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
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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.

--
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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
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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

--
Digimer
Papers and Projects: https://alteeve.com


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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.
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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

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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.
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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.
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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.





--
john r pierce N 37, W 122
santa cruz ca mid-left coast

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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 /var
>
> adds 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


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