What could be the rationale for purchasing a network storage / disk shelf?

Question

NAS

Dear colleagues.
There was an urgent need to supplement the justification for the purchase of the above equipment.
The rationale is now presented as follows:

Currently, in the "Management" backup of databases of subsystems /* Enumeration of information systems/* is performed once a week on the same servers where the main database is located. Such a backup organization does not allow storing copies of databases and documents for a long time. This can lead to the loss of important information in the event of a virus infection (backup information should not contain infected information), failure of the main storage media (hard drives), and also does not allow saving server and workstation software settings in backups. In 2013, the server /*So-and-so/*failed, resulting in 4 days of data loss. The period required for the resumption of the functioning of /*So-and-so/* was 5 working days.
In 2014, it is planned to purchase two backup systems (for general and closed circuits of the local network) with a total cost of 180-185 thousand rubles. The purchase of this equipment will ensure the possibility of reliable storage and quick recovery of information (databases, documents, programs, settings) in case of loss for any reason of a working copy of information.
The data storage system will protect against:
Damage to databases not related to the failure of hard drives
In the event of a virus infection, it will allow you to restore information from a copy that has not been in contact with infected machines.
It will allow you to store not only databases, but also software and operating system settings, which will reduce the time required to restore the system. In addition, more frequent backups will reduce the amount of data to be re-entered by the Office's specialists into the information systems databases.

If you have faced similar problems, please help. It is necessary to bring some calculations (economic justification or the like).
There is an idea to supplement the pluses with the fact that the presence of a network storage will allow to offload the disk subsystem of the main servers. But it won't be enough

Answer 1

The first thing to do is to make a backup plan with the terms
day, week, month, quarter, year,
calculate the information that needs to be stored within these terms + 30% for the growth of information,
say that you need redundant storage of information, this is a ride5 4 disks + hot spare
Say that the screw usb does not guarantee the operation of archives
, also report that the speed of saving archives and restoring under such conditions will be extremely low, which may lead to a simple organization

Answer 2

If, during downtime, a company loses money and valuable information, which is often more than 180 thousand rubles, then calculate the cost of downtime One hour (a day in your case). Although 5 days to restore performance, this should already have something to say to the management.

Answer 3

I'm also wondering - why not take a USB drive? :)
A disk shelf just for backups is somehow too romantic. To consolidate backups and move them beyond the limits of what is actually backed up, a dedicated backup server with large disks allocated for this is enough. And/or tape library. Or NAS storage, they are much cheaper.
Why do you need a disk shelf - for example, for virtualization, especially if fault tolerance and load balancing (HA and DRS) are expected. And even if it's not intended, the disk shelf gives you more flexibility to manage your virtual infrastructure. For single storage clusters (MSCS and others). For databases with a high load on the disk subsystem (an analysis of IOPS and Disk Queue is useful here), because more spindles - more IOPS.