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External HDD vs External HDD Enclosures? Help me please.

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April 11, 2011 7:38:23 AM

Right now I have a desktop pc with two WD internal HDDs, one is 1 TB and the other is 2 TB.

Soon I'll get a Dell XPS L502X notebook and I'll install in it a 240 GB OCZ Vertex 3 SSD which will be my only internal drive.

I'm planning to get rid of the desktop pc and make the notebook my only computer. But I'll need lots more space.

So I guess I have two options: Getting external hard drive(s) or getting external hdd enclosures for the hdds currently in my desktop pc.

My HDDs are both sata drives and support 3 GB/s. Links to each hdd's specs:

WD1001FALS (1TB, 32 mb cache)
WD20EARS (2 TB, 64 mb cache)

The notebook has two USB 3.0 ports (as well as an esata port) and supports 6gb/s as far as I know, but I maybe wrong about that.

1 . With what kind of setup can I get the best transfer and data access speeds?

2. Would placing these hdds in external enclosures that support usb 3.0 be as efficient as getting external hdds? I could purchase new HDDs (with 6 gb/s support) also, if that's what I need to do to achieve the best possible speeds...

3. I'm also open to recommendations for external hdd enclosure brand/models.

4. Also, I read that USB 3.0 is ten times faster than USB 2.0, but it doesn't get more than three or four times the speed of usb 2.0 (around 100 mb/s), right? Why is that?

Thanks in advance for your replies.

Regards.


a b G Storage
April 11, 2011 9:34:10 AM

The biggest bottleneck, if you're going to be using USB 3.0 or eSATA is the hard disk itself. So no matter which one you use, you'll probably get the same transfer rates. So slap those HDs onto a USB 3.0 enclosure. Even if the drivers were SATA 6Gbps ones, it's still the platters that slow the whole thing down.
April 11, 2011 12:19:09 PM

gracefully said:
The biggest bottleneck, if you're going to be using USB 3.0 or eSATA is the hard disk itself. So no matter which one you use, you'll probably get the same transfer rates. So slap those HDs onto a USB 3.0 enclosure. Even if the drivers were SATA 6Gbps ones, it's still the platters that slow the whole thing down.


Thanks for the reply. Since SSDs are still very expensive I have no choice but use HDDs unfortunately.

Still, even if it's going to be slow no matter what I do, I need to figure out which option is the faster/better...
Related resources
a b G Storage
April 11, 2011 1:55:36 PM

Going USB is better, since more devices have USB in them. USB 3.0 can work at USB 2.0 ports, although you'll go no faster than 30MB/s if you do so.

You don't really have to saturate the USB 3.0 bus. It's the same with USB2.0 and flash disks. I'm just saying that whether you choose USB or eSATA makes little difference in terms of performance, because the bottleneck is the HDD. But I suggest you go USB for easy compatibility with older devices.
April 11, 2011 2:10:16 PM

Thanks for the reply.

Going USB or not is not the question, though. HDD enclosure or external HDD? That's the question. Both setups will use USB 3.0. Another question is whether purchasing 6gb/s hdds would earn me more speed compared to the 3 gb/s hdds that I currently have?
a c 415 G Storage
April 11, 2011 4:48:11 PM

meurslys0 said:
Going USB or not is not the question, though. HDD enclosure or external HDD?
I'm not exactly sure what you mean here. You can't just buy a bare drive and no enclosure and use it with the computer, you need something to plug the drive into.

Are you asking about the difference between getting a full enclosure and getting a hard drive dock such as this?




I use this dock and find that it works just fine, as long as I'm careful to insert the drive solidly onto the SATA connector at the bottom. I prefer this to external enclosures because I have several external bare HDDs I use and I only need the one dock to use them all instead of separate enclosures for each drive.
a c 289 G Storage
April 11, 2011 5:29:21 PM

If you wanna fly, you could buy one of these http://www.newegg.com/Product/Product.aspx?Item=N82E168... and connect at eSata speeds. But USB 3.0 has similar specs, and is probably easier to interconnect with other things.

Since your notebook has native USB 3.0 ports, just buy the dock sminlal suggested (if it has USB 3.0) and be prepared for extreme transfer speeds. Just remember that USB 3.0 requires a different cable from USB 2.0 to run at full speed. If you use a USB 2 cable, you get USB 2 speeds.
a c 415 G Storage
April 11, 2011 7:54:59 PM

WyomingKnott said:
If you wanna fly, you could buy one of these http://www.newegg.com/Product/Product.aspx?Item=N82E168... and connect at eSata speeds.
I don't think that's going to be a good solution on it's own because it won't provide power to the external drive - you'll still need some sort of power adapter to plug into the wall - perhaps an enclosure with an external eSATA connector? But in that case you might as well just go for a USB enclosure and not bother with the extra adapter...

