The problem is there is not a single solution to this, so i give you a list of options you have in order of preferability (is this a word? english is not my native language):
SCSI-disk and native SSA-disks (not SSA-RAID-volumes, etc.) have an attribute called "size_in_mb", which you could read. Example: to get the size of hdisk0 you can type (and get this sample information for a 18GB disk)
If the disk in question is in a volume group you can find out with lspv like this (output is exemplary):
you could also use bootinfo, BUT: bootinfo is usually only executable by root, whereas lsattr is executable by everybody AND the bootinfo command won't work on some disks.
Maybe this is the wrong forum to start this debate and I apologize if it is, but I have been wondering for some time which is better to use for a database, raw or filesystem? By better I mean don't just mean better performance but also ease of maintenance, etc.
I know that several years ago it... (5 Replies)
Hi
I have solaris 8 installed on Intel machine. the disk I have is IDE.
I would like to know how can I create a raw partition on an IDE disk.
Regards,
Raja (2 Replies)
Hi,
What is a Raw command and how does it work? We have to print out a large report from our database numerically and wanted to know how it can be done.
:confused: (1 Reply)
The query is as follows :
A typical server configs when using Oracle or any other type of DB is to install the OS + DB binaries on the internal disks of the relevant server e.g.
Disk 1 : OS + SW + DB binaries
Disk 2 : Mirror of disk 1 (used for resiliency)
Then one uses an external array... (1 Reply)
Can you please modify my script. This script is not working
for i in /dev/sdf
do
/bin/raw /dev/raw/`/bin/basename ${i}` ${i}
/bin/sleep 2
/bin/chown orasm:ordba /dev/raw/`/bin/basename ${i}`
/bin/chmod 660... (9 Replies)
Hey friends,
i am trying to set up a raspbian wheezy vm on ma Unbuntu using qemu.
when i try to run the setup command the error is:
i tried to find something here in the forum but did not find anything. i was searching like 15 min pls dont roast me if there is a post explaining it.
:)... (3 Replies)
Discussion started by: LinuxPlayer1809
3 Replies
LEARN ABOUT REDHAT
rawdevices
RAW(8) System Manager's Manual RAW(8)NAME
raw - bind a Linux raw character device
SYNOPSIS
raw /dev/raw/raw<N> <major> <minor>
raw /dev/raw/raw<N> /dev/<blockdev>
raw -q /dev/raw/raw<N>
raw -qa
DESCRIPTION
raw is used to bind a Linux raw character device to a block device. Any block device may be used: at the time of binding, the device
driver does not even have to be accessible (it may be loaded on demand as a kernel module later).
raw is used in two modes: it either sets raw device bindings, or it queries existing bindings. When setting a raw device, /dev/raw/raw<N>
is the device name of an existing raw device node in the filesystem. The block device to which it is to be bound can be specified either
in terms of its major and minor device numbers, or as a path name /dev/<blockdev> to an existing block device file.
The bindings already in existence can be queried with the -q option, with is used either with a raw device filename to query that one
device, or with the -a option to query all bound raw devices.
Once bound to a block device, a raw device can be opened, read and written, just like the block device it is bound to. However, the raw
device does not behave exactly like the block device. In particular, access to the raw device bypasses the kernel's block buffer cache
entirely: all I/O is done directly to and from the address space of the process performing the I/O. If the underlying block device driver
can support DMA, then no data copying at all is required to complete the I/O.
Because raw I/O involves direct hardware access to a process's memory, a few extra restrictions must be observed. All I/Os must be cor-
rectly aligned in memory and on disk: they must start at a sector offset on disk, they must be an exact number of sectors long, and the
data buffer in virtual memory must also be aligned to a multiple of the sector size. The sector size is 512 bytes for most devices.
Use the /etc/sysconfig/rawdevices file to define the set of raw device mappings automatically created during the system startup sequence.
The format of the file is the same used in the command line with the exception that the "raw" command itself is omitted.
OPTIONS -q Set query mode. raw will query an existing binding instead of setting a new one.
-a With -q , specifies that all bound raw devices should be queried.
-h provides a usage summary.
BUGS
The Linux dd (1) command does not currently align its buffers correctly, and so cannot be used on raw devices.
Raw I/O devices do not maintain cache coherency with the Linux block device buffer cache. If you use raw I/O to overwrite data already in
the buffer cache, the buffer cache will no longer correspond to the contents of the actual storage device underneath. This is deliberate,
but is regarded either a bug or a feature depending on who you ask!
AUTHOR
Stephen Tweedie (sct@redhat.com)
Version 0.1 Aug 1999 RAW(8)