Electro-magnetic storage (magnetic tape disk) exist for over 50 years with excellent performance for sequential work load.
Imagine, if you have a book without index. if something at page no 30 which you are you looking for , you have to scan from first page to till the item not found. And when you reach at page no 30 then you know about actual content and your search stopped. Similarly electro-magnetic tape disk is used for sequential access , its not possible to read randomly, meaning that not suitable for random read workload.
Magnetic tape is used for secondary non-volatile memory, persistent memory and this is specially design for low frequent access data. when you talked about low frequently access data , it mean frequency of reading is very low and not expecting to retrieve very fast. Now question is which type of activity can be considered as low frequency access data for say
- backup activities: when you taking backup your frequency of access of data is very low , perhaps once in week or once in a month.
- archival activities: When you archive the data from daily transactional database, your expectation is not to retrieve the data as like transactional.
Electro-Magnetic storage is well known, because :
- for existence for over 50 years
- for excellent performance for sequential workload
Key points of magnetic tape drive
- Existing for over 50 years: You know magnetic tape is well known for taking backup of huge amount of data for over 50 yers.
- Excellent performance for sequential work load: excellent performance for sequential workload for taking backup or archival sort of data. not prefferable for random workload.
- storage space & Size: Relatively permanent and holds large quantities of data
- Performance: it is well suited for sequential access of data ( sequential workload). not suitable for random access of data (random workload). if you have to read random workload , it involves multiple fast-forward and rwind operation which is not preferrable. Its not suitable for multiple fast-forward and rewind opration. 1000 times slower than disk
- Speed: excellent speed with sequential workload but not good for random workload. 1000 times slower than disk if you compare with random workload
- Usage: mainly used for backup, archival of dat , you can say storage of infrequently-used data
- Cost: low cost if you compare with HDD or SSD. consequently 1000 times slower than disk
- Common technologies are 4mm, 8mm, 19mm, LTO-2 and SDLT
- the original version of which was released in 2000 and can hold 100 GB of data
- The seventh generation of LTO Ultrium was released in 2015 and can hold 6.0 TB
Your comments are welcome to improve this post about magnetic tape drive. Happy learning 🙂