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Survey of buying new external harddisk supported by linux.

Hi guys,

As for the moment, i am using a seagate 160GB 7200 SATA hard drive with an external casing(unbranded). It is connected through USB2 interface and when i test the speed of the hard drive using hdparm, the output was :-

Code:

user1@madjack:/media# hdparm -Tt /dev/sdb



/dev/sdb:

 Timing cached reads:  1988 MB in  2.00 seconds = 994.80 MB/sec

 Timing buffered disk reads:  94 MB in  3.02 seconds =  31.15 MB/sec

user1@madjack:/media#

Does 31MB/sec considered as normal speed? Since it wasnt on SATA interface, i could not hope the speed will be about 55MB/sec. But now im thinking of getting a new hard drive. Would it be better if i go for more ideal external hard drive such as Seagete 3.5" FreeAgent hard drives or Western Digital's myBook series? im looking for performance, not look or compact size. Or should i just get another 3.5" 7200rpm harddrive, which is more cheaper than Seagate FreeAgent and others?

If you guys had experiences using these hard drives on linux, would you mind to share with me? Thanks!!

Your bottleneck is not the drive, but the USB2 interface. See http://www.everythingusb.com/usb2/faq.htm, particularly question number 4.

hmm..so this means that if i get a portable 2.5" 5400rpm harddisk will also makes no different with 3.5" 7200 rpm ones?

I think so, although I've no way of directly comparing speeds on my a single system.

However, my 2.5" USB2 120GB external drive (presumably 5400 RPM) achieves an average speed of 31.2MB/s, which is comparable to your 160GB 7200 SATA drive, although I did my benchmark here at work on a Windows machine. I doubt it'd be very different were I to do it at home on my Linux box.

Quote:

Originally Posted by pwc101 (Post 2937679)

i did tried to do the benchmark on windows using hdtach and the speed is more or less the same. but could you let me know your speed result on your linux box if you happen to have time to test it? i would really like to make a smart choice before getting any hard drive. thanks for your time!

I'll see if I can remember, but I'm going to be pretty busy this weekend, so might not get around to it.

While I was at it, I ran hdtach on a firewire400 250GB LaCie hard drive (presumably 7200 RPM), and got an average transfer speed of 39.2MB/s. So, if you want faster transfer, consider firewire, if you have it - an firewire800 is twice the speed of firewire400, so things would really move over that bus :) Also, firewire is entirely hardware, so there's no virtually CPU utilisation, unlike USB which used about 4% of my CPU during the tests on the 2.5" external disk.

Something to consider :)

yeah..im using dell inspiron 6400 and it has firewire port. how about the linux support of firewire800 or firewire400? is it reliable? oh..by the way, im a slackware fan too. ;)

Well, I can't say I've ever tried firewire, but as I understand it, it'd just be a case of having the appropriate kernel modules loaded (almost certain) and then mounting it (udev or fstab are your friends here). I don't think it'd be much more complicated than USB to be honest.

Ok, here's the results for the same 2.5" external disk, but from Slackware 12.0:

Code:

pwc101@home:~# hdparm -Tt /dev/sdb

/dev/sdb:

 Timing cached reads:  678 MB in  2.00 seconds = 339.09 MB/sec

 Timing buffered disk reads:  82 MB in  3.04 seconds =  26.93 MB/sec

This is a slower machine (1.5GHz Pentium M) with 1/4 of the RAM of the other machine, which has 2GB, so I suppose that explains why it's slower.

thanks again for the reply. yeah..i guess that i will look for lasie firewire hard drive if possible. it seems more faster than usb2 hard drive. ;) thanks again!