Topic: Help needed with this

[Janm]

You have lost sdb in your raid array.

Also, I don't think your raid adapter is supported.  At least it was not supported in SME6 and may still dot be supported.

Paul

Thanks i will do a complete reinstall now to se if thats help
so for a while i have no server and no mail  
and i will try to get the support file *.img for the server from ibms homesite now so it can see the raid

http://www.acnc.com/04_01_00.html


Jan have a nice evening and not to many  
by for now Jan

[Janm]

Hej i am back again  
edited

Grin
regards Jan  

Last login: Sun Apr 16 23:30:31 2006
CentOS release 4.2 (Final) - SME Server 7.0rc1
[root@www ~]# cat /proc/mdstat
Personalities : [raid1] [raid5]
md2 : active raid5 sdc2[2] sdb2[1] sda2[0]
      70878208 blocks level 5, 256k chunk, algorithm 2 [3/3] [UUU]

md1 : active raid1 sdc1[2] sdb1[1] sda1[0]
      104320 blocks [3/3] [UUU]

unused devices: <none>
[root@www ~]#

Jan

[greg]

pfloor wrote:

I don't quite understand what you mean by "equal number of disks"..."Equal" to what? Do you mean "even number of disks" as in 2, 4, 6?

RAID1 can be set up on 2 or more disks of equal size. If you use different size disks, your array will be the size of the smallest disk. You can use 3, 4, 5, 11, 99 disks, it doesn't matter as they will all just mirror each other. Adding disks only adds redundancy and not storage space.

Traditionally RAID1 is set up on a pair of drives but can be set up on any number of drives and using any of the disks above the initial 2 disks as either "active" disks or "spare" disks in any combination.

Sure - I mean even. And I also know that it's just mirroring.
RAID1 is usually made pairwise with the same size disks. It can also be striped to RAID1+0 or RAID10.

/G

[pfloor]

Sure - I mean even. And I also know that it's just mirroring.
RAID1 is usually made pairwise with the same size disks.

So then, is an *even* number of disks "usual" or "reqiured"?  You have changed your statement here.

The fact of the matter here is that you stated:

"pfloor, true - but real raid1 requires an equal number of disks. "

and this statement is just down right untrue.  Raid1 only has 1 real "requirement" and that would be that the raid1 array contains at least 2 partitions (not even 2 seperate disks).  You can mirror 2 (or more) partitions on the same disk if you really wanted to.  Logic tells us however that would not be a very good thing to do.

Mirroring just gives us a better chance of NOT losing our data. Lets say that 1 in 500 drives failed within 3 years.  That would mean that you have a 1 in 500 chance of losing your data.

1 disk = 1 in 500 chance of total data loss
2 disk mirror = 1 in 250,000 chance of total data loss
3 disk mirror = 1 in 125,000,000 chance of total data loss
4 disk mirror = 1 in 62,500,000,000 chance of total data loss
5 disk mirror = 1 in 31,250,000,000,000 chance of total data loss (that is a one 31 quadrillion chance)

Mirroring is the BEST data redundancy for mission critical situations.  In a 5 disk mirror, you would have to have all 5 disks fail all at once to lose your data...This is almost statistically impossible.

In contrast, a raid5 aray (regardless of the number of disks) can only withstand the loss of 1 disk.  This puts the raid5 array at a 1 in 250,000 chance of total data loss.  Redundancy versus performance...You choose.

Now back to the OP's problem...

[pfloor]

[root@www ~]# cat /proc/mdstat
Personalities : [raid1] [raid5]
md2 : active raid5 sdc2[2] sdb2[1] sda2[0]
      70878208 blocks level 5, 256k chunk, algorithm 2 [3/3] [UUU]

md1 : active raid1 sdc1[2] sdb1[1] sda1[0]
      104320 blocks [3/3] [UUU]

unused devices: <none>
[root@www ~]#

Jan

Jan, your hardware raid card is NOT being recognized by SME.  mdstat is the status of the software raid that SME set up during the installation.  It shows 3 drives and 2 partitions on each drive.

Partitions sda1, sdb1 and sdc1 are set up as a raid1 and running fine.  This is where the boot partition is kept so that SME can boot.

Partitions sda2, sdb2 and sdc2 are the rest of the drives set up as a raid5.  This is also running properly.  This is where the rest of the files are being stored.

This is actually 2 seperate raid devices (one raid1 and one raid5) running on the same 3 drives, just different partitions.

SME has taken over your raid controller and is just using it as a plain old disk controller and performing software raid.

If the raid controller was working as a true raid controller, it would just present itself to SME as a single disk and SME would treat it as 1 disk and not 3.

Either you don't have the controller set up correctly or it is what is known as "Fake Raid".  You need to do some research and find out for yourself.

Paul

[greg]

pfloor wrote:

....
1 disk = 1 in 500 chance of total data loss
2 disk mirror = 1 in 250,000 chance of total data loss
3 disk mirror = 1 in 125,000,000 chance of total data loss
4 disk mirror = 1 in 62,500,000,000 chance of total data loss
5 disk mirror = 1 in 31,250,000,000,000 chance of total data loss (that is a one 31 quadrillion chance)
....

OK, you got me on this. I surrender. I was not precise in my statements, and will be silent for now on this....

Also thanks for the lesson. I appreciate that.
However,  unless you have very mission critical data, more than two drives must be unusual - or what? I've never seen it in my career.

Should I take your point of view, that you (when it's just two mirroring RAID1 drives, or a couple using RAID1+0) would prefer RAID5?
In your small calculation above it gives the same possibility of fail as a pair RAID1 consisting of two drives - or, say, 6 drives in RAID1+0 config.

Cheers

/G
[/quote]

[greg]

Jan,

You can try to find a driver here
http://www-306.ibm.com/pc/support/site.wss/document.do?sitestyle=ibm&lndocid=MIGR-55285&velxr-layout=print

However, I'm not sure they work, as the latest OS I see is RHEL 3, and it may be for SATA devices...
Moreover, I'm not sure how to create the driver disks from these files and subsequently use the 'linux dd' option when setting up the system.

Can this actually be done with SME?

Also, if you search the web - you will see several people having your problem.
So - the easiest solution may be to buy a LSI MegaRaid or similar or let SME do the software RAID ...

/G

[pfloor]

Also thanks for the lesson. I appreciate that.
However,  unless you have very mission critical data, more than two drives must be unusual - or what? I've never seen it in my career.

More than 2 drives in a raid1 is VERY unusual but I have seen it in accounting firms.  They are *very* particular about data loss and don't care as much about speed.

Should I take your point of view, that you (when it's just two mirroring RAID1 drives, or a couple using RAID1+0) would prefer RAID5?

I really don't have a preference.  I ran 2 disk raid1 for a long time and felt very secure with it.  I just liked the idea of having "everything" doubled.  I currently run SME7 with a 4 disk raid5.  To be honest, it makes me a bit nervous, probably because I don't know enough about it and I really don't understand how it works...But that in itself is a whole new topic for discussion.

As for the OP's problem.  I looked around at issues revolving around his controller and I am convinced that it is not a real raid card.  Drivers, re-compiling kernels, etc... That card should be invisable to the whole machine and just act like a single drive.  To make it work is going to take cpu resources and he might as well just use the SW raid built into SME7.  SW raid is very good and actually out-performs most "fake raid" cards anyway.

Paul

[Janm]

Thanks again both of you
for your interest in my problems
i did a new install again today with only 2 drive in computer
Thanks again everybody

edited this post has removed the pictures now

all the best from Jan