The drive dock I mentioned above does come with a power brick that plugs into a wall outlet and it provides power to the drive via the standard rear connector.
a c 289 G Storage
April 11, 2011 8:01:50 PM

sminlal

Isn't USB 3.0 specced faster than SATA II anyway? So my suggestion would be absolutely useless.
a c 415 G Storage
April 11, 2011 10:54:42 PM

WyomingKnott said:
Isn't USB 3.0 specced faster than SATA II anyway?
Yeah, although hard drives can't reach the speeds of either so it's a bit of a moot point.
a b G Storage
April 12, 2011 12:58:11 AM

...which was what I was saying from the beginning. :) 

I think the biggest consideration we have to make is interoperability and compatibility. Right now, there are many many more USB ports than eSATA ports. A USB 3.0 device would have more sockets to plug into, even if it will drop to USB 2.0 speeds.

Now, as for the question of *new* external HDD vs. enclosure/docks, do you plan to use those HDDs in other computers? If not, they'll go to waste, so might as well get an enclosure or dock for them, preferably USB ones.
April 12, 2011 2:26:55 AM

Thanks for all the replies.

I have to stick to HDDs for external storage right now, because I cannot afford 3+ GB SSDs. So I have to figure out the fastest possible setup I could have with these naturally-slow HDDs...

I'm considering getting this (or a similar item). Is there a faster option?

a b G Storage
April 12, 2011 2:37:02 AM

That's actually pretty nice. Since you have 3.5" HDDs anyway, you'll need them to be externally powered. That'll house both of them, as well as giving you two connectivity options. If you find that you need more space in the future, then you can fill up the two other bays.
a b G Storage
April 12, 2011 4:12:32 AM

Get an external enclosure that raid0, the one you want is not. Raid0 and you get the speed and huge space you want.
a b G Storage
April 12, 2011 6:46:59 AM

^
RAID0 is dangerous for file storage, as it provides no redundancy. If one drive in a RAID0 array fails, the whole thing is toast.

Besides, a 1TB and 2TB drive still gives 3TB of space, whether or not you put them in RAID. Since you won't be booting of the drives anyway, you can do with 100 MB/s sequential access.
a b G Storage
April 12, 2011 6:52:45 AM

Ok, but a lot of the raid0 enclosure also have raid5, so meurslys0 can do a raid 5 if he needs more redundancy. I mean if he is not going to use raid, then all of the SSD's speed advantage will be lost when he transfer large files from between laptop and external storage.
a b G Storage
April 12, 2011 7:09:09 AM

~100 MB/s doesn't seem slow to me. That's 10 GB in a minute and a half. For purposes of backup and file storage, you don't need a blazing fast SSD in my opinion.

With only 2 drives, RAID5 doesn't make sense. On top of that, the two drives don't have the same capacity, so either you lose the extra 1 TB, or configure the 1 TB as a member of RAID and the remaining 1 TB as normal space (is that even possible? I think I saw it somewhere). Besides, nothing's wrong with JBOD.
a b G Storage
April 12, 2011 7:15:13 AM

No, the 2T drive wont get up to 100MB/s. I have that drive myself. Those green drive are slow and only fast for transfer of a few gig because of the larger cache. For anything larger, they only go up to about 75 if drive is empty and 60 if the drive is full.
April 12, 2011 7:41:55 AM

gracefully said:
~100 MB/s doesn't seem slow to me. That's 10 GB in a minute and a half. For purposes of backup and file storage, you don't need a blazing fast SSD in my opinion.

With only 2 drives, RAID5 doesn't make sense. On top of that, the two drives don't have the same capacity, so either you lose the extra 1 TB, or configure the 1 TB as a member of RAID and the remaining 1 TB as normal space (is that even possible? I think I saw it somewhere). Besides, nothing's wrong with JBOD.


