SATA performance with SSDs?

The magic smoke.

Moderators: phlip, Moderators General, Prelates

commodorejohn
Posts: 849
Joined: Thu Dec 10, 2009 6:21 pm UTC
Location: Placerville, CA
Contact:

SATA performance with SSDs?

Postby commodorejohn » Mon Oct 31, 2016 9:12 pm UTC

So I'm looking at getting a new(-ish) laptop, and I thought I might finally try using an SSD, now that they're getting to a point where a reasonably large drive can be had fairly cheap. I picked up a 240GB SATA-III SSD on sale, so I've got that down, but I'm still trying to decide between a Thinkpad T430 (a nice machine, I helped my mother pick one out recently) and a Thinkpad X201 (I like smaller laptops, and it sounds like the battery life is significantly better.) In most respects that are relevant for my purposes, the two are pretty comparable, but one key difference is that the X201 only supports SATA-II.

What I'm not clear on is whether this makes a meaningful difference in actual disk performance, when the SSD I bought only claims ~530 MB/s maximum read rate. Granted, that's still handily more than the maximum throughput for SATA-II, but then I assume that the quoted figure is a "lies, damn lies, and benchmarks" figure anyway. Any thoughts on whether this would lead to a significant loss in disk performance in practice? And if I'm basically comfortable with spinning-rust data rates anyway, is it likely to be a big issue?
"'Legacy code' often differs from its suggested alternative by actually working and scaling."
- Bjarne Stroustrup
www.commodorejohn.com - in case you were wondering, which you probably weren't.

speising
Posts: 1899
Joined: Mon Sep 03, 2012 4:54 pm UTC
Location: wien

Re: SATA performance with SSDs?

Postby speising » Mon Oct 31, 2016 9:36 pm UTC

One thing i can predict confidently: after you've tried an SSD, you'll never be comfortable with a clunky spinning platter anymore.

User avatar
Weeks
Hey Baby, wanna make a fortnight?
Posts: 1761
Joined: Sat Aug 23, 2008 12:41 am UTC
Location: Panama

Re: SATA performance with SSDs?

Postby Weeks » Mon Oct 31, 2016 10:33 pm UTC

speising wrote:One thing i can predict confidently: after you've tried an SSD, you'll never be comfortable with a clunky spinning platter anymore.
As an avid, joyful SSD user, I can attest to this.
Am I gregnant
suffer-cait wrote:One day I'm gun a go visit weeks and discover they're just a computer in a trashcan at an ice cream shop.
rath358 wrote:manually adding a long list of swear words to my dictionary worked.

ThemePark
Posts: 450
Joined: Fri Jun 27, 2008 5:42 pm UTC
Location: Århus, Denmark

Re: SATA performance with SSDs?

Postby ThemePark » Mon Oct 31, 2016 11:08 pm UTC

I'm assuming the T430 does support SATA III, in which case I'd probably pick that. Your SSD won't be utilized fully if you connect it to SATA II because of its maximum throughput of 300 MB/s. But since you already have a computer, perhaps you could test your SSD with that first. And run a speed test on both your current harddisk and the SSD so you can get a feel of how much faster it would be with SATA II vs SATA III. Does your current computer use SATA II or SATA III?
I have traveled from 1979 to be a member of the unofficial board Council of Elders. Phear M3

KnightExemplar
Posts: 5201
Joined: Sun Dec 26, 2010 1:58 pm UTC

Re: SATA performance with SSDs?

Postby KnightExemplar » Tue Nov 01, 2016 1:24 pm UTC

commodorejohn wrote:So I'm looking at getting a new(-ish) laptop, and I thought I might finally try using an SSD, now that they're getting to a point where a reasonably large drive can be had fairly cheap. I picked up a 240GB SATA-III SSD on sale, so I've got that down, but I'm still trying to decide between a Thinkpad T430 (a nice machine, I helped my mother pick one out recently) and a Thinkpad X201 (I like smaller laptops, and it sounds like the battery life is significantly better.) In most respects that are relevant for my purposes, the two are pretty comparable, but one key difference is that the X201 only supports SATA-II.

What I'm not clear on is whether this makes a meaningful difference in actual disk performance, when the SSD I bought only claims ~530 MB/s maximum read rate. Granted, that's still handily more than the maximum throughput for SATA-II, but then I assume that the quoted figure is a "lies, damn lies, and benchmarks" figure anyway. Any thoughts on whether this would lead to a significant loss in disk performance in practice? And if I'm basically comfortable with spinning-rust data rates anyway, is it likely to be a big issue?


The primary benefit of SSDs is not bandwidth (although SSDs do have better bandwidth numbers), its latency.

Consider how Firefox works. When you double-click on Firefox... here's what happens:

1. The Hard Drive needs to spin to the shortcut location (to find the .exe file)
2. The Hard Drive needs to spin to the .DLL location (.EXE files have associated .DLL files to help them load). This is on another location on the hard drive
3. The Hard Drive needs to spin to find your "last opened" files
4. Hard drive needs to look for your bookmarks

Etc. etc. etc.

Each time your computer looks for another file, it needs to move the arm on the hard drive. A Hard Drive is a physical device, and it takes roughly 5-milliseconds each time to open up a new file. The best hard drives have roughly 150 IOPS. (That is: Input / Output operations Per Second).

Image

-----------

Solid State drives also have a limitation on IOPS, although it has to do with voltages accessing databanks. Cheap SSDs have roughly 10,000 IOPS, or a 66x increase over hard drives. Expensive SSDs have 200,000+ IOPS.

So while SSDs are "only" 3x faster with bandwidth (500MB/s or SSDs instead of 150MB/s for Hard Drives), in practice... most operations are limited by IOPS, which SSDs are dozens or hundreds of times faster. The Mushkin Reactor 1TB (only $240) is rated at 71,000 IOPS... that is, it can "visit" 71,000 different files per second.

While expensive SSDs (like the Intel 750) have 430,000 IOPS.

-------

So best case vs best case Hard Drives vs SSDs you get something like 4x better performance out of an SSD.

Worst case vs worst case, you get something like 700x better performance out of SSDs. Hard Drives just have a horrible worst-case scenario of ~100 IOPS.
First Strike +1/+1 and Indestructible.

commodorejohn
Posts: 849
Joined: Thu Dec 10, 2009 6:21 pm UTC
Location: Placerville, CA
Contact:

Re: SATA performance with SSDs?

Postby commodorejohn » Tue Nov 01, 2016 2:09 pm UTC

Yeah, that's what I was hearing out of another forum.
"'Legacy code' often differs from its suggested alternative by actually working and scaling."
- Bjarne Stroustrup
www.commodorejohn.com - in case you were wondering, which you probably weren't.


Return to “Hardware”

Who is online

Users browsing this forum: No registered users and 1 guest