EcrosTechWiki | NetworkStorage / Changing Needs

Our Need for Network Attached Storage

The basic reasons for us to have NAS on our home network haven’t changed all that much since Natasha was installed in 2008.

We’ve accumulated a lot of stuff that doesn’t need to be on the computers we use regularly, but that we want to be available if and when we need it. An example is the hard drive contents of computers that have been retired and replaced. Also, I have a habit of saving every program I download in case a newer version doesn’t work for me and I have to go back to an old one (at present, I have eight versions of Apache OpenOffice).
Having experienced a couple of computer failures (remember the capacitor plague?), we wanted, in a rather vague way, to have a second copy of some of the data that we used on a daily basis. An example is the Microsoft Money file containing our financial records.
Making routine backups of important work was becoming increasingly tedious using writable optical media.
Having also experienced a hard disk failure, if we were going to have some kind of centralized, shared storage, it should have some resistance to this and therefore use RAID technology to provide fault tolerance. (The NAS contains two disks and writes everything to both of them. If one of them totally fails, everything is still on the other. After replacing the failed disk, the NAS re-creates the redundant copy and you’re back to full protection.)

Originally, we took the attitude that this data would be, at worst, inconvenient to lose. If the house burned down, we figured we’d have more important things to worry about than what might have been stored on the Dell notebook that was bought in 2000 and failed in 2008. The NAS could be stolen and we’d still have copies of data that was also on our computers. Unless they were stolen as well. If the NAS failed, I could get another one and swap the disks over. Until D-Link discontinued it. Well, I could probably figure out how to get the data off some other way. Or could I?

Although I knew that I should really be looking into network attached storage again, I put it off until my wife forced the issue. She announced that she wanted an off-site backup of Natasha.

Updated Technology and Off-Site Backup

My objectives in replacing Natasha can be placed in two groups:

Using up-to-date storage technology, get rid of the annoyances listed on the History of Natasha page, i.e.
- With solid state drives (SSDs), rather than spinning rust, the NAS will get from the standby state to fully active in a few milliseconds, rather than seconds,
- SSDs also have higher read and write speeds and don’t need to seek (physically move the read/write head from track to track), leading to much faster data transfer, and
- Modern NAS devices have USB ports to which external drives can be attached, increasing the amount of storage presented to the network.
Put in place a more comprehensive backup procedure to protect our various types of data at the appropriate level. i.e.
- Make off-site backups of the data that my wife stores on the NAS, as instructed or at some regular interval (to facilitate this, I need to provide separate network drives for the other stuff stored on the NAS that does not need an off-site backup),
- Reduce the wake-up delay and increase the data transfer rate so that routine backups of our computers are free of tedium, and
- Provide second-tier storage for a lot of data that won’t be missed if it is lost.

A Hierarchy of Threats to Stored Data TO DO - complete this page

Failure of a computer. The drive(s) can be removed and connected to another computer to recover the data.
Failure of a data drive in a computer. A reasonably up-to-date copy (backup) of important data must have been made to storage external to the computer, for example, NAS. This isn’t quite as simple as it sounds. I have about 250 GB of storage used on my computer, only a few percent of which is stuff that I would be unhappy to lose. The rest is the operating system, installed programs, downloaded files, music ripped from my CDs and so on. I have these categories carefully separated out, but this is not how most people do things. Making periodic backups of 250 GB can easily edge back into the “tedious” and use up a great deal of storage.
Ransomware. The first defenses against this should be anti-malware software and cautious use of the Internet, but if it happens it can be dealt with in the same way a drive failure.
Accidental deletion or corruption of files (or data within otherwise intact files). You can try to ensure that this doesn’t happen by using reliable software and working carefully. If it does happen, then you can look for the missing files in your backup. But, what if you notice the problem some time after it happened? The last backup that contained the files may have been deleted. To combat this, it is possible to keep backups indefinitely (or, at least) for a long time, if you can reduce their size and/or provide enough storage.
The desire to recover prior versions of files, for example in software development. This would be dealt with by a version control system (I use QVCS) with the repository held on the NAS and included in the off-site backup (see below).
Theft or destruction of a computer. This can be dealt with in the same was as a drive failure, but you also need to buy a new computer.
Failure of a drive in the NAS. Assuming that the NAS uses RAID1, all you need to do is replace the failed drive. To address the problem of finding a replacement, you can make sure that the NAS will deal with dissimilar drives in a RAID pair or just buy a spare when you put the system together. SSDs have a projected lifespan that is related to data write/erase cycles rather than mechanical wear and the NAS should provide the means to monitor this, maybe even notifying you of drives nearing the end of their life.
Failure of the NAS. One would hope that a network attached storage device is built to high standards of reliability, but failure is always possible. If you can procure a compatible replacement, by which we mean one that can read the drives from the failed NAS, then you’re up and running again. Otherwise, see theft or destruction, below.
Theft or destruction of the NAS. In this scenario, you lose all data that is stored on the NAS but is not on any computer. This is where the need for an off-site backup arises. If you back up the entire contents of the NAS, you just buy a new NAS, retrieve your off-site backup (from the safe deposit box or a friend’s house) and copy over all the data. Now you are back to where you were when you made the backup (but not to where you were when the NAS was lost). Data that was only on the NAS and was added or changed after the backup was made is lost. This means that you should make off-site backups frequently, which is a problem because by their very nature they are inconvenient (unless your offsite storage is close by). You may partition data on the NAS into that which needs to be part of the off-site backup and the rest that would not be so bad if lost. This can reduce the size of the storage device you need and the time taken to make the backup.
Theft of all your houshold electronics. This is similar to just losing the NAS, above, but you only recover data that is on an off-site backup.
Natural (or man-made) disaster that destroys the house (fire, flood, earthquake, wind storm, war, terrorism, etc.). This can be dealt with in the same was as theft, but you also need to buy a new house.
Nuclear holocaust. This can be dealt with in the same was as house-destroying disasters, but you also need to find a new planet.