SSD and copy speed

[xerox]

I have an Asus vivo pc with dual sata bay :

I'm trying to copy disk image with dd :
dd if=/dev/sdb of=/home/test/myimage.img(sda) bs=128kb

Despite SSD are 500Mb/sec RW capable , transfer rate is 26MB/sec

Where is the bottleneck ? Bay itself, machine performances, cpu, ram, etc . ??

 

[Trenix25]

I have an Asus vivo pc with dual sata bay :

I'm trying to copy disk image with dd :
dd if=/dev/sdb of=/home/test/myimage.img(sda) bs=128kb

Despite SSD are 500Mb/sec RW capable , transfer rate is 26MB/sec

Where is the bottleneck ? Bay itself, machine performances, cpu, ram, etc . ??

I have found that increasing the block size to like 4M helps it work better, but your transfer rate looks more like mine. I'm using a USB3.x hard drive and matching port. Play with your block size and used buffered I/O. Don't use iflag=direct or oflag=direct as this is unbuffered I/O.

Signed,

Matthew Campbell

 

[xerox]

I used many times USB to SATA adapters, I thought throughput over USB was poor dued to that interface conversion, and sata to sata bus was faster, but it isn't true, the cause resides somewhere else....

 

[Brickwizard]

my guess would be the bay, if the drives are in parallel [both feeding into a single connection to the motherboard], this will reduce the speed if both are in use,
as it is the nominal speed of an SSD varies by make and format, the theoretical speed on a single SAT3 connection is 6gbs [assuming the connection is using a STA3 cable] or a SATA 2 connection of 3gbs, the actual speed can be as low as 4.5gbs and 2.4gbs respectively

 

[xerox]

Well.... with bs=4M it jumps to a nice 160Mb/s....
Thanks