External drive for backing up NAS -- USB3 vs eSATA

[turnstyle]

It seems to me two drives in a NAS is more at-risk as compared to one drive in the NAS and one external drive.

I agree that mirrored drives are more problematical as compared to two separate volumes, synched at some specified time -- but it seems to me if I'm going to have two drives total, it seems it makes more sense to have one in the NAS, and one external to it.

For example, let's say there is a significant electric failure in the NAS, or some corruption of the NAS OS, etc.

If somebody is going to have two drives, do most here think it's better to have two drives in a 2-bay NAS? Or one drive in the NAS, and one drive external to the NAS?

Thanks, -Scott

 

[RMerlin]

If somebody is going to have two drives, do most here think it's better to have two drives in a 2-bay NAS? Or one drive in the NAS, and one drive external to the NAS?

Neither.

As the old mantra goes, a RAID is not a backup. Neither of the two scenarios here are "good enough". You want two drives in a RAID mirror to avoid complete loss of data in case of a hardware failure, and you want an external drive for backups in case of data loss/theft/data corruption.

 

[gatorback]

Don't forget that a disaster (fire, lightning, hurricane, flood) can wipeout a facility / building and that a backup site for important data in a very distant site (far enough so that the same hurricane is unlikely to wipe out the backup) is the better defense.

 

[sfx2000]

As the old mantra goes, a RAID is not a backup. Neither of the two scenarios here are "good enough". You want two drives in a RAID mirror to avoid complete loss of data in case of a hardware failure, and you want an external drive for backups in case of data loss/theft/data corruption.

Exactly - adopt a tiered strategy for backups, and always have a plan for emergencies - e.g. the bug-out plan, as you might not have time to grab everything...

The way to look at storage... my working files are on local machines, I rarely do live work on my NAS

Hot Storage - local working files

Warm Storage - for me this is TimeMachine on a local disk and a TimeCapsule

Cold Storage - Clones of disks to the NAS box, TimeMachine snapshots into another directory

Attic - the NAS gets backed up once a week over USB3 onto an NTFS drive - why USB3/NTFS - the NAS supports it, might be slow, but USB3 can be accessed by just about anything these days, and most platforms can at least read NTFS

Additionally, I have off-site live backup for certain mission/business critical files... and there's a lot of great services out there for that - Backblaze, Carbonite - I actually use something different which is rather expensive, but for my old business/consultancy, they have SLA's that are incredible for long-term data storage (on tape)...

 

[stevech]

Off-site... I'm using Adrive and OK with it. Not for drive images (too much data for my 5Mbps upstream), but for VIP and VVIP files. I encrypt my own sensitive files before uploading; with MY encryption software .

Adrive is $25/yr for 100GB. And it lets me backup from selected shares on my NAS (UNC pathnames). Most cloud services prohibit that.
Better than OpenDrive which I used to use.
The mass-marketed ones are way over-priced: Carbonite, Acronis cloud, Amazon Web Services + Rackspace, and many others.

 

[sfx2000]

Well, since we're talking about long-term backup - two USB3 drives, and adapters/cables in the computer bag - those drives have at the most 1 week old information - I have a couple of laptops, but one always has current info, and it's adapter is in the bag as well...

This is the bug-out plan if I need to evacuate on short notice, and I had to execute this about 4 months back - I live out in East San Diego County, in the foothills - e.g. Fire Country...

Leave the NAS, leave the desktops, have the computer bag staged, along with other important docs, and be ready to get out - I'm not going to wait 5 minutes for the NAS to do a clean shutdown (and yes, it can take that long), when I can just yank the USB drive, and take it, and it's peer and toss them in the bag and go... mainly because if I'm in bug-out mode, I've got other things to worry about, but with a staged backup, I can reconstruct after the fact with a fair amount of confidence...

 

[sfx2000]

So if I want to back the NAS up to an external, what do I use for the external?

Some empty enclosure with both eSATA and USB3?

