RAID Question

Both give you the same single write speed and double read speed, plus the same capacity. However, RAID 6 gives you recovery from the failure of ANY two drives, while RAID 1 can't recover from a double drive failure of same pair.

On the other hand, if you suffer a hardware failure, RAID 1 drives will likely be readable, individually, in any machine, while RAID 6 may require at least two drives and the *SAME* model RAID controller or software.

I think its time for the old adage. RAID is not a backup solution, It is an *availability* solution

If you want to *preserve* data against drive failure, back it up on another drive. If you want it *available* with a drive failure, use RAID. And be prepared for it being unreadable if a controller fails.

Surely for backup systems speed doesn't really matter does it? At least not for small 'home' systems. My backups run overnight and even if they took an hour (which they don't) it wouldn't matter in the slightest.

In general I avoid RAID, it seems to add complexity (and thus likelihood of failure) without actually gaining much. I simply duplicate my important backups to different drives in different pieces of hardware (which are also in different buildings). If any one backup fails completely I still have the other backup and of course the original.

Indeed.

The question is what you're going to do when the first RAID1 drive fails. If you keep a spare drive around, you might just plug it in (or keep it as a hot spare). If you don't, you may have to order a drive and wait for it to be delivered - at that point you have no protection from another drive failing.

The subsequent problem is that rebuilding onto the new drive is going to put additional stress on the other drives (they're all working much harder than normal during the rebuild), so the risk of a second drive failing becomes elevated. Then you're screwed.

If you go to RAID6 then losing the first drive means you still have some protection if another drive happens to croak during the rebuild. Or if you do something dumb like pull a working drive instead of the broken one.

However if drive failures are correlated (bad PSU, dodgy SATA controller, mains spike, bad batch, bad firmware) then you're screwed anyway.

Theo

ok...

(there are also things like plex server that you can run on it - although upgrade the RAM to 8GB if you do)

QNAP boxen usually support ling aggregation - so if your switch is up to it, you can get more than 1 x gig ethernet total throughput out of it (but not to the same endpoint if that is a single gig ethernet connection).

With 4 drives, then RAID 5, 6 or 10 are your best options.

6 Is slower but will allow any two drives to fail. So a better fit for your use case.

The advantage (to me) of the Nvidia Shield is if I feed it an iso file it presents it as a DVD with the full menu and whatever resolution the original DVD was.

It is!

I decided to go for RAID 6 in the end, it's copying data over as I type.

Thanks to everybody for the input :-)

I have a lot of empathy with Chris Green's comment that the best thing is to avoid RAID. 4 TB is plenty of capacity for my needs so I will think that through.

I run my DVDs etc through handbrake and reduce them down to a single video file - saves space and makes them more portable etc (can extract most of the "extras" to other files if wanted)

for a backup role, that is probably a good choice.

RAID has its place, just don't think of it as proper "backup" in isolation (although in part of a bigger scheme it can be a part of it)

I did that as well, I currently have several zonka bytes of video files in my archive!

I have unwrapped it to 4 x single 4 TB drives, the data is copying over to volume 1, video will follow. The TS451 will be set up to keep the 4 drives in sync!

I simply don't have the facilities to back up all of my data, but I'm not going to be too bothered if my recorded TV collection is lost or I need to re-rip my CDs and DVDs that are currently stored away. RAID helps reduce the risk of a drive failure making me have to start again.

I can and do back up all the important stuff (family photos, work records, emails, other documents) locally - alternating a couple of 3TB drives - and my son backs up those same files, via my VPN, to spare space on his home server.

Similarly, his important files are backed up to our home server.

If you really want disaster recovery you need your data in two places.

I keep a backup of my important stuff in a drive in my bedside drawer. The machine lives in my garden office. It would take a lot to destroy both buildings.

Andy

Back in the '90s, I worked for an Engineering company. They backed up their computers to their other offices. That meant that they had backups on four different CONTINENTS. About as safe as is possible.

Enter Putin stage left and Trump stage right....

my back up is in Switzerland ;-)

In which case data security will be the least of your problems

It doesn't matter what solution to data back up is proposed someone will always come along & say "But what if ......"

This has been around for a good many years:

To which the correct answer is 'then data loss is the least of your worries..

Thomas Prufer

Beat me to it:-)