From ce64e9b1c49cd94733a18768a733cdf149fa7ddf Mon Sep 17 00:00:00 2001 From: Nik Clayton Date: Tue, 26 Oct 1999 21:39:59 +0000 Subject: [PATCH] Additional information about DDS-3, 8mm, DLT, and AIT capacities. Prose is a little stilted, which is my fault. This section really needs rewriting with tables of tape types, capacities, and so on, which would present the information much more intuitively. Submitted by: Adam Steffes --- .../books/handbook/backups/chapter.sgml | 30 ++++++++++++++++++- .../books/handbook/backups/chapter.sgml | 30 ++++++++++++++++++- 2 files changed, 58 insertions(+), 2 deletions(-) diff --git a/en_US.ISO8859-1/books/handbook/backups/chapter.sgml b/en_US.ISO8859-1/books/handbook/backups/chapter.sgml index a3f1582f97..6a805f7ec4 100644 --- a/en_US.ISO8859-1/books/handbook/backups/chapter.sgml +++ b/en_US.ISO8859-1/books/handbook/backups/chapter.sgml @@ -1,7 +1,7 @@ @@ -55,6 +55,9 @@ drives in a single cabinet with automatic tape changing. Library capacities reach 240 GB. + The DDS-3 standard now supports tape capacities up to 12GB (or + 24GB compressed). + 4mm drives, like 8mm drives, use helical-scan. All the benefits and drawbacks of helical-scan apply to both 4mm and 8mm drives. @@ -79,6 +82,10 @@ with 6 drives and 120 tapes in a single cabinet. Tapes are changed automatically by the unit. Library capacities reach 840+ GB. + The Exabyte “Mammoth” model supports 12GB on one tape + (24MB with compression) and costs approximately twice as much as + conventional tape drives. + Data is recorded onto the tape using helical-scan, the heads are positioned at an angle to the media (approximately 6 degrees). The tape wraps around 270 degrees of the spool that holds the heads. The @@ -150,12 +157,33 @@ tapes over 1 to 20 drives, providing from 50GB to 9TB of storage. + With compression, DLT Type IV format supports up to 70GB + capacity. + Data is recorded onto the tape in tracks parallel to the direction of travel (just like QIC tapes). Two tracks are written at once. Read/write head lifetimes are relatively long; once the tape stops moving, there is no relative motion between the heads and the tape. + + + AIT + + AIT is a new format from Sony, and can hold up to 50GB (with + compression) per tape. The tapes contain memory chips which retain an + index of the tape's contents. This index can be rapidly read by the + tape drive to determine the position of files on the tape, instead of + the several minutes that would be required for other tapes. Software + such as SAMS:Alexandria can operate forty or more AIT tape libraries, + communicating directly with the tape's memory chip to display the + contents on screen, determine what files where backed up to which + tape, locate the correct tape, load it, and restore the data from the + tape. + + Libraries like this cost in the region of $20,000, pricing them a + little out of the hobbyist market. + Using a new tape for the first time diff --git a/en_US.ISO_8859-1/books/handbook/backups/chapter.sgml b/en_US.ISO_8859-1/books/handbook/backups/chapter.sgml index a3f1582f97..6a805f7ec4 100644 --- a/en_US.ISO_8859-1/books/handbook/backups/chapter.sgml +++ b/en_US.ISO_8859-1/books/handbook/backups/chapter.sgml @@ -1,7 +1,7 @@ @@ -55,6 +55,9 @@ drives in a single cabinet with automatic tape changing. Library capacities reach 240 GB. + The DDS-3 standard now supports tape capacities up to 12GB (or + 24GB compressed). + 4mm drives, like 8mm drives, use helical-scan. All the benefits and drawbacks of helical-scan apply to both 4mm and 8mm drives. @@ -79,6 +82,10 @@ with 6 drives and 120 tapes in a single cabinet. Tapes are changed automatically by the unit. Library capacities reach 840+ GB. + The Exabyte “Mammoth” model supports 12GB on one tape + (24MB with compression) and costs approximately twice as much as + conventional tape drives. + Data is recorded onto the tape using helical-scan, the heads are positioned at an angle to the media (approximately 6 degrees). The tape wraps around 270 degrees of the spool that holds the heads. The @@ -150,12 +157,33 @@ tapes over 1 to 20 drives, providing from 50GB to 9TB of storage. + With compression, DLT Type IV format supports up to 70GB + capacity. + Data is recorded onto the tape in tracks parallel to the direction of travel (just like QIC tapes). Two tracks are written at once. Read/write head lifetimes are relatively long; once the tape stops moving, there is no relative motion between the heads and the tape. + + + AIT + + AIT is a new format from Sony, and can hold up to 50GB (with + compression) per tape. The tapes contain memory chips which retain an + index of the tape's contents. This index can be rapidly read by the + tape drive to determine the position of files on the tape, instead of + the several minutes that would be required for other tapes. Software + such as SAMS:Alexandria can operate forty or more AIT tape libraries, + communicating directly with the tape's memory chip to display the + contents on screen, determine what files where backed up to which + tape, locate the correct tape, load it, and restore the data from the + tape. + + Libraries like this cost in the region of $20,000, pricing them a + little out of the hobbyist market. + Using a new tape for the first time