Monday, May 23

Geek

Apart From That, Mrs. Lincoln...

This shows just what a modern PC is capable of:


avg-cpu: %user %nice %sys %iowait %idle
0.42 0.00 60.42 39.16 0.00


Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sda 1080.00 69093.05 2.53 328192 12
sdb 1090.53 69793.68 0.00 331520 0
sdc 1110.32 71060.21 0.00 337536 0
sdd 1099.37 70359.58 0.00 334208 0
sde 661.89 42361.26 0.00 201216 0
sdf 647.58 41458.53 0.00 196928 0
sdg 277.68 17771.79 0.00 84416 0
sdh 279.16 17866.11 0.00 84864 0

Thats 400MB/sec of I/O, limited by the PCI connection to the second SATA controller. I have two PCI Express x1 slots, each of which can provide double that bandwidth, assuming I could find a cheap PCI Express SATA card (hah!) which would push my bandwidth up to 500MB/sec, which is as fast as the disks can go.

This isn't a fancy server motherboard either, just an ordinary desktop one. Albeit a nice desktop board.

This is my old system:


avg-cpu: %user %nice %sys %iowait %idle
0.40 0.00 43.40 56.00 0.20


Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
hdc 666.60 42611.20 8.00 213056 40
hdd 673.40 43046.40 8.00 215232 40
hde 445.00 28480.00 0.00 142400 0
hdf 445.00 28480.00 0.00 142400 0
hdg 503.60 32243.20 0.00 161216 0
hdh 503.80 32230.40 0.00 161152 0

Which isn't bad - about 200MB/s - but not in the same class. Here the fault is partly PCI, partly IDE, partly the previous generation disk drives.

My old 120GB IDE drives get around 45MB/s maximum transfer rate. The newer 200GB SATA drives reach 55MB/s, and the brand new 250GB drives can reach 70MB/s.

One interesting thing: The next major advance in hard disk technology is perpendicular recording, where the magnetic domains that hold the data are oriented vertically into the disk rather than longitudinally along the track. If you think of current bits like dominoes lying flat, perpendicular recording makes them stand on end, allowing them to be packed much closer together, up to ten times.

Most previous advances have come by making the overall area of the domains smaller, by making them shorter and packing the tracks closer together. Since the rotational speed of disk drives has increased only slowly, this meant that as the number of tracks increased, the time taken to read an entire disk also increased, climbing from minutes to an hour or more.

Perpendicular recording will increase transfer rates in direct proportion to the size of the disk, avoiding this problem. However, if we do achieve a ten-fold increase in capacity, transfer rates will far exceed even SATA-II's 300MB/s per channel.

Well, darn.

Posted by: Pixy Misa at 01:20 AM | Comments (1) | Add Comment | Trackbacks (Suck)
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Posted by: ya pidoras at Wednesday, July 26 2006 04:18 AM (nRwgX)

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