How many D800e RAW files will fit on a 1TB external hard drive?

Started Apr 8, 2013 | Questions thread
GVansteelant
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Re: How many D800e RAW files will fit on a 1TB external hard drive?
In reply to AofA, Apr 9, 2013

You want both RAID (for security and speed) and backup (when the sh*t hits the fan).

As nobody else seems to want to explain it, I'll give the different RAID levels a try.

RAID level 0 (or RAID 0) is the simplest form of RAID array and contains at least 2 HDD which are mirrored. This means data is written to both drives concurrently so you have an exact copy in case one of the drives fails. You do not get a speed improvement when writing (can even cause a slight decrease in write speed)  but you get a small increase in read speed because the data is read from the 2 drives concurrently. The capacity of your RAID 0 is equal to the capacity of your smalles drive in the set. 2 identical drives is preferred but not necessary with most modern hardware or software solutions.

RAID 1 contains at least 2 drives which are striped. This means the data is spread accross the 2 drives which results in an increase in read and write speeds. Of course, if one of the drives fails, you're f*cked and your data is gone. The capacity of your RAID 1 is twice the capacity of your smallest drive in the set. 2 identical drives is preferred but not necessary with most modern hardware or software solutions.

Then there are a whole bunch of higher RAID levels which try to combine the pros of RAID 1 and RAID 2. RAID 5 for example, uses at least 3 drives with an extra drive to store parity data to be able to reconstruct your data in case a drive fails. You get great speed and only loose 30% capacity in stead of 50% for security.

Personally, I use 4 x 1 TB HD in my MacPro configured in RAID 10: a stripe of mirrors. This gives me 2 TB of data, great speed and security but I loose 50% capacity. I use SoftRAID to configure the RAID array but the built in OSX Disk Utility RAID (which is developed by SoftRAID btw) works almost as good (just a little less options and monitoring).

Now all the above is just as easily configured in an external setup (be it Thunderbolt or USB 3.0) and also works with the OSX built in RAID software (limited to RAID 0, RAID 1 or RAID 10 with sufficient hard disks). Note: never configure a RAID 01 (mirror of stripes) as this will not give you the required robustness in case of a HDD failure).

Why is the above not enough? Because, as pointed out by another member above, the RAID does not protect you against accidental damage or deletion of a file. For that you need a backup and a good backup not only copies the files to a different location (can be on the same site or off-site) but also makes copies over time. And there's where TimeMachine comes into the picture. TimeMachine makes copies of your data every hour for the last day, Every day for the last week and every week for eternity or until your backup volume runs out of space. This is repeated every hour and the whole schedule is updated. Pretty complicated if you wanted to do it yourself but TimeMachine takes care of all the headache and works seamlessly behind the scenes. With OSX 10.8 (and later), you can even define different volumes as backup volumes and TimeMachine will alternate between them to spread the risk even further.

As icing on the cake, I also have a BackBlaze account which makes a backup of my files to an offline server farm in the cloud. This is so I can sleep easier and know my photos will survive a fire or meteor strike on the house (even if I don't). Of course restoring from this cloud based backup is OK for a few files but becomes cumbersome for larger collections (it took a few weeks for the first backup to finish). BackBlaze offers to send you your files on USB thumbdrive or USB HDD if the size of the restore is too large but this will cost you extra. Still, a small price to pay if you really need it.

Hope this helps.

Regarding your original question about the number of pictures or amount of video you can fit on 1TB of HDD space, who cares? It all depends on the quality selected and subjects shot and HDD are cheap. Not as cheap as they were before the Thailand flooding but the prices are getting better again. By the time you fill up your drives, just buy some more...

Cheers

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