CentOS 5 :: Cannot Get 1M IO With Block Devices?
Nov 19, 2009
I am trying to do 1Meg IO to one of the block devices but I can only get a maximum of 512K IO size. I can use the corresponding sg device to get 1Meg of IO. I was wondering if anyone knows why 1Meg IO to a block device is being broken down into 2 512K chunks? I have increased the /sys/block/sdg/queue/max_sectors_kb to 16384, but it has made no difference.
My uname is : Linux virgo 2.6.18-128.el5 #1 SMP Wed Jan 21 10:41:14 EST 2009 x86_64 x86_64 x86_64 GNU/Linux
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May 28, 2013
I'm using a Dell SC440 server for this effort. I started with Debian 6.0.7 32 bit i386 version in mid April and everything seemed to go smoothly until the first boot finished, I wanted to look at the hard drive just to see what storage space was left to work with. The drive was not recognized and I could not mount it. The error message was "One or More Block Devices are Holding /dev/dm-0".
I could not find anything on the debian forums that seemed to relate to the error message so Google led me to the same problem on Fedora, Ubuntu and one other distro. I flattened the machine and restarted from scratch. This time using Debian 6.0.7 AMD64 version. The install went well but I had the same problem with the same results. So I started over several more times before the new Debian 7.0 AMD64 version was released. Under Debian 7.0 I not only get the same error message but I also get a message that my video card is not supported under this new version of gnome and sudo does not work.
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Dec 7, 2010
I'm working on a server and noticed that the to RAID5 setup is showing 4 Raid devices but only 3 Total devices. It's on a fully updated CentOS 5 system that only has three SATA drives, as it can not hold anymore. I've done some researching but am unable to remove the fourth device, which is listed as removed. The full output of `mdadm -D /dev/md2` can be see below. I've never run into this situation before.Anyone have any pointers on how I can reduced the Raid Devices from 4 to 3? I have tried
mdadm /dev/md2 -r failed
mdadm /dev/md2 -r detached
but neither work and since there is no block device listed I'm not quite sure how to get things back in sync so it's only seeing the three drives.
/dev/md2:
Version : 0.90
Creation Time : Tue May 25 11:07:04 2010
Raid Level : raid5
[code]....
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Aug 15, 2011
I have created a number of network block devices that I would like to delete, but I have been unable to find any information to do this.
I am using Centos 5.6 and my kernel is 2.6.18-238.el5.
I have been searching the internet for two days now and have noticed some other UNIX systems do have utilities for deleting unwanted devices but nothing for linux.
I created these devices with the vmware supplied PERL script vmware-mount.pl which in turn calls mknod.
The commands would look like:
mknod /dev/nbd0 b 43 0
mknod /dev/nbd1 b 43 1
......
I have tried deleting them from /dev which works temporarily but they come back when I reload the nbd module i.e.
modprobe -r nbd
modprobe nbd
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There is a directory tree for each device under /sys/block and I'm guessing this is how /dev is getting repopulated. I cannot remove the directory trees from /sys/block. I get this when I try:
rm: cannot remove `nbd15/queue/iosched/slice_idle': Operation not permitted
rm: cannot remove `nbd15/queue/iosched/slice_async_rq': Operation not permitted
...... there are 25 lines like this ....
When I do a vgsan I see this:Reading all physical volumes. This may take a while...
/dev/nbd0: read failed after 0 of 4096 at 0: Input/output error
/dev/nbd0: read failed after 0 of 4096 at 2199022141440: Input/output error
and in the messages log I see this:
Aug 15 21:04:06 udon-desktop kernel: nbd15: Attempted send on closed socket
Aug 15 21:04:06 udon-desktop kernel: end_request: I/O error, dev nbd15, sector 0
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Apr 24, 2009
I would like to mount a Xen image, so I can access the files in the Xen guest.
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[Code].....
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On my top right hand corner. No network devices available.
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May 15, 2009
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/dev/sda1 Boot
/dev/sda3 /
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[code].....
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Nov 6, 2010
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[code]...
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[Code]...
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May 22, 2009
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vm1:
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Disk /dev/xvda: 4194 MB, 4194304000 bytes
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[Code].....
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ram: ddr3 crucial 4gb
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ata4.00 : exception Emask 0x0 SAct 0x0 action 0x0 frozen ......
ata4.00 : status: { DRDY }
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Sep 4, 2009
I just downloaded an iso of the latest CentOS dist (5.3) and burned it to disk. I booted from the CD and received the following error:
Memory for crash kernel (0x0 to 0x0) not within permissible range
Illegal mode for this track or incompatible medium -- (asc=0x64, ascq-0x00)
The failed "read 10" packet command was:
Buffer I/O error on device hdd, logical block 176935
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Red Hat nash version 5.1.19.6 starting
Setting up new root fs
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Setting Clock
Starting udev
Loading default keymap (us)
Setting hostname local host.localdomain
Setting up logical volume management
Checking file systems
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I virtualized a PC with VMware vCenter Converter. But when I boot my virtual PC, I have an error.I found this link but I can't mount /dev, /sys and /proc. I have this error message : mount: /dev is not a block device.
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Dec 2, 2010
I'm no expert on DHCP. My problem is that i have a CentOS 5.5 server on which i want to install a DHCP server. I have two NICs where eth0 has access to the internet and where eth1 should act as an DHCP server.
I have installed dhcpd and this is how my dhcpd.conf file looks like.
Code:
ifconfig looks like this
Code:
When i start dhcpd on eth1 i get no error messages but when i connect any devices to eth1 they don't get any IP. I cant find anything in any logs about devices trying to get an IP address. I dont have any firewall rules in iptables.
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