T. Horsnell wrote:
T. Horsnell wrote:
What's the situation with 'raw' and FC3?
I want to get raw access to disks for test
purposes but 'man raw' and 'whereis raw'
show nothing.
Same as for the rest of Linux: you can access a raw partition as
/dev/hdXY or /dev/sdXY (depending on technology), where X is a letter
and Y a number. So the first partition of your first IDE disk is
/dev/hda1.
To refer to the whole disk, use /dev/hdX or /dev/sdX.
Please note: get this wrong and you could delete your whole system. Be
careful. Use backups or a separate test system.
Now the real question: what exactly are you trying to do, and why?
If you just want to see how fast your hard disk goes, try
hdparm -t /dev/hda
(or whatever).
Hi James,
Maybe I should have said direct I/O instead of raw. I discovered
the O_DIRECT option to open(2) over the weekend and have been busy
trying to use it.
What I want to do (and what I have been doing on my Alpha system)
is to thrash any new disk I plug in to my SCSI bus, before putting
it to general use. I do this using a long test (at least 48 hours)
of write/read/verify, of records full of random data, of random length,
to random positions on the disk. I want to avoid the cache (which doesnt
happen if I use /dev/sd?) hence the 'raw' requirement.
And, joy of joys, I can now even use smartctl to monitor the disk
health in the process. Its interesting to see the temperature
rise as the disk starts to work hard...
I hadnt heard of hdparm - what a useful tool. It shows buffered
read rates on my 140GB 10Krpm SCSI drives of 75MByte/sec, but on my new
300GB 10Krpm one, I only get 65MBytes/sec. They're all Seagate - and
all < 3 months old. Strange that.
Have you tried iozone? http://www.iozone.org
----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer rstevens@xxxxxxxxxxxxxxx -
- VitalStream, Inc. http://www.vitalstream.com -
- -
- IGNORE that man behind the keyboard! -
- - The Wizard of OS -
----------------------------------------------------------------------
