[SATLUG] Benchmarking SSD Drives

David Kowis dkowis at shlrm.org
Tue Jan 31 21:55:54 CST 2012


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On 01/31/2012 04:40 PM, Bruce Dubbs wrote:
> I had a friend loan me an SSD device.  It is a card that mounts in 
> a PCI slot, but does not actually use the PCI connector.  The card 
> has a power connector and a SATA connector.
> 
> I'm trying to check it out.  It formatted fine (ext3 for now).
> 
> The card inserted into this device is a SanDisk SDCFH-008G.
> 
> Testing with hdparm:
> 
> hdparm -tT /dev/sdc
> 
> /dev/sdc: Timing cached reads:   14842 MB in  2.00 seconds = 
> 7430.48 MB/sec Timing buffered disk reads: 130 MB in  3.01 seconds 
> =  43.16 MB/sec
> 
> Timing my conventional drives:
> 
> hdparm -tT /dev/sda
> 
> /dev/sda: Timing cached reads:   14796 MB in  2.00 seconds = 
> 7407.85 MB/sec Timing buffered disk reads: 332 MB in  3.01 seconds 
> = 110.32 MB/sec
> 
> hdparm -tT /dev/sdb
> 
> /dev/sdb: Timing cached reads:   14984 MB in  2.00 seconds = 
> 7502.19 MB/sec Timing buffered disk reads: 330 MB in  3.01 seconds 
> = 109.70 MB/sec
> 
> So the cached reads are all basically the same.  This seems 
> reasonable since the system is actually bypassing the drive.
> 
> On the other hand, the SSD device says 30GB on the card, but the 
> buffered reads are only half that of the standard drives.
> 
> OTOH, a copy of a 541M file gives:
> 
> time cp Fedora-16-x86_64-Live-LXDE.iso xxx
> 
> On SSD SanDisk SDCFH-008G : real 0m5.386s  (100 MB/s) On Seagate 
> ST3750330AS    : real 0m3.257s  (166 MB/s)
> 
> Does anyone have any experience with these.  It's mysterious to me 
> that the SSD is only about half the speed of the standard SATA 
> drives.  Are there some configuration items that need to be set? 
> BIOS?  Kernel?

That's not an SSD, that's a Compact Flash card. Well, technically it
is a solid state drive, but it's not the generally accepted thing
someone comes up with when they hear SSD.

Your product is listed here as an 8GB CF card at about 30MB/s
http://www.sandisk.com/products/dslr/sandisk-ultra-compact-flash

They're only rated for about 30MB/s so your numbers might be right

I'd say it's your Compact Flash card, it's just not that fast.

David
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