eSATA running very slow.

S

ScarsUnseen

Weaksauce
Joined
Jul 9, 2007
Messages
121
Can someone please explain to me why my eSATA hard drive is a lot slower than 3Gbits/second?

On my desktop, it's running at about 55MB/sec and on my laptop about 35MB/sec. On my laptop (Dell Inspiron 1318), I'm using eSATA with an ExpressCard/54 eSATA adapter.

Thanks!
 
I took the 250gb drive out of a Maxtor OneTouch 2.5" USB enclosure and put it into a Thermaltake eSATA enclosure. I was under the impression that the advertised 3Gbits/sec was the same as 384MB/sec.
 
lol @ 384MB/sec

Sry man... but no that won't ever happen. Well at least in this generation without raid and etc.
 
Well am I at least accurate in my conversion? :p

What is typically a realistic speed for eSATA then?
 
Pretty much roughly the same as regular SATA.

Unless that express SATA card is using some low chipset.
 
ScarsUnseen said:
Well am I at least accurate in my conversion? :p

What is typically a realistic speed for eSATA then?
Click to expand...

3 Giga bits = 3000 Mega bits..... 3000 / 8 (8 bits in a byte) = 375.... 375 MB/s

So you were close.

Also your speeds are normal, but I think they could be faster. Maybe it is because of the file size you are transferring, the way your HDD is connected, or the HDD in general. My WD1001FALS rarely drops below 90 MB/s and on average is around 100 MB/s.
 
ScarsUnseen said:
Well am I at least accurate in my conversion? :p

What is typically a realistic speed for eSATA then?
Click to expand...
3.0 gbps is the raw interface speed, but protocol overhead will eat some of that, you'd really only expect to get about 80% of that in real world situations. But that's only talking about the interface. The drive itself will never be able to pull data off the platters at that speed, or at least not for the foreseeable future.

Most consumer harddrives can only acheive 70-110MB/s average transfer. Some will burst transfer upto 150-200MB/s.

Google search of 250GB harddrive benchmarks:
http://www.tomshardware.com/reviews/sata-hard-drives-run-riot,709-9.html

55-60MB/s looks typical for that size and vintage of drive? For why it's slower when connected to the laptop? There are several conversions taking place, eSATA to ExpressCard interface, software drivers, low-power low performance design due to laptop's small thermal/power capability. Lots of potential reasons for why it's slower on the laptop, but it would all be guessing.
 
hhara said:
Also your speeds are normal, but I think they could be faster. Maybe it is because of the file size you are transferring, the way your HDD is connected, or the HDD in general. My WD1001FALS rarely drops below 90 MB/s and on average is around 100 MB/s.
Click to expand...
Your 1TB WD drive is a modern drive, with 3 x 333GB platters, so fairly dense platters (meaning a lot of bits travel across the read heads per second as the disc spins), large cache size and generally optimized for performance since it's a Black series I think.

The 250GB drive he has salvaged from an external enclosure, is generally a low cost solution, targeted for backup purposes and not speed. And probably has a pair of 125GB platters, very low density (not as many bits pass under the read heads per second), not to mention probably smaller cache size.
 
hhara said:
3 Giga bits = 3000 Mega bits..... 3000 / 8 (8 bits in a byte) = 375.... 375 MB/s

So you were close.

Also your speeds are normal, but I think they could be faster. Maybe it is because of the file size you are transferring, the way your HDD is connected, or the HDD in general. My WD1001FALS rarely drops below 90 MB/s and on average is around 100 MB/s.
Click to expand...
Close.

SATA1 = 1.5Gbit/s, due to protocol encoding overhead only about 1.2Gbit/s is going to be practical. 1200 / 8 = 150MB/s.

SATA2 doubles this to 300MB/s
and of course SATA3 will double this again to 600MB/s.

Again, to the OP, keep in mind this is only applicable to the interface, there are other bottlenecks.
 
Menelmarar said:
Close.

SATA1 = 1.5Gbit/s, due to protocol encoding overhead only about 1.2Gbit/s is going to be practical. 1200 / 8 = 150MB/s.

SATA2 doubles this to 300MB/s
and of course SATA3 will double this again to 600MB/s.

Again, to the OP, keep in mind this is only applicable to the interface, there are other bottlenecks.
Click to expand...

How did I know the correction police were going to show up...

I was going off of the advertised speed of SATA II, which is what she was asking... 3 Gb/s.

Watch me do what you just did....

SATA1 = 1.5Gbit/s, due to some other overhead you forgot about only 1.1Gbit/s is going to be practical. 1100 / 8 = 137.5MB/s

SATA2 doubles this 275 MB/s.

Thanks.
 
Last edited:
hhara said:
How did I know the correction police were going to show up...

I was going off of the advertised speed of SATA II, which is what she was asking... 3 Gb/s.

Watch me do what you just did....

SATA1 = 1.5Gbit/s, due to some other overhead you forgot about only 1.1Gbit/s is going to be practical. 1100 / 8 = 137.5MB/s

SATA2 doubles this 275 MB/s.

Thanks.
Click to expand...
Sorry, some people on these forums like learning new things.

The difference here is you pulled 1.1Gbit/s out of your ass, I pulled 1.2Gbit/s from the fact that that's what you have left over after encoding overhead, which I previously mentioned. You're obviously not familiar with such, soooo.

