Disk speed of my Macbook SSD is worse than most of my VPSs?

William

yea, an AIR, but as addition, not as replacement

MrAndroid

OS X's version of DD (BSD DD) works differently to GNU DD. You can install GNU DD by installing HomeBrew and using brew install core-utils.

You can then use GNU DD by putting g in front of dd. That way you'll get a fair test.

happel

You people really overappreciate your trim. On a desktop system (or laptop) the hdd/ssd is idle most of the time, during this idle time the garbage collection of the ssd cleans up most of the mess. Sure you'll lose a little bit of performance without trim, but it won't suck.

I'm using the ssd drive in my macbook as extra memory since it only has 2GB of ram (most of the time I have at least 2-3GB of swap active) without trim enabled. I have been doing this for a year and a half now and experienced no slowdown whatsoever.

JTR

@George_Fusioned said: Also, what kind of speed results do you get with "Blackmagic Disk Speed Test"? (you can get it from the App Store for free)

Here are mine (it's a 840 Pro though):

Do you have the 128GB? I have the 256GB and get far better results than that...

Kris

~74 Mb/s on a 2011 edition iMac, still chugging along with a 1GB SATA and 4GB of RAM. Yeehaw!

JonathanZhang

@shovenose said: It's a Mac :P that's the issue.

+1

SplitIce

Generally speaking larger SSDs achieve better performance as they have more chips that can be written to at any time (the limitation on this is the controller). Atleast from my experience with Windows laptops, Desktops and Servers.

If you arent getting 150MB/s+ there is something wrong with your SSD, firmware or operating system. Im surprised no one has mentioned it but have you checked the health status (SMART)?

Chan

@MrAndroid said: You can then use GNU DD by putting g in front of dd. That way you'll get a fair test.

chan@mbp ~ $ gdd if=/dev/zero of=test bs=64k count=16k conv=fdatasync 16384+0 records in 16384+0 records out 1073741824 bytes (1.1 GB) copied, 4.36624 s, 246 MB/s

Not too much of a difference but thanks for the advice anyway

George_Fusioned

@JTR said: Do you have the 128GB? I have the 256GB and get far better results than that...

Yeap it's the 128GB one. The 256GB would definitely perform better.

MrAndroid

@SplitIce said: Generally speaking larger SSDs achieve better performance as they have more chips that can be written to at any time (the limitation on this is the controller). Atleast from my experience with Windows laptops, Desktops and Servers.

I generally have this rule, although its not really accurate at all because your SSD speed depends on other factors too. If you have a 20GB SSD, you'll get around 20MB/s, a 40GB SSD around 40MB/s, a 256GB SSD around 256MB/s and a 500GB SSD around 500MB/s and so on.

heiska

@MrAndroid said: I generally have this rule, although its not really accurate at all because your SSD speed depends on other factors too. If you have a 20GB SSD, you'll get around 20MB/s, a 40GB SSD around 40MB/s, a 256GB SSD around 256MB/s and a 500GB SSD around 500MB/s and so on.

I can confirm that your rule isn't really accurate. 32GB Sandisk SSD:

dd if=/dev/zero of=test bs=64k count=16k
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 9.56928 s, 112 MB/s

MrAndroid

@heiska said: I can confirm that your rule isn't really accurate. 32GB Sandisk SSD:

Exactly.

kryps

Ubuntu 12.04 running in VMWare Player on Win7 on a Macbook Air 13" with 256GB SSD (Samsung)

xxx@ubuntu:~$ dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync
16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 2.78355 s, 386 MB/s

So something really seems to be fishy on your machine. I will retry on OSX when I next boot it.

Raymii

@George_Fusioned said: btw I assume this 120MB/sec result is from your Storage VPS, not an SSD VPS, correct?

Yep, storage VPS, not SSD one. Wasting SSD speed for a few nightly backups where the network is the bottleneck is not my thing...

@George_Fusioned said: Also, what kind of speed results do you get with "Blackmagic Disk Speed Test"? (you can get it from the App Store for free)

It has the 6 GPBS enabled. Black Magic gives me about 14 MB write and 20 MB read...

@William said: yea, an AIR, but as addition, not as replacement

Did you get all yer stuff back already?

@William said: Do also note if you use a HDD adapter kit for the CD/DVD drive that this port only has 3Gbit in hardware, a SSD there is not a good choice.

Plugs right in... Enabled TRIM but it doesn't seem to help much. I think I'll send it back as faulty...

@kryps said: So something really seems to be fishy on your machine. I will retry on OSX when I next boot it.

I think it's a faulty disk seeing all the other speeds...

---

The stupid thing is that with a regular HDD i got about 50mbps, even with Filevault enabled. This is on the SSD without filevault, when I enable that it won't even boot anymore...

heiska

@kryps said: Ubuntu 12.04 running in VMWare Player on Win7 on a Macbook

Well that's an interesting setup.