Dear Sirs.

I appreciate your response.

Currently the server has set up a Raid-1 with 2 SCSI disks, it adds up to 6 SCSI disks with the following configuration:

- Raid-1 (4 SCSI disks)

- Raid-1 (2 SCSI disks)

Therefore will have 3 SCSI disk arrays.

The server is not configured with LVM.

CentOS 4.7 support this configuration?

Another supplementary question, because CentOS 4.7 only recognizes 273GB if the disk is 300GB?

Thanks

Luis

Date: Tue, 8 Sep 2009 14:14:41 -0400 From: rswwalker@gmail.com To: centos@centos.org Subject: Re: [CentOS] Support for add disk SCSI

On Tue, Sep 8, 2009 at 2:01 PM, Luis campolcr_2505@hotmail.com wrote:

...

Dear Sirs.

I have a ML370 G4 server with 2 disk SCSI Ultra 320 of 300 GB in RAID-1 through a controller and operating system CentOS 4.7.

My question: CentOS 4.7 could support the expansion of capacity by adding 6 disks SCSI Ultra 320 of 300GB in Raid-1?

Sure, create 3 RAID1s (or a RAID5/6/10) on HW or SW then create an LVM VG out of them, create LVs (striped if multiple RAID devices) out of the VG.

I don't know if your using LVM now on the existing RAID1, but I wouldn't just add them to the root VG if you are, which would also give it expanded capacity, as it would make recovery more difficult if you need to put the drives into a new server.

-Ross _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos

_________________________________________________________________ Explore the seven wonders of the world http://search.msn.com/results.aspx?q=7+wonders+world&mkt=en-US&form=...

Thanks for your reply,

The configuration I mentioned implies that each SCSI disk array would be in a new partition?

Regarding the size of the disk because it recognizes only 273GB

thanks

Luis

Date: Tue, 8 Sep 2009 12:54:13 -0700 From: centos@linuxpowered.net To: centos@centos.org Subject: Re: [CentOS] Support for add disk SCSI

Luis campo wrote:

...

Dear Sirs.

I appreciate your response.

Currently the server has set up a Raid-1 with 2 SCSI disks, it adds up to 6 SCSI disks with the following configuration:

• Raid-1 (4 SCSI disks)

• Raid-1 (2 SCSI disks)

Therefore will have 3 SCSI disk arrays.

The server is not configured with LVM.

CentOS 4.7 support this configuration?

Absolutely, if your doing it "online" you'll need to re-scan the scsi bus or manually add the new LUN/ID to the system, what I do is

• cat /proc/scsi/scsi

(take note of the ID string, e.g. Host: scsi0 Channel: 00 Id: 01 Lun: 01 )

If the RAID controller presents the new array as a new LUN then do something like:

echo "scsi add-single-device 0 0 1 2" /proc/scsi/scsi

Will tell the system to scan for LUN #2

If the controller presents the new array as another SCSI ID, then I would use "0 0 2 0" or perhaps 0 0 2 1 as the sequence.

Otherwise you can reboot and the system will detect it automatically.

As for the disk size thing, that is normal, the system is correctly detecting the size.

nate

---

CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos

_________________________________________________________________ Explore the seven wonders of the world http://search.msn.com/results.aspx?q=7+wonders+world&mkt=en-US&form=...

Les Mikesell wrote:

Luis campo wrote:

...

Thanks for your reply,

The configuration I mentioned implies that each SCSI disk array would be in a new partition?

Yes, if you want raid1. Other raid levels or LVM could group them into one.

some confusion here, perhaps. I've noticed that many hardware raid controllers use "raid1" to refer to both raid-1 (2 disks mirrored) and raid-10 (2*N disks mirrored and striped).

with 4 disks in a single raid, you would actually have a raid-10, which is two mirror sets striped together). after building the raid in the disk controller (or if its not a hardware controller, building a software raid with mdadm), you would create a new file system on it with mkfs, then mount it as a directory (adding it to /etc/fstab for permanent use) so you could start putting files on it. I often mount my 'aux' file systems as /u10, /u11, ...

Luis campo wrote:

Thanks for your reply,

we have the idea of having 4 disk in a RAID-1 this is feasible or that we recommend.

again, thats really a raid-10 regardless of what your disk controller calls it.

sure, we do it all the time, mostly for relational databases such as Oracle, where we will use 4 or 6 spindle raid10's as tablespaces (and often many sets of these for a large volume trnasactional database server).

but, whats recommended really depends on what you plan on using it for, and what your IO performance requirements are.

Alan Hodgson wrote:

On Tuesday 08 September 2009, Luis campo lcr_2505@hotmail.com wrote:

...

Another supplementary question, because CentOS 4.7 only recognizes 273GB if the disk is 300GB?

CentOS recognizes the full size of the disk. Your disconnect is between what the manufacturer sells as 300GB, and the actual size of the disk.

disk drives are sold by decimal gigabytes, so "300GB" is 300,000,000,000 bytes.

software tends to use binary gigabytes, so 273GB is 273 * 1024 * 1024 * 1024, or 293,131,517,952 bytes, which is *about* 300GB (decimal)

btw, in an earlier email, I believe you said you had a HP DL-something.... if that has an HP "SmartArray" hardware raid controller, its quite likely using the 'cciss' driver (/dev/cciss/c0t0d0 ..) and I'm not sure the previously-offered advise of cat "...." > /proc/scsi/scsi is applicable.