SATA, like many interfaces use 8b/10b encoding. It's an encoding method used in MANY data protocols to maintain a zero DC bias. DC can't pass through some circuits, e.g. transformers like used for Ethernet phys, and maybe other interfaces as well. DC has a tendency to drift over long distances, if it drifts to far then you can get wrong values for bits, 1 as a zero or vise versa. Sure, a 1meter eSATA cable doesn't seem very long, but when the signaling is very fast and the voltage levels very low, it factors in. There may be other issues with DC as well, it's been a long time since data comm class.

8bits of user data is encoded into 10bit chunks in a way that minimizes the chances for long series of 1's or 0's. This is what causes only 80% of bandwidth usable for the end-user.

1.5Gbit * 0.80 = 1.2Gbit / 8 = 150MB/s. You can do the same calculation direct for SATA2 or SATA3 e.g. 6Gbit * .8 = 4.8Gbit/s / 8 = 600MB/s. I only started at SATA1 before for the OP's benefit and since I figure that old 250GB drive may be a SATA1 drive. *shrug*.
 
Menelmarar said:
3.0 gbps is the raw interface speed, but protocol overhead will eat some of that, you'd really only expect to get about 80% of that in real world situations. But that's only talking about the interface. The drive itself will never be able to pull data off the platters at that speed, or at least not for the foreseeable future.

Most consumer harddrives can only acheive 70-110MB/s average transfer. Some will burst transfer upto 150-200MB/s.

Google search of 250GB harddrive benchmarks:
http://www.tomshardware.com/reviews/sata-hard-drives-run-riot,709-9.html

55-60MB/s looks typical for that size and vintage of drive? For why it's slower when connected to the laptop? There are several conversions taking place, eSATA to ExpressCard interface, software drivers, low-power low performance design due to laptop's small thermal/power capability. Lots of potential reasons for why it's slower on the laptop, but it would all be guessing.
Click to expand...
I linked a comparison of 3.5" desktop hard drives there. I just noticed that you said your 250GB Maxtor is a 2.5", that means mobile drive, which means focus on low power, which generally means lower performance.

I also just googled, and it's a 5400rpm drive, not even 7200rpm. So there is some more performance loss there.

Obviously this doesn't take into account the disparity between desktop and laptop, but I already addressed that guessing as far as the expresscard's esata implementation may be low-cost, low-power since it's targetted at the mobile market. Additionally it's hardware and drivers have to translate the data from eSATA to ExpressPort and relay that to Windows which may or may not involve some overhead.
 
Menelmarar said:
Your 1TB WD drive is a modern drive, with 3 x 333GB platters, so fairly dense platters (meaning a lot of bits travel across the read heads per second as the disc spins), large cache size and generally optimized for performance since it's a Black series I think.

The 250GB drive he has salvaged from an external enclosure, is generally a low cost solution, targeted for backup purposes and not speed. And probably has a pair of 125GB platters, very low density (not as many bits pass under the read heads per second), not to mention probably smaller cache size.
Click to expand...

IIRC, the Black 1TB also has a 2nd processor.

He said it was a 2.5" drive...

ScarsUnseen said:
I took the 250gb drive out of a Maxtor OneTouch 2.5" USB enclosure and put it into a Thermaltake eSATA enclosure. I was under the impression that the advertised 3Gbits/sec was the same as 384MB/sec.
Click to expand...

ScarsUnseen said:
... On my desktop, it's running at about 55MB/sec and on my laptop about 35MB/sec. On my laptop (Dell Inspiron 1318), I'm using eSATA with an ExpressCard/54 eSATA adapter.
Click to expand...

55MB/s using what tool to measure this? HD Tach? HD Tune? Crystal Drive Mark? ATTO?

55MB/s for a 2.5" drive is actually a nice speed. Though, its not as old as its 3.5" brothers, which also run around the same speed, 55MB/s.

At 35MB/s, it sounds like the express card is running in USB mode instead of PCI-Express mode, if thats even possible? iunno...

Here's a nice thread to check out: http://www.hardforum.com/showthread.php?t=1284410
 
Menelmarar said:
1.5Gbit * 0.80 = 1.2Gbit / 8 = 150MB/s. You can do the same calculation direct for SATA2 or SATA3 e.g. 6Gbit * .8 = 4.8Gbit/s / 8 = 600MB/s. I only started at SATA1 before for the OP's benefit and since I figure that old 250GB drive may be a SATA1 drive. *shrug*.
Click to expand...
I should also add, that I'm still rambling in base10. If you're watching the transfer window in Vista/7, moving files over, it's going to be reporting what ISO now calls MiB and calling them by the old and confusing nomenclature from JEDEC, MB. So you'd have to divide by 1024^2. 1024 B in a KiB, and 1024KiB in a MiB.

Skipping straight to SATA2, 3Gbit/s
3Gbit/s * 0.80 (encoding) = 2.4Gbit / 8 (bits to bytes) = 300MB/s / 1024^2 (MB to MiB) = 286 MB/s.

Fun w/ numbers =) and really completely irrelevant to your problem.

As mentioned, gotta be the expressport card. Enginurd's idea about it operating in USB mode sounds interesting, even probable. But I have no experience with them.
 
You guys gonna circle-jerk each other also to see who's better?

Thanks for the responses, but holy crap, chill out. This is how wars are started.
 
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