Media Systems: Incorporating the TV and the HiFi - Smart Home Automation with Linux and Raspberry Pi - page 93

So, clearly, if you want a NAS to store DVD images, you will need a filesystem that can support 4.7GB files.
This usually means FAT-based systems are inadequate or that you will have to remove the DVD menus and reencode
the movies into an alternative (and smaller) format.
The recover question is slightly more involved. If you ever have to remove the hard disk from its NAS mounting
and place it in a standard PC to recover the data, you will need a PC that is able to read whatever filesystem is used
by the NAS.
NTFS fares slightly better in the Linux compatibility stakes, but not much. Although it's possible to read NTFS
partitions under Linux, writing back to them is considered dangerous, although there are two open source drivers
(Captive NTFS and NTFS-3G) that do support it. Additionally, there is a commercial driver (NTFS for Linux, from
Paragon) that solves the same problem. For basic recovery, a read-only disc is fine, although you won't be able to
repair the disk without reformatting it, for the most part.
The natural solution is to use ext2 for any and all NAS drives, because this has the widest support in the Linux
world. Many NAS devices now support this, so it can be worth spending a little more to get one because it ticks all the
boxes. If your main desktop machine at home is Windows, then there are even ext2 recovery tools for Windows such
as Linux Recovery from DiskInternals.
The type of data you're storing will determine the type of backup plan you need. When this is personal data,
such as letters or photographs, then consider a NAS featuring built-in RAID functionality. These often autoconfigure
themselves when a second drive is plugged in, so be warned if you insert a used drive thinking you'll gain extra space!
Several types of RAID configuration are available, but the most common in this case is RAID-1, which uses a second
drive to make identical copies of anything written to the first. It does this automatically and transparently from the
user, so should either drive fail, the other can be used to recover the data. You should always remember, however,
that RAID isn't a backup! It just makes it a bit less likely that you'll lose data to disk failure. It won't protect against
corruption from controller failures, fire, flood, or theft.

N Using hardware RAID solutions is a double-edged sword for some system administrators. They work
seamlessly and take no effort to set up and maintain. However, if the RAID system has a problem and uses a custom disk
format, then it might be impossible to recover the data on the disk. You can solve this by buying two pieces of hardware
and verifying that you can swap the disks without a problem before they are put into active service. Alternatively, you can
check with the manufacturer that the disk format used either is known or comes with suitable software recovery tools.

Note

Backing up data, such as DVD or music rips, doesn't (and shouldn't) require RAID—although having one does
no harm. Because this type of data changes less frequently, you can make do with an external USB hard drive plugged
into your desktop machine. You can then run the backup software of your choice (see Chapter 6 for some possibilities
here) to copy only those files that have changed and then unplug and store the drive. This prolongs the life of the drive
and is worth the extra effort.
As with all backups, they are useless unless tested regularly, so make sure that you do test them. Some people will
test them by copying their backups to a new drive every 6 to 12 months. The cost is negligible, compared to the many
hours spent ripping and organizing the data. Furthermore, the price per gigabyte comes down every year, allowing
you store more data in a smaller form factor. If you are desperate for extra space, you can then reuse the older drive
elsewhere in your system. Although tape backup systems are a favorite of most businesses, the cost and convenience
of USB hard drives render them unnecessary for the home market.

N Hard drives either fail in the first few weeks or the day before you remember to back up. Therefore, when
buying disks, always buy from different manufacturers and at different times, so if you get one disk from a bad batch
(IBM Death Star, hang your head!), you minimize your chances of getting two.

Note