External drive for backing up NAS -- USB3 vs eSATA

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turnstyle

Regular Contributor
Hi all,

I've been looking into getting my first NAS -- it'll probably be a single-bay, holding 4-6TB -- or if I get a 2-bay, it'll probably start off with a single 4-6TB drive.

I also plan on getting an external 4-6TB drive to back the NAS up to (in fact, I hope to get two of them, so that I can cycle one off-site.)

I assume an external with eSATA would be preferable, but they're hard to find.

I lean toward something like the WD My Book for the external -- but they don't come with eSATA, and overall there seem to be very few options for eSATA drives.

Is it better to just get the WD My Book and stick to USB3? Or should I be looking at empty enclosures with both USB3 and eSATA ports? Or am I missing a sensible off-the-shelf drive?

Thanks for any pointers, -Scott
 

RMerlin

Asuswrt-Merlin dev
I prefer USB3. The connector is more rugged than eSata, and USB3 is less likely to fade away in the future than eSata. So, you will always be able to plug back the disk on a desktop or a laptop to recover its content in case of a NAS failure. eSata support is increasingly rare on desktop, and very rare on laptops.

Performance-wise, the two will be pretty similar.
 

turnstyle

Regular Contributor
I was thinking the external drive would ideally have *both* eSATA *and* USB3 -- so, with a NAS that has an eSATA port, I can get the benefit -- but I could always fall back to USB3 if I need to move the external drive to a computer/laptop.

You think USB3 and eSATA are pretty similar? (Does that still hold for lots of small files, or mostly a handful of big files?)

Thanks again, -Scott
 

sfx2000

Part of the Furniture
Both sSATA and USB3 bring unique advantages to the table - eSATA is focused on storage, whereas USB3 is everything else and storage..

I would agree with RMerlin - USB's advantage is that most, if not all, computers have USB ports...

It's kinda like Display Port vs. HDMI for graphics... (FWIW, my work laptop, Thinkpad, has both Display Port and eSATA - go figure...)
 

stevech

Part of the Furniture
eSATA is faster than USB3 by far. But it's not present for may NASes. And eSATA seems to be in decline of popularity.
 

sfx2000

Part of the Furniture
eSATA is faster than USB3 by far. But it's not present for may NASes. And eSATA seems to be in decline of popularity.

Not that much different than Firewire or Thunderbolt - these are excellent interfaces, just like eSATA...

DisplayPort is far more flexible than HDMI, but like USB3, HDMI is good enough...

And good enough sells, eh?
 

turnstyle

Regular Contributor
For example, I'm looking at NAS'es such as the Synology DS115, DS215j and QNAP TS-131.

I really only need one bay, which I would back up to the external drive.

The Synology DS115 and QNAP TS-131 both include eSATA.

However the DS215j seems to have the same specs as the DS115 -- except the DS215j has two bays, but no eSATA (and is only about $20 more than the DS115).

So, for example, if I get the DS115 rather than the DS215j, then it seems I SHOULD be using the eSATA -- if I'm not going to use the eSATA, then it kind of seems silly to get the DS115 rather than the DS215j, right?

Thanks!
 

RMerlin

Asuswrt-Merlin dev
eSATA is faster than USB3 by far.

Not really. Even from the raw bandwidth level, it's a 5 Gbps USB 3.0 vs a 3 Gbps eSata (those are rarely 6 Gbps). And from a real life situation, both are much faster than your average SATA HDD that will peak at about 100-120 MB/s, so the bottleneck remains the HDD. You only lose a bit of throughput with USB 3.0 due to protocol overhead, but it's nowhere "by far".
 

turnstyle

Regular Contributor
Isn't the benefit of eSATA over USB3 going to be more prominent with lots of little files, rather than a big file?

And, for example, if a backup program is doing tens of thousands of compares to determine which files need to be copied over, doesn't that come under the "lots of little files" category (even if they don't actually need to be copied)?

THX!
 

sfx2000

Part of the Furniture
I think the big benefit of eSATA would be if someone had an external RAID chassis perhaps - single disk won't make a difference between USB3 and eSATA for the most part (unless that disk is really, really fast like an SSD).

Remember with copies with many small files vs. a few large - it's really the filesystem overhead of both the source and the destination that is the limit, plus some SMB/AFP general overhead as well...
 

turnstyle

Regular Contributor
But isn't there a "USB per file" hit each time the NAS accesses a file on an external USB drive that there wouldn't be if the external drive were eSATA?
 

stevech

Part of the Furniture
For example, I'm looking at NAS'es such as the Synology DS115, DS215j and QNAP TS-131.

I really only need one bay, which I would back up to the external drive.

The Synology DS115 and QNAP TS-131 both include eSATA.

However the DS215j seems to have the same specs as the DS115 -- except the DS215j has two bays, but no eSATA (and is only about $20 more than the DS115).

So, for example, if I get the DS115 rather than the DS215j, then it seems I SHOULD be using the eSATA -- if I'm not going to use the eSATA, then it kind of seems silly to get the DS115 rather than the DS215j, right?

