Dear All I want to install an application on my centos server asking if my server supports RAID . How can I check if my server supports RAID ? Thank you
On 06/23/2012 02:09 AM, hadi motamedi wrote:
Dear All I want to install an application on my centos server asking if my server supports RAID . How can I check if my server supports RAID ? Thank you
Hardware RAID? Ask the company you bought it from.
Software RAID? If you have two or more disks, yes.
On 6/23/12, Digimer lists@alteeve.ca wrote:
On 06/23/2012 02:09 AM, hadi motamedi wrote:
Dear All I want to install an application on my centos server asking if my server supports RAID . How can I check if my server supports RAID ? Thank you
Hardware RAID? Ask the company you bought it from.
Software RAID? If you have two or more disks, yes.
-- Digimer Papers and Projects: https://alteeve.com
Thank you very much for your reply. Sorry I meant software RAID to install the service of RAID how to enable and configure the RAID service. Thank you in advance
On 06/23/2012 02:27 AM, hadi motamedi wrote:
On 6/23/12, Digimer lists@alteeve.ca wrote:
On 06/23/2012 02:09 AM, hadi motamedi wrote:
Dear All I want to install an application on my centos server asking if my server supports RAID . How can I check if my server supports RAID ? Thank you
Hardware RAID? Ask the company you bought it from.
Software RAID? If you have two or more disks, yes.
-- Digimer Papers and Projects: https://alteeve.com
Thank you very much for your reply. Sorry I meant software RAID to install the service of RAID how to enable and configure the RAID service. Thank you in advance
It depends on whether you want to do it during the install of the operating system or after the OS is already installed. It also depends on what kind of array you want to build, how many disks will be in it, how those disks are seen by the OS, etc.
The best thing to do is to search for "building a software raid array in linux". The tool is called 'mdadm', so reading it's man page will help you learn, too.
cheers
On Sat, Jun 23, 2012 at 11:57 AM, hadi motamedi motamedi24@gmail.com wrote:
Thank you very much for your reply. Sorry I meant software RAID to install the service of RAID how to enable and configure the RAID service.
The CentOS 6.2 default kernel and installation provide the mdadm (sw) raid functionality.
The following https://raid.wiki.kernel.org/index.php/RAID_setup contain the steps to configure mdadm RAID1.
The key thing would be to decide on the partition sizes and they should be identical on both disks when you create the RAID device(s).
HTH, -- Arun Khan
On 6/23/2012 12:15 AM, Digimer wrote:
Software RAID? If you have two or more disks, yes.
There's no requirement that if you have two disks, they have to be RAIDed together. I frequently build systems with /dev/sda being a lone SATA disk for the OS and apps, with /dev/sdb being a hardware RAID for the real data the system manages. Another pattern I've used is a small CF card for the core OS, and /usr, /home and other bulk users of storage off on a second spinning disk.
A better test is probably "mount | grep md".
Then there's the LVM option, but I can't immediately come up with a one-liner that tells you whether a given LVM disk set is equivalent to software RAID.
And then we can get into more exotic options like btrfs and zfs which are also potentially RAID-like, but not necessarily so.
Warren Young wrote:
On 6/23/2012 12:15 AM, Digimer wrote:
Software RAID? If you have two or more disks, yes.
There's no requirement that if you have two disks, they have to be RAIDed together. I frequently build systems with /dev/sda being a lone SATA disk for the OS and apps, with /dev/sdb being a hardware RAID for the real data the system manages. Another pattern I've used is a small CF card for the core OS, and /usr, /home and other bulk users of storage off on a second spinning disk.
A better test is probably "mount | grep md".
cat /proc/mdstat <snip> mark
On 6/25/12, Warren Young warren@etr-usa.com wrote:
Then there's the LVM option, but I can't immediately come up with a one-liner that tells you whether a given LVM disk set is equivalent to software RAID.
LVM has a mirroring option but from, possibly outdated, reading a couple of years back, it is not as smart as md raid when it comes to using both disks to speed up reading and will only read from one disk.
On Tue, Jun 26, 2012 at 03:10:30AM +0800, Emmanuel Noobadmin wrote:
On 6/25/12, Warren Young warren@etr-usa.com wrote:
Then there's the LVM option, but I can't immediately come up with a one-liner that tells you whether a given LVM disk set is equivalent to software RAID.
LVM has a mirroring option but from, possibly outdated, reading a couple of years back, it is not as smart as md raid when it comes to using both disks to speed up reading and will only read from one disk.
Also, nobody uses it. If you hit a problem, you are completely on your own. I thought it would be more simple to have only one abstraction layer; Nope. Use md and lvm on top of the md.
