocks, thereby reducing total overhead for data blocks. As a result of the increased linear bit density, format efficiency, and increased use of track space, DDS-3 has three times the track space that DDS-2 has available for data storage instead of timing, sub-code, Reed-Solomon ECC, and block overhead (Table 1).
-
Page 8: Improved Reliability
(cont’d) DDS-3’s read-after-write (RAW) capability also improves the data transfer rate. RAW refers to the ability of a DDS drive to read and verify data immediately after it has been written. This is possible because of the extra set of read and write heads that DAT drives have. In the event of an error, the drive can rewrite the incorrect data repeatedly until it is read back successfully. - Page 9 From a practical standpoint, if a tape were used for a weekly backup, it should last for two years. However, because DDS cassettes are so inexpensive, Compaq recommends replacing them sooner to ensure a reliable backup.
- Page 10 Compaq performs extensive hardware and software testing to ensure a highly integrated and compatible solution for Compaq systems. Note: Please see the appendix for results of performance testing of the Compaq 12/24 GB DAT Drive. Figure 10: Compaq 12/24 GB DAT Drive being inserted into a ProLiant server.
- Page 11 ® Seagate Backup Exec for Microsoft Windows NT, Novell NetWare 3.x and IntranetWare 4.0 all support the Compaq 12/24 GB DAT Drive. The Seagate software complements the 12/24 GB DAT Drive with advanced industry features, such as: Intelligent disaster recovery...
- Page 12 SMART-2 Array Controller, fourteen 4.3 GB ultra-wide SCSI drives Operating system Microsoft Windows NT 4.0 Backup software Cheyenne ARCserve 6.0 (Build 516) Backup drive Compaq 12/24 GB DAT DAT drive firmware Version 2.86 Data set per drive 512 MB of 1 MB files RAIT level RAIT-0...
- Page 13 SMART-2 Array Controller, fourteen 4.3 GB ultra-wide SCSI drives Operating system Novell IntranetWare SMP Backup software Cheyenne ARCserve 6.1 Backup drive Compaq 12/24 GB DAT DAT drive firmware Version 2.86 Data set per drive 512 MB of 1 MB files RAIT level RAIT-0...
- Page 14 SCSI drives Operating system Novell IntranetWare SMP Backup software Seagate Backup Exec version 7.0 Rev. 554a Backup drive Compaq 12/24 GB DAT DAT drive firmware Version 2.86 Data set per drive 512 MB of 1 MB files RAIT level RAIT-0...