If they're both eSATA and USB3, generally, in my experience with multiple protocol bridge converters, they'll perform at the lowest common denominator... depends on the chipset in the enclosure...

eSATA is fast... but USB3 - since this is your backup storage, is a better idea... one can walk into BestBug/Frys/BigBox store and get a low cost PC, and these days, most will support USB3...

 

[turnstyle]

I'm sorry, but I still don't get the point of the mirrored 2-bay NAS -- that is, assuming the NAS is being backed up to an external.

If the NAS and/or drive within it fails, I have the external right there.

(Additionally, I would try to cycle a second external off-site.)

I'm sorry if I'm being thick, but since there is a copy on an external drive right there, I don't really understand the value in ASLO having two drives in the NAS?

Thanks for the conversation.

 

[L&LD]

I'm sorry, but I still don't get the point of the mirrored 2-bay NAS -- that is, assuming the NAS is being backed up to an external.

If the NAS and/or drive within it fails, I have the external right there.

(Additionally, I would try to cycle a second external off-site.)

I'm sorry if I'm being thick, but since there is a copy on an external drive right there, I don't really understand the value in ASLO having two drives in the NAS?

Thanks for the conversation.

One drive is the files 'live'. One drive is a snapshot of the drives on a daily, weekly or monthly basis (or all, depending on the amount of data being copied).

The value in such a setup is no obvious. You work on the live data and have online backups available too (whether or not you have your offsite USB drive with you or not).

 

[turnstyle]

Right -- so if I have a NAS, and if I back it up to an external USB drive daily -- if the NAS fails, then I can restore from the USB drive -- so perhaps I lose a day.

With a two-bay NAS, if it's mirrored, and if one drive fails, then I don't lose that day -- but I still need to back up to an external. And it still seems to me that I could lose the whole NAS, in which case I still lose a day.

So it just seems the additional value of two drives in the NAS is pretty small (all assuming that I also back the NAS up to an external).

-Scott

 

[stevech]

I'm sorry, but I still don't get the point of the mirrored 2-bay NAS -- that is, assuming the NAS is being backed up to an external.

If the NAS and/or drive within it fails, I have the external right there.

(Additionally, I would try to cycle a second external off-site.)

I'm sorry if I'm being thick, but since there is a copy on an external drive right there, I don't really understand the value in ASLO having two drives in the NAS?

Thanks for the conversation.

You understand the difference between a 2-bay NAS that uses RAID mirroring, and a 2-bay NAS where the two drives are wholly independent volumes/file systems? Like two NTFS drives in a PC. Mirroring - I don't use because flaws, inadvertent deletions/human errors, corruption, etc., are instantly duplicated on the other mirrored drive.
A USB or eSATA external is needed for rather infrequent backups. Different story.

 

[turnstyle]

I would use the USB for regular backups of the NAS.

This strikes me as more fault-tolerant as compared to two volumes in a two-bay NAS, no?

With two drives in a single NAS, you still have a potential single point of failure.

Whereas a 1-bay NAS with an external drive has two totally independent copies.

 

[KenZ71]

I'll start by saying I am paranoid...

Running 3 x 2TB ZFS RaidZ2 which means I can lose 2 drives without data loss.

Why? Because I can. Also, if one drive fails my data is gone so I have the mirror. But while rebuilding the other two drives are under extra stress which can cause failures so that is why I do the 3 way mirror.

As for backup I have a 4th drive stored at work for off site storage with fire protection. Once a month I pull one drive, bring to work then bring the prior month home and rebuild the array, resilver in ZFS speak.

Been doing this for 5 years with used drives from ebay. Typically I outgrow before failure.

This is my system and it works for me.

 

[turnstyle]

Thanks -- but isn't your RAID itself then a potential single point of failure?

I don't mean to be doom-and-gloom, genuine question!

 

[stevech]

I would use the USB for regular backups of the NAS.

This strikes me as more fault-tolerant as compared to two volumes in a two-bay NAS, no?

With two drives in a single NAS, you still have a potential single point of failure.

Whereas a 1-bay NAS with an external drive has two totally independent copies.

I've repeatedly recommended a 2 bay NAS with two volumes AND a USB3 or eSATA for backup done rather infrequently.