Thanks!
I urge you to get a 2 bay and run two volumes, with the automatic backup scheduled for once a day. An external eSATA/USB3 drive is good for meeting the backup philosophy of 3-2-1, but if you are like me, USB3 backups are not auto-scheduled (run manually), due to the desire to keep the drive out of thieves' sight, and that not all eSATA/USB3 enclosures spin-down with inactivity.
 

stevech

Part of the Furniture
But isn't there a "USB per file" hit each time the NAS accesses a file on an external USB drive that there wouldn't be if the external drive were eSATA?
USB will have more overhead that eSATA, but it's not a decision driver. My own experience, with ext4 file systems (NTFS on a NAS is slow due to Linux drivers), is that USB3 is significantly slower that eSATA but eSATA cables are a PITA to handle if you routinely disconnect the drive to hide it.
 

turnstyle

Regular Contributor
Thanks, twice, with comments below...

I urge you to get a 2 bay and run two volumes, with the automatic backup scheduled for once a day. An external eSATA/USB3 drive is good for meeting the backup philosophy of 3-2-1, but if you are like me, USB3 backups are not auto-scheduled (run manually), due to the desire to keep the drive out of thieves' sight, and that not all eSATA/USB3 enclosures spin-down with inactivity.

This is for my home, so I'm not worried about somebody walking off with an external drive -- in fact, I see ease of walking off as a *feature* (because I hope to get into the habit of cycling a copy off site).

I don't really see a need for two bays (for my use). As I'm envisioning it, I would get a 4-6TB drive for the NAS, and a 4-6TB external. I'm totally open to being reeducated, but I can't really see a need for the second bay (provided I'm backing up to the external). And if I had a 2-bay with mirrored drives, it seems I still need the external.


USB will have more overhead that eSATA, but it's not a decision driver. My own experience, with ext4 file systems (NTFS on a NAS is slow due to Linux drivers), is that USB3 is significantly slower that eSATA but eSATA cables are a PITA to handle if you routinely disconnect the drive to hide it.

I had been planning on using NTFS for easier access in an emergency -- NTFS is slow compared to EXT4 on these NASes?

As soon as I think I have a handle on making a smart decision, everything changes! :)
 

sfx2000

Part of the Furniture
But isn't there a "USB per file" hit each time the NAS accesses a file on an external USB drive that there wouldn't be if the external drive were eSATA?

I think a lot of it would depend on the particular drive in use... and also on the enclosure's USB implementation (USB to SATA, whether it's IDE emulation or AHCI, certain SATA features that might make a difference like native command queueing, etc...)
 

stevech

Part of the Furniture
... This is for my home, so I'm not worried about somebody walking off with an external drive -- in fact, I see ease of walking off as a *feature* (because I hope to get into the habit of cycling a copy off site).
I know several people who had all their quickly-grabbed PC equipment burglarized from their homes.
 
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turnstyle

Regular Contributor
I know several people who had all their quickly-grabbed PC equipment burglarized from their homes.

But I'm still going to need an external drive to back up the NAS. (Right?) So I don't get the point of two drives in the NAS, given that 4-6TB is plenty for me.

So I thought: if the NAS has eSATA, shouldn't I be looking for an external with eSATA (in addition to USB3). I thought the answer should be an obvious "yes" -- but there doesn't seem to be an off-the-shelf drive, like the WD with USB3.

When you have a 2-bay NAS, with two non-mirrored drives -- do you back that up to some USB enclosure that mounts two drives?
 

claykin

Very Senior Member
eSata passes harddisk SMART data, USB does not.

Ever try to perform data recovery on a usb harddisk? Its difficult and most cases you have to remove the disk from the container and connect using Sata to have a decent chance of recovering data.

I wouldn't recommend many WDC USB external disks. For a while now, WDC has chosen to add the Sata -> USB bridge chip directly on the harddisk's motherboard. So, many of the disks they use in externals only have a USB connector. No Sata. This means good luck recovering data.
 

turnstyle

Regular Contributor
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?
 

stevech

Part of the Furniture
But I'm still going to need an external drive to back up the NAS. (Right?) So I don't get the point of two drives in the NAS, given that 4-6TB is plenty for me.

So I thought: if the NAS has eSATA, shouldn't I be looking for an external with eSATA (in addition to USB3). I thought the answer should be an obvious "yes" -- but there doesn't seem to be an off-the-shelf drive, like the WD with USB3.

When you have a 2-bay NAS, with two non-mirrored drives -- do you back that up to some USB enclosure that mounts two drives?
My 2 bay has two independent volumes - so that if the file system on the main drive becomes corrupt, the other drive's file system is likely not. The 2nd drive gets a copy of important foldres once a day. Automated. MUST be automated, not MANUALLY done.

Also, if a human error in deleting files, or misconfiguring a NAS utility occurs, or something like that, the 2nd drive's file system still has it. With RAID and mirroring, there's no protection from these two and other examples.

The external drive backup is to protect from theft of NAS (external drive is out of sight, secured).

On the 2nd volume, I also have the Time Backup utility copy and keep the last x months of all file versions, for selected VIP folder trees. (Synology calls this Time Backup; QNAP doesn't have similar - theirs, I think, requires a special folder and you must put files into that to get version backups. I didn't like that cumbersomeness).


Depends on how much you value your data, and your time to deal with a loss, if you can.
 

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