Arch Linux

ben106

Member

From: Switzerland

Registered: 2009-04-25

Posts: 16

Can I get more out of my Corsair SSD ?

Hi,
I just bought a new computer and installed arch on it. I got two "hard disks" : one 500GB hard disk and one 64GB SSD. When I ran bonnie++, I'm not getting fabulous write results for the SSD :

64GB Corsair CMFSSD Extreme :

500GB WD 7'200rpm HDD :

hdparm -tT :

/dev/sda: (the 64GB SSD)
 Timing cached reads:   8228 MB in  2.00 seconds = 4115.22 MB/sec
 Timing buffered disk reads:  214 MB in  3.01 seconds =  70.99 MB/sec

/dev/sdb: (the 500GB HDD)
 Timing cached reads:   8186 MB in  2.00 seconds = 4094.63 MB/sec
 Timing buffered disk reads:  288 MB in  3.02 seconds =  95.39 MB/sec

fdisk -l :

Disque /dev/sdb: 500.1 Go, 500107862016 octets
255 têtes, 63 secteurs/piste, 60801 cylindres
Unités = cylindres de 16065 * 512 = 8225280 octets
Identifiant de disque : 0x69458e33

Périphérique Amorce  Début        Fin      Blocs     Id  Système
/dev/sdb1               1           4       32098+  83  Linux
/dev/sdb2               5        1000     8000370   83  Linux
/dev/sdb3   *        1001       11444    83886080    7  HPFS/NTFS
/dev/sdb4           11444       60801   396464672+   5  Etendue
/dev/sdb5           11444       41323   240003036   83  Linux
/dev/sdb6           41323       60801   156461573+   7  HPFS/NTFS

Disque /dev/sda: 64.0 Go, 64023257088 octets
224 têtes, 56 secteurs/piste, 9968 cylindres
Unités = cylindres de 12544 * 512 = 6422528 octets
Identifiant de disque : 0xaa02850f

Périphérique Amorce  Début        Fin      Blocs     Id  Système
/dev/sda1               1        1673    10493028   83  Linux
/dev/sda2            1674        9968    52026240   83  Linux

[benjamin@enceladus ~]$ uname -a
Linux enceladus 2.6.32-ARCH #1 SMP PREEMPT Thu Jan 7 22:28:29 CET 2010 x86_64 AMD Phenom(tm) II X4 965 Processor AuthenticAMD GNU/Linux

The partitions tested were formatted in standard ext4 (no special options). The SSD is using the deadline scheduler and is mounted relatime. The motherboard is an Asus M4A79XTD EVO with a SB750 SATA chipset. I choose AHCI mode for all SATA devices in the BIOS. 8GB of RAM are installed.

They tested my SSD on this website and got about 150 MB/s write speed and 200-250 MB/s read speed.

What I'm finding strange is that HDD and SSD have almost the same per char and block write speed, and stranger : that the result of hdparm -tT are worse for the SSD !

So my question is : how can I reach the 150 MB/s write speed ? Maybe some clues..? Or at least explain these results.. And I'm quite amazed by the results of my cheap HDD..! (I think I was stuck some years in the past...)

saharchie

Member

Registered: 2008-09-17

Posts: 20

Re: Can I get more out of my Corsair SSD ?

hopefully you have achieved SSD nirvana by now, but if not here are some thoughts I had ... unfortunately it is going to take a combination of tweaks and some trial-and-error to determine what actually works best in your computer.

-- Proper alignment is probably the most critical

-- block size when formatting -- there should be noticeable speed differences depending on chosen block size.

-- drive tuning -- it seems folks have gravitated to ext4 noatime , w/o journal ...

-- scheduler -- personally I use noop, but I mentally flipped a coin between it and deadline ... I have yet to try deadline.

In regards to testing ... all of those +++++ at the end of bonnie means that particular section of the test completed too fast to calculate .... I <3 bonnie, but I'm too impatient ... hdparm works fine for me 

hope that helps

Last edited by saharchie (2010-01-28 16:22:09)

ben106

Member

From: Switzerland

Registered: 2009-04-25

Posts: 16

Re: Can I get more out of my Corsair SSD ?

Thanks for all these thoughts

I read a bit more about alignment, and it seems that Corsair SSDs don't need alignment (found this on the Corsair's forum).. So I hope I didn't do wrong by trying to align it..!

Didn't think about block size when I formatted.. So now I have 4k blocks, the not-so-fastness might come from here ! I will study this a little bit more..

And here is a new bonnie++ result, the filesystem is mounted with barrier=0 :

So this helps a little bit.

I think the next step will be 64k blocks (needs some more googling) to have real improvements. Anyway, write speed is not so important finally (the wise man spoke..), but nice to have I'll give some news when I change the blocks size

Oh, and happy to know that these ++++ mean too fast