 

[stevech]

Thanks -- but isn't your RAID itself then a potential single point of failure?

I don't mean to be doom-and-gloom, genuine question!

RAID helps protect from drive failure.
It does nothing for

• Theft
• Natural disaster
• Human error in NAS management or accidentally deleted folders/files
• Malware or file system corruption

REGARDING THIS THREAD
I think the horse is about dead.

 

[sfx2000]

Thanks -- but isn't your RAID itself then a potential single point of failure?

I don't mean to be doom-and-gloom, genuine question!

Interesting point - 1 volume, two drives, so the odds go up slightly...

Honestly though - you've asked the question, and got some great feedback... choice is up to you now.. we can't make that choice for you.

 

[turnstyle]

The reason I keep at it: as I understand it, one drive in a NAS backed up to an external drive -- that has to be be more fault tolerant than two drives in a NAS.

But people here seem to consider that an ill-advised solution, so I'm trying to understand if I'm missing something.

Obviously two mirrored drives in a NAS, which is also backed up to an external -- or two separate volumes in a NAS, which are backed up from one to the other, and then to an external -- obviously that's "even more" fault-tolerant -- but it costs three drives rather than two, and seems only marginally more fault-tolerant as compared to a single drive in a NAS backing up to an external drive.

I'm sorry if I seem thick or something -- but I'm genuinely confused why, for a two-drive solution, it doesn't make the most sense to have one drive in a NAS, and one external.

 

[RMerlin]

The reason I keep at it: as I understand it, one drive in a NAS backed up to an external drive -- that has to be be more fault tolerant than two drives in a NAS.

But people here seem to consider that an ill-advised solution, so I'm trying to understand if I'm missing something.

Obviously two mirrored drives in a NAS, which is also backed up to an external -- or two separate volumes in a NAS, which are backed up from one to the other, and then to an external -- obviously that's "even more" fault-tolerant -- but it costs three drives rather than two, and seems only marginally more fault-tolerant as compared to a single drive in a NAS backing up to an external drive.

I'm sorry if I seem thick or something -- but I'm genuinely confused why, for a two-drive solution, it doesn't make the most sense to have one drive in a NAS, and one external.

The arguments in favor of a NAS in a RAID 1 setup:

1) Uptime. If a drive fails, you can still keep doing whatever you were doing, until the time you get a replacement drive. So, there will be zero downtime. When there are more than one user accessing the data, this can be important, otherwise you'd have to move the USB backup disk around, or share it from a PC and spend time configuring its access.

2) Zero data loss in case of a HW failure. If a single drive fails, you lose everything that was changed since the last backup, which can be anywhere between the previous day (in case of daily backups) or a week, or even more if you do it less frequently. With a RAID, if a disk fails, you lose absolutely zero data.

3) Ease of upgrade. Some NAS lets you do in-place upgrades to bigger disks without the need to backup and recopy everything to a new disk.

4) General HW quality. A two disks NAS is often higher quality than a cheap single disk network-attached enclosure.

This is why a two disks total solution isn't ideal. You need three disks for that if you really want to cover everything. And considering the price of disks today, it's not that expensive. Put two quality disks in the NAS, and go with a cheaper, high capacity USB3 disk for backups.

Never skimp when it comes to your data security. Hard disks are critical components, as a failure can be catastrophic.

If you still want to go with a one disk NAS + one external disk setup for economical reasons, those benefits are what you will have to give up in such a setup.

 

[L&LD]

Seems we can't get our points across to turnstyle in a way he / she understands?

In addition to agreeing with RMerlin and what I've previously posted, the following is also a suggestion to my customers too.

Buy two identical (1 or 2 bay) NAS' and have the main one backup to the other (rsync) on a daily, weekly or monthly schedule (depending on how quickly you accumulate new or changed data). Yes; much higher cost. But now you have the start of a true backup (data and hardware) if the risk or cost of downtime is that important.

I do not suggest 1 or 2 bay NAS units if the budget is available. 4 bay and higher are usually the better long term solution (for the reasons RMerlin stated).