Topic: Can I add two disks (SATA) for raid1 to a single disk (IDE) system?

[tlicht]

Hi,

I have set up an SME 7.3 server and configured it except for my planned ibays on a single IDE disk. Can I add two unused SATA disks and configure them to raid1 and put the ibays on that raid?
The SATA disks show up in fdisk but they are not partitioned and formatted yet.  My thought is that if a catastrophy occurs all my data would still be on at least one of the SATA disks. Which filesystem would make them readable by XP in such a case?

Has somebody tried this before?

[SoftDux]

You should be able todo this, although it's not 100% recommended, since sme handles a lot of stuff on the system.

For instance, if you want to mount this drive, you'd need to do it manualy in /etc/fstab. And if you want to share it over the LAN, again you'd have to manually add it to /etc/samba/smb.conf

[tlicht]

Thanx,

Adding the required mounting and sharing instructions to the two config files is a one time task - or am I miistaken?

A more serious problem might be if this would affect the upgrade/update behaviour of the server.

[idp_qbn]

I think you are going to have problems. SME is designed to be a 2-disk (identical disks) software RAID1 system. ie everything on the first disk is mirrored onto the second disk - or a 4 (or 5 or 6)-disk RAID5

A 1-disk SME server is treated by the OS as a "degraded array" - it still runs because that is what it is supposed to do until you replace the "missing" 2nd disk.

You are proposing (I think) to try to develop a SME server with 1-disk for OS and a seperate 2-disk RAID1 for the Ibays. This is not the way SME works, so upgrading will be difficult.

If you have 2 identical SATA disks, install your server and its Ibays on them and let it run as a mirrored RAID1 system as it is designed to be.

If you want to have 3 disks, it will be installed as a RAID1 system with a "spare" disk. Some people use this spare as a backup by swapping out one of the active mirrored disks and replacing it with the 3rd disk (I think you have to erase Disk 3 before you do this, but I am not sure) and making this a weekly practice, so you have an active RAID1 2-disk system and a spare disk with last week's system and data on it in case of emergencies. If you want to try this THE 3 DISKS MUST BE IDENTICAL IN SIZE. They can be IDE and SATA mix.

Remember, if you deviate from the standard system and tested addons/contribs,
1) you are on your own as far as help goes AND
2) it may (probably will) get clobbered when there is a software update anyway.

I suggest you read the documentation on RAID : http://wiki.contribs.org/Raid
I also suggest you read the rest of the Administration manual : http://wiki.contribs.org/SME_Server:Documentation:Administration_Manual so you can get a better feel of what SME is about and how it works.

Cheers

Ian

[SoftDux]

I don't think that's TOTALLY correct.

True, sme wants RAID to be setup, but will work perfectly fine with just 1 disc, as you said in degraded RAID.

Adding more seperate discs to the sytem, and manually mounting them will not interfere with sme at all. It's like having a few USB / e-sata connected HDD's connected to it and using them permanently. Upgrades won't interfere either, since sme only updates itself, it won't update stuff on disks which are not part of the RAID setup.

And I don't see how this will be a problem in terms of support. If he gets a problem on the seperate RAID system, he's either get no support or at least a little support. But support on the sme installation itself  won't make a difference.

I currently run such a setup, purely cause I didn't have enough space to backup all the data on the current HDD's that I have, and setup sme on it's own 3 HDD's with RAID + 1 spare.

[SoftDux]

Thanx,

Adding the required mounting and sharing instructions to the two config files is a one time task - or am I miistaken?

A more serious problem might be if this would affect the upgrade/update behaviour of the server.

If you add the mount point to /etc/fstab, then it's a 1time thing. I would suggest you mount this RAID array on /mnt or something like that, and not /home as sme use this internally. Adding the samba mount stuff won't be a problem though, but everytime you want to share something new, you'd have to manually add it

[Reinhold]

tlicht: YES ... if you know how to do it
(fdisk with "fd", assemble mdX, format, mount ...)

In general:

http://wiki.contribs.org/AddExtraHardDisk

...explains it all, is updated and completely valid
(just that tlicht needs to form /dev/mdX instead of real hardware /dev/hdX used in the wiki)


BUT: Why don't you just:
login as admin and select "5. Manage disk redundancy"
... in result you will have a system that will even have the SME system fully operational on two independent disks
(no need to make it readable with something else ...)
...now if you than add your 3rd disk as a spare - SME will send you an Email in case one of the (always two operational) disks has failed and automatically copy "live" all your system _and_ data from the (still) functional disk to that 3rd 'spare' disk...
HOW'S that for safety?

Regards
Reinhold

[tlicht]

Thank you again Ray,

I am deeply impressed by your thorough insight in linux in general and SME in particular.
I followed your advice!  The original IDE disk is gone and SME 7.3 is running along happily on the two SATAs. I'll add a third one later. I am a little confused though - I imagined that SME always created three partitions: md0, md1 and md2. I seem only to have md1 and md2 - should I worry?

[raem]

tlicht

I imagined that SME always created three partitions: md0, md1 and md2. I seem only to have md1 and md2 - should I worry?

That's how it's done on sme7.x.