So how much performance difference are we talking about between RAID 0 and JBOD? I wouldn't commit suicide if I lost all the data on my hdds with RAID 0 as they will only be used to store music, video and software... Plus I could get a 2 TB HDD to use in RAID in place of the 1 TB one if needed. So how fast would be RAID 0 in file transfers and access times in mb/s?
a b G Storage
April 12, 2011 7:49:56 AM

In raid0 you get about n times the performance and n is number of disk. So, 2 disk about twice the speed, 3 disk about 3 times, etc. Until you saturate the sata or usb 3.0 interface. In raid,5 you get n-1 times the performance and you need minimum of 3 disk. So, 3 disk gives you 2x speed, 4 disk=3x speed, etc. Also, until you saturate your interface. I suspect a 2 disk raid0 of the 2T drive is about 120-140MB/s. Without raid, you get only the original speed.
a b G Storage
April 12, 2011 9:06:34 AM

Pyree said:
No, the 2T drive wont get up to 100MB/s. I have that drive myself. Those green drive are slow and only fast for transfer of a few gig because of the larger cache. For anything larger, they only go up to about 75 if drive is empty and 60 if the drive is full.


So to transfer a 10 GB file, you'd need 2 minutes instead of 1.5. In any case, that's not what I'm emphasizing. The main point of my argument is that RAID0 doubles the chance of failure versus simply having them as two disks. Let's say you have a 3 hard disk RAID0 setup. If even one of them fails, you'll lose everything. If you go RAID5, you need a good controller that can handle the parity calculation fast enough to saturate the drives themselves. Have you seen how dismally software RAID5 performed in a Core i5 system when it came to writes? It was writing at 15 MB/s. RAID5 is good, I'll give you that, since it only takes the capacity of one drive out of at least three to ensure that your data is protected from one drive failure.

meurslys0 said:
So how much performance difference are we talking about between RAID 0 and JBOD? I wouldn't commit suicide if I lost all the data on my hdds with RAID 0 as they will only be used to store music, video and software... Plus I could get a 2 TB HDD to use in RAID in place of the 1 TB one if needed. So how fast would be RAID 0 in file transfers and access times in mb/s?


What the other guy said, just read the stuff I wrote above this.

In my opinion, if you're going to go RAID for your data, either go RAID1 or RAID5. RAID0 is not worth the risk you're going to put yourself into, since it provides no redundancy. You'll only store music, video, and software (installers, I presume?), right? The only time you'll really feel the relative "slowness" of the drive is the first time you transfer files to it. If you'll transfer 1 TB of files in one go at 75 MB/s, it'll take around 4 hours. But after that, you're only going to access it. Even if you connect it via USB 2.0, you'll still be able to watch HD video, listen to your music, and access your software without noticeable slowness. It's up to you if you want to give RAID a try, but I suggest you go RAID5/RAID1, or no RAID at all.
April 12, 2011 2:00:48 PM

gracefully said:
So to transfer a 10 GB file, you'd need 2 minutes instead of 1.5. In any case, that's not what I'm emphasizing. The main point of my argument is that RAID0 doubles the chance of failure versus simply having them as two disks. Let's say you have a 3 hard disk RAID0 setup. If even one of them fails, you'll lose everything. If you go RAID5, you need a good controller that can handle the parity calculation fast enough to saturate the drives themselves. Have you seen how dismally software RAID5 performed in a Core i5 system when it came to writes? It was writing at 15 MB/s. RAID5 is good, I'll give you that, since it only takes the capacity of one drive out of at least three to ensure that your data is protected from one drive failure.



What the other guy said, just read the stuff I wrote above this.

In my opinion, if you're going to go RAID for your data, either go RAID1 or RAID5. RAID0 is not worth the risk you're going to put yourself into, since it provides no redundancy. You'll only store music, video, and software (installers, I presume?), right? The only time you'll really feel the relative "slowness" of the drive is the first time you transfer files to it. If you'll transfer 1 TB of files in one go at 75 MB/s, it'll take around 4 hours. But after that, you're only going to access it. Even if you connect it via USB 2.0, you'll still be able to watch HD video, listen to your music, and access your software without noticeable slowness. It's up to you if you want to give RAID a try, but I suggest you go RAID5/RAID1, or no RAID at all.


Thanks for all the help friends!

Is it possible to have 2 hdds in RAID 0 mode and have 1 or two other hdds as independent hdds in a single enclosure like this one or this one?


a b G Storage
April 12, 2011 3:13:04 PM

Yes, I'm pretty sure you don't have to use all the drives in the enclosure to build an array. You can probably have 2 in RAID0 and the rest as independent HDDs. Preferably, the drives you will put in RAID should be identical to maximize performance, although nothing's wrong with non-homogeneous RAID.

If you want a bit of redundancy, run RAID1 or RAID5 instead. RAID1 mirrors everything, so (if you have 2 identical drives), capacity is halved, but you are fully protected against a drive failure. If you have 4 drives in RAID1, you are protected from THREE drive failures (basically you're safe until the last drive), although as you can see, that's very inefficient.

