10 More Discussions You Might Find Interesting
1. Linux
I have a freshly installed Oracle Linux 7.1 ( akin to RHEL ) server.
However after installing some Oracle software, I have noticed that my hard disk light is continually on and the system performance is slow.
So I check out SAR and IOSTAT
lab3:/root>iostat
Linux... (2 Replies)
Discussion started by: jimthompson
2 Replies
2. UNIX for Dummies Questions & Answers
In a SCO Unix shop, I am working on the following script to move any file to its same location on the target machine (called 'othersy' here):
pwd=`pwd`
for i in "$@"
do
echo " $i "
if ; then echo 1; else echo 0; fi
rcp -p $i othersy:$pwd/$i
echo "Finished with ^ If I find a file... (4 Replies)
Discussion started by: wbport
4 Replies
3. Solaris
Hello,
we have a machine with Solaris Express 11, 2 LSI 9211 8i SAS 2 controllers (multipath to disks), multiport backplane, 16 Seagate Cheetah 15K RPM disks.
Each disk has a sequential performance of 220/230 MB/s and in fact if I do a
dd if=/dev/zero of=/dev/rdsk/<diskID_1> bs=1024k... (1 Reply)
Discussion started by: golemico
1 Replies
4. Solaris
What tools/utilities do you use to generate metrics on disk i/o throughput on Solaris. For example, if I want to see the i/o rate of random or sequential r/w. (2 Replies)
Discussion started by: dangral
2 Replies
5. Red Hat
Running CentOS 5.5:
I've come across a relatively recent problem, where in the last 2 months or so, the root disk goes to 99% utilization for about 20 seconds when a user logs in. This occurs whether a user logs in locally or via ssh. I have tried using lsof to track down the process that is... (5 Replies)
Discussion started by: dangral
5 Replies
6. Red Hat
I am getting absolutely dreadful iowait stats on my disks when I am trying to install some applications.
I have 2 physical disks on which I have created 2 separate logical volume groups and a logical volume in each. I have dumped some stats as below
My dual core CPU is not being over utilised... (3 Replies)
Discussion started by: jimthompson
3 Replies
7. AIX
I'm search for a disk exerciser / load tool like iometer, iozone, diskx for IBM AIX 5.2 and 5.3
Because of a very bad disk performance on several AIX systems, I need to have a tool which is able to generate a disk load on my local and SAN disks.
Does somebody knows a kind of tool which is... (5 Replies)
Discussion started by: funsje
5 Replies
8. AIX
Hello,
I have a aix 570 system with san disk. I do write test of performance
in a lv with four disk. While the test I run filemon tools for trace
the disk activity. The outputs of filemon are at the en of this message. I
see my lV(logical volume) throughput at 100 meg by second. 2 of 4
disk... (0 Replies)
Discussion started by: Hugues
0 Replies
9. AIX
Can I change any AIX System paramerter for speeding the data Disk performance?
Currently it slows with writing operations. (1 Reply)
Discussion started by: gogogo
1 Replies
10. Filesystems, Disks and Memory
I have some questions regarding disk perfomance, and what I can do to make it just a little (or much :)) more faster.
From what I've heard the first partitions will be faster than the later ones because tracks at the outer edges of a hard drive platter simply moves faster. But I've also read in... (4 Replies)
Discussion started by: J.P
4 Replies
CCD(4) BSD Kernel Interfaces Manual CCD(4)
NAME
ccd -- Concatenated disk driver
SYNOPSIS
pseudo-device ccd [count]
DESCRIPTION
The ccd driver provides the capability of combining one or more disks/partitions into one virtual disk.
This document assumes that you're familiar with how to generate kernels, how to properly configure disks and pseudo-devices in a kernel con-
figuration file, and how to partition disks.
Note that the 'raw' partitions of the disks must not be combined. Each component partition should be offset at least one cylinder from the
beginning of the component disk. This avoids potential conflicts between the component disk's disklabel and the ccd's disklabel. The kernel
will only allow component partitions of type FS_CCD. But for now, it allows partition of all types since some port lacks support of an on-
disk BSD disklabel. The partition of FS_UNUSED may be rejected because device driver of component disk will refuse it.
In order to compile in support for the ccd, you must add a line similar to the following to your kernel configuration file:
pseudo-device ccd 4 # concatenated disk devices
The count argument is how many ccds memory is allocated for at boot time. In this example, no more than 4 ccds may be configured.
A ccd may be either serially concatenated or interleaved. To serially concatenate the partitions, specify the interleave factor of 0.
If a ccd is interleaved correctly, a ``striping'' effect is achieved, which can increase performance. Since the interleave factor is
expressed in units of DEV_BSIZE, one must account for sector sizes other than DEV_BSIZE in order to calculate the correct interleave. The
kernel will not allow an interleave factor less than the size of the largest component sector divided by DEV_BSIZE.
Note that best performance is achieved if all component disks have the same geometry and size. Optimum striping cannot occur with different
disk types.
Also note that the total size of concatenated disk may vary depending on the interleave factor even if the exact same components are concate-
nated. And an old on-disk disklabel may be read after interleave factor change. As a result, the disklabel may contain wrong partition
geometry and will cause an error when doing I/O near the end of concatenated disk.
There is a run-time utility that is used for configuring ccds. See ccdconfig(8) for more information.
WARNINGS
If just one (or more) of the disks in a non-mirrored ccd fails, the entire file system will be lost.
FILES
/dev/{,r}ccd* ccd device special files.
SEE ALSO
config(1), MAKEDEV(8), ccdconfig(8), fsck(8), mount(8), newfs(8)
HISTORY
The concatenated disk driver was originally written at the University of Utah.
BSD
March 5, 2004 BSD