9 More Discussions You Might Find Interesting
1. Solaris
Server Model: T5120 with 146G x4 disks.
OS: Solaris 10 - installed on c1t0d0.
Plan to use software raid (veritas volume mgr) on c1t2d0 disk.
After format and label the disk, still not able to detect using vxdiskadm.
Question:
Should I remove the hardware raid on c1t2d0 first?
My... (4 Replies)
Discussion started by: KhawHL
4 Replies
2. Red Hat
We have configured software based RAID5 with LVM on our RHEL5 servers. Please let us know if its good to configure software RAID on live environment servers. What can be the disadvantages of software RAID against hardware RAID (4 Replies)
Discussion started by: mitchnelson
4 Replies
3. UNIX for Dummies Questions & Answers
Hi
Can someone tell me what are the differences between software and hardware raid ?
thx for help. (2 Replies)
Discussion started by: presul
2 Replies
4. Filesystems, Disks and Memory
Hello,
My company has inherited a Centos based machine that has 7 hard drives and a software based raid system. Supposedly one of the drives has failed. I need to replace the hardrive.
How can I about telling which hard drive needs replacing? I have looked in the logs and there clearly is a... (5 Replies)
Discussion started by: mojoman
5 Replies
5. Red Hat
hi friends,
I am having issues with adding a spare device to a failed array.
I have created RAID 1 with 3 partitions using mdadm command. Later I added a spare with
mdadm --add /dev/md0 /dev/sdb6
This works fine and when I check this with mdadm --detail command it just sits there as a spare... (7 Replies)
Discussion started by: saagar
7 Replies
6. Linux
Hey,
I have worked with Linux for some time, but have not gotten into the specifics of hard drive tuning or software RAID. This is about to change. I have a Dell PowerEdge T105 at home and I am purchasing the following:
1GBx4 DDR2 ECC PC6400 RAM
Rosewill RSV-5 E-Sata 5 bay disk enclosure... (6 Replies)
Discussion started by: mark54g
6 Replies
7. HP-UX
Hi!
A couple of months ago a disk failed in our JBOD cabinett and I have finally got a new disk to replace it with. It was a RAID 0 so we have to create and configure the whole thing again. First we thought of RAID 1+0 but it seems you can't do this with LVM. If you read my last thread, you can... (0 Replies)
Discussion started by: hoff
0 Replies
8. SuSE
Hello Lunix people,
I am looking for Raid software or solution besides Veritas. Veritas has some great software but are way too costly. Does anyone know of good raid software that but NOT Veritas. I need the funcations but not the cost. (7 Replies)
Discussion started by: xtmeisel
7 Replies
9. UNIX for Advanced & Expert Users
Good Morning all,
I just have a quick question, on some systems I am working with Software Raid Level 0 devices.
Yes, I know, this is not a good idea, but it was requested :-(
Now, due to a new requirement, I need to add a second internal disk to the system, but with adding the new disk,... (1 Reply)
Discussion started by: malcom
1 Replies
re(7) Miscellaneous Information Manual re(7)
NAME
re - SWXCR RAID interface
SYNOPSIS
2100 Server Model A500MP DEC SWXCR
controller xcrn at * vector xcintr
device disk renn at xcrn drive nn
DESCRIPTION
The re driver is for the SWXCR RAID Array controller.
The following rules are used to determine the major and minor numbers that are associated with an re type disk. There are two major num-
bers used to represent re disks. The major numbers are 11 for block devices and 44 for character (raw) devices.
The minor number is used to represent both the unit number and partition. A disk partition refers to a designated portion of the physical
disk. To accomplish this reference, the 20-bit minor number is divided into three parts. The lowest six bits of the minor number specify
a disk partition. The partitions use a letter, a through h, for their name.
The next three bits of the minor number specify the RE unit number for a unit attached to an SWXCR controller. The final 11 bits specify
the controller number.
The device special file names associated with re disks are based on conventions that are closely associated with the minor number assigned
to the disk. The standard device names begin with re for block special files and rre for character (raw) special files. Following the re
is the unit number and then a letter, a through h, that represents the partition. Throughout this reference page, the question mark (?)
character represents the unit number in the name of the device special file. For example, re?b could represent re0b, re1b, and so on.
The unit number can be calculated if the major and minor numbers of an re disk are provided. For example, suppose you have a device spe-
cial file rre6a, with a major number of 44 and a minor number of 384. The partition is represented by the lower six bits of the number
384. These lower six bits of the number 384 are 0, which specifies the a partition. The next three bits of the minor number 384 specify
the unit number, which is 6. The next eleven bits specify the controller number, which is zero. Putting these three pieces together
reveals that the major/minor number pair 44/384 refers to the a partition of unit 6 attached to controller number 0.
A disk can be accessed through either the block special file or the character special file. The block special file accesses the disk using
the file system's normal buffering mechanism. Reads and writes to the block special file can specify any size. This capability avoids the
need to limit data transfers to the size of physical disk records and to calculate offsets within disk records. The file system can break
up large read and write requests into smaller fixed size transfers to the disk.
The character special file provides a raw interface that allows for direct transmission between the disk and the user's read or write buf-
fer. A single read or write to the raw interface results in exactly one I/O operation. Consequently, raw I/O may be considerably more
efficient for large transfers.
For systems with RE disks, the first software boot after the system is powered on may take longer than expected. This delay is normal and
is caused by the software spinning up the RE disks.
Disk Support
The RE driver handles all disk drives that can be connected to the SWXCR controller. To determine which drives are supported for specific
CPU types and hardware configurations, see the Installation and Configuration Guide for the StorageWorks RAID Array 200 Subsystem Family.
SWXCR RAID Controllers are viewed in all cases as RE type disks. There are some notable differences that should be taken into considera-
tion when configuring a RAID device: Currently only sector sizes of 512 bytes are supported. Logical Volume sizes are not fixed sizes as
compared to other disk devices. The size of the Logical Volume is configurable based on needs. The dynamic nature of Logical Volume sizes
is dealt with by defining RAID devices as DYNAMIC. Only partitions a, b, c, and g are defined. If necessary, the disklabel(8) command can
be run to change and define partitions for RAID devices.
Usually, the re?a partition is used for the root file system and the re?b partition as a paging area. The re?c partition can be used for
disk-to-disk copying because it maps the entire disk.
The starting location and length (in 512 byte sectors) of the disk partitions of each drive are shown in the following table. Partition
sizes can be changed by using the disklabel(8) command.
SWXCR (RAID) partitions for systems
based on the Alpha AXP architecture
disk start length
re?a 0 131072 re?b 131072 262144 re?c 0 end of media re?d 0 0 re?e 0 0 re?f 0 0
re?g 393216 end of media re?h 0 0
FILES
/dev/re??? /dev/rre??? /etc/disktab
RELATED INFORMATION
disklabel(8), MAKEDEV(8), uerf(8) delim off
re(7)