On 06/25/12 12:14 PM, Luke S. Crawford wrote:
Also, nobody uses it. If you hit a problem, you are completely on your own. I thought it would be more simple to have only one abstraction layer; Nope. Use md and lvm on top of the md.
they really should be better integrated, like the way LVM and JFS are integrated on AIX.
# chfs -a size=+2G /var
adds 2GB to /var, online, automatically. grows the logical volume and resizes the file system, all at once.
Am 25.06.2012 21:51, schrieb John R Pierce:
On 06/25/12 12:14 PM, Luke S. Crawford wrote:
Also, nobody uses it. If you hit a problem, you are completely on your own. I thought it would be more simple to have only one abstraction layer; Nope. Use md and lvm on top of the md.
they really should be better integrated, like the way LVM and JFS are integrated on AIX.
# chfs -a size=+2G /varadds 2GB to /var, online, automatically. grows the logical volume and resizes the file system, all at once.
Don't know where software RAID comes into play on AIX, but what is the difference of that command above to this one on CentOS 6?
# lvresize -L+2G -r VG_sys/LV_var
Alexander
On 06/25/12 1:10 PM, Alexander Dalloz wrote:
they really should be better integrated, like the way LVM and JFS are
integrated on AIX.
# chfs -a size=+2G /varadds 2GB to /var, online, automatically. grows the logical volume and resizes the file system, all at once.
Don't know where software RAID comes into play on AIX, but what is the difference of that command above to this one on CentOS 6?
# lvresize -L+2G -r VG_sys/LV_var
software raid in AIX is handled by the LVM layer, and if the LV is configured for mirroring ('copies=2'), then the resized LV will also be mirrored.
does lvresize resize the file system while online? I didn't think it did. the man page for fsadm (referenced in the lvresize man page) says ext2/3/4 is unmounted before resizing. ooops. kind of hard to umount /var !
On 2012-06-25, John R Pierce pierce@hogranch.com wrote:
On 06/25/12 1:10 PM, Alexander Dalloz wrote:
they really should be better integrated, like the way LVM and JFS are
integrated on AIX.
# chfs -a size=+2G /varadds 2GB to /var, online, automatically. grows the logical volume and resizes the file system, all at once.
Don't know where software RAID comes into play on AIX, but what is the difference of that command above to this one on CentOS 6?
# lvresize -L+2G -r VG_sys/LV_vardoes lvresize resize the file system while online? I didn't think it did. the man page for fsadm (referenced in the lvresize man page) says ext2/3/4 is unmounted before resizing. ooops. kind of hard to umount /var !
My man page for fsadm (CentOS 6) implies that you need to provide -e in order for fsadm to umount an ext? filesystem before attempting the resize. So in theory if you don't give -e it should resize while mounted.
--keith
On 06/26/2012 12:50 AM, Keith Keller wrote:
On 2012-06-25, John R Pierce pierce@hogranch.com wrote:
On 06/25/12 1:10 PM, Alexander Dalloz wrote:
they really should be better integrated, like the way LVM and JFS are
integrated on AIX.
# chfs -a size=+2G /varadds 2GB to /var, online, automatically. grows the logical volume and resizes the file system, all at once.
Don't know where software RAID comes into play on AIX, but what is the difference of that command above to this one on CentOS 6?
# lvresize -L+2G -r VG_sys/LV_vardoes lvresize resize the file system while online? I didn't think it did. the man page for fsadm (referenced in the lvresize man page) says ext2/3/4 is unmounted before resizing. ooops. kind of hard to umount /var !
My man page for fsadm (CentOS 6) implies that you need to provide -e in order for fsadm to umount an ext? filesystem before attempting the resize. So in theory if you don't give -e it should resize while mounted.
I know that a combination of lvextend and resize2fs can be done online. I regulary add new virtual disks to guests and then add the space to the root partition in these guests in fact I just added 100G of space to a mongodb VM a few minutes ago. While I haven't used the -r switch yet I would think that it uses the same mechanism and thus should do all its work online as well.
Regards, Dennis
On 6/25/2012 2:10 PM, Alexander Dalloz wrote:
but what is the difference of that command above to this one on CentOS 6?
# lvresize -L+2G -r VG_sys/LV_var
That doesn't resize the filesystem sitting on the LV_var logical volume.
There's a level of non-integration above this, too: when you add a PV to a VG, you have to explicitly resize the VG afterward, before you can resize the LV, so you can resize the FS!
P'tui!
-
Alexander Dalloz -
Arun Khan -
Dennis Jacobfeuerborn -
Digimer -
Emmanuel Noobadmin -
hadi motamedi -
John R Pierce -
Keith Keller -
Luke S. Crawford -
m.roth＠5-cent.us -
Warren Young