RAID5 is best for 3 to 5 drives. You'll have to sacrifice an entire drive, but you are protected from a single drive failure. It doesn't matter which drive, since the data of any drive can be calculated using the data from the other drives. If ever a drive fails, you can "rebuild" the RAID5 array by putting in a new drive and letting the array "fill in" the missing data that should be in that drive.

I understand that the last paragraph isn't really necessary, but it might interest you to see what options you have for data protection.
a c 415 G Storage
April 12, 2011 10:11:59 PM

Pyree said:
No, the 2T drive wont get up to 100MB/s. ... they only go up to about 75 if drive is empty and 60 if the drive is full.
Are you talking about the WD20EARS? The transfer rates on the two that I use range from about 60MByte/sec up to 105MByte/sec depending on whether you're accessing the outer- or innermost tracks.


Regarding RAID arrays - you're going to need to back up the data on the RAID arrays anyway, since even RAID redundancy doesn't protect you from risks such as dropping the drive enclosure, having it stolen, corruption of the file system, etc. etc. The OP should worry about backup first and only consider RAID once that's been dealt with.
April 13, 2011 6:32:25 AM

gracefully said:
Yes, I'm pretty sure you don't have to use all the drives in the enclosure to build an array. You can probably have 2 in RAID0 and the rest as independent HDDs. Preferably, the drives you will put in RAID should be identical to maximize performance, although nothing's wrong with non-homogeneous RAID.


sminlal said:

Regarding RAID arrays - you're going to need to back up the data on the RAID arrays anyway, since even RAID redundancy doesn't protect you from risks such as dropping the drive enclosure, having it stolen, corruption of the file system, etc. etc. The OP should worry about backup first and only consider RAID once that's been dealt with.


Thanks for all the help friends.

I gave it a thought and I now think that I may not use the RAID function at all. Having many independent hdds in one enclosure with the ease of connecting them to my notebook via a single usb 3.0 cable with 100 mb/s transfer speed is good enough for me. In the future I may consider RAIDing them again.

For now I want to know for sure that the items listed below all

1- Let me have my hdds independent from each other (no raid)
2- Let me add or subtract hdds in the future without affecting other hdds
3- (Preferably) Turn on and shutdown with the notebook

Item 1

Item 2

Item 3

Item 4


4 - Which of these items would you recommend me?

5- For Item 1 and 3 the drive support is specified as "SATA I & SATS II" , for item 2 it is "SATA 150 & 300" and item 4 drive support seems to be plainly "SATA". Do I need to take these into consideration also?

So many questions I know. Thanks for bearing with me.




April 13, 2011 6:36:00 AM

Somehow I am not allowed to edit the message above...

EDIT:

5- For Item 1 and 3 the drive support is specified as "SATA I & SATA II" , for item 2 it is "SATA 150 & 300" and item 4 drive support seems to be plainly "SATA". Do I need to take these into consideration also?
April 13, 2011 7:17:23 AM

I just found another one on Ebay.

This one supprts up to 12 TB on 4 bays. I have two questions regarding this model:

1. In the specifications section it says:

"Bundled SATA 6.0Gbps PCIe 2.0 x1 controller card, support PCIe 2.0 with over 200MB/s performance."

Is this PCIe card compatible with Dell XPS L502X notebook? And what is its function?

2. In this site under the title "Online Raid Migration & Expansion" it is stated that...

"Utilizing dedicated high performance processor and advanced RAID design, TowerRAID Plus Series is capable of real-time RAID mode alteration, and hard drive capacity expansion without the need to erase existing data minimizing down time. This is also no need to move existing data to a temporary location. All changes are performed in the background without interrupting data availabilty."

What is described above applies to the model I have linked to right?
April 13, 2011 7:33:04 AM

(Continuing from above) This could mean I could use RAID after all and expand the set without having to erase all data and re-establish raid - which was the thing that drew me away from the idea of raid in the first place...
a b G Storage
April 13, 2011 12:47:19 PM

I'm not sure about the real-time RAID alteration thing. You can't simply break up a RAID0 or RAID5 array. You can't add a drive to a RAID0 array once it's been created either (I think). Lastly, to the best of my knowledge, creating an array requires the participating drives to be formatted. I think it's best to have everything set up before creating an array.

The PCIe controller card is for desktop only. It hooks up to a PCIe x1 slot. Since you'll be most likely to use USB 3.0 on your laptop anyway, you can keep that in a box or sell it. If your laptop has eSATA, then you won't need any peripheral at all.

Personally, I haven't experienced setting up or using a RAID array at all since I don't find the need for it, so I'm basing everything on speculation. Someone with experience will be able to tell you what it's like.

!