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Old 11-16-2010
kopper kopper is offline
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Storage from SAN

hi guys

I installed Centos 5.5 (local disk). I am using 2 HBAs
Now I mapped 5 LUNs from a Storage.
I will be using LVM

just to test I assigned a LUN I've read I have to use multipath to avoid my Centos see the LUN twice

I enabled mdmpd and multipathd...

something else I should do?



by the way I added this LUN 5G but when I boot the server I get these errors those are about sdb BUT when I showed the LUN to the server
fdisk -l only showed me /dev/sdc ???? is the multipathd working?

HTML Code:
end_request: I/O error, dev sdb, sector 0
Buffer I/O error on device sdb, logical block 0
Buffer I/O error on device sdb, logical block 1
Buffer I/O error on device sdb, logical block 2
Buffer I/O error on device sdb, logical block 3
end_request: I/O error, dev sdb, sector 0
Buffer I/O error on device sdb, logical block 0
end_request: I/O error, dev sdb, sector 10485752
Buffer I/O error on device sdb, logical block 1310719
end_request: I/O error, dev sdb, sector 10485752
Buffer I/O error on device sdb, logical block 1310719
end_request:

thanks a lot

Last edited by kopper; 11-16-2010 at 01:53 PM..
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Old 11-16-2010
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Do you happen to have a SAN storage array that has two controllers (active/passive)? Then these messages are usually normal and it indicates that it senses a LUN on the passive controller but cannot read from it. Some arrays can be configured so that they can reroute requests directed at the passive controller to the active controller, so that the host gets proper answers..
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Old 11-16-2010
kopper kopper is offline
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the weird thing is I still see errors after installing and configuring multipath

3.1.*Setting Up DM-Multipath

any idea?
thanks a lot
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Old 11-16-2010
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If what I wrote above applies to your situation, the messages are perhaps from the boot phase before multipath kicks in. What is the output of multipath -l and multipath -ll ?
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Old 11-17-2010
kopper kopper is offline
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well that's the thing I read in other post that those are since the multipath is not started during bootup

but I just got home and I found these

kernel: printk: 20 messages suppressed.
kernel: Buffer I/O error on device sdc, logical block 0
kernel: Buffer I/O error on device sdc, logical block 0
kernel: Buffer I/O error on device sdc, logical block 14417919
kernel: Buffer I/O error on device sdc, logical block 0
kernel: Buffer I/O error on device sdd, logical block 0
kernel: Buffer I/O error on device sdd, logical block 0
kernel: Buffer I/O error on device sdd, logical block 14417919
kernel: Buffer I/O error on device sdd, logical block 0
kernel: Buffer I/O error on device sdf, logical block 0

and I left this system 4 hours ago and still getting these messages well those above are the only ones

I get the point during boot up even when the boot up process is slow because of those messages I don't know why while the server is up and running

---------- Post updated at 01:49 PM ---------- Previous update was at 12:37 AM ----------

is there a way to avoid multipath be sensing the passive paths?
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Old 11-17-2010
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Did you setup multipath.conf correctly? I would contact your San Storage Array vendor for recommended settings.
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Old 11-17-2010
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like I said I configured it as stated above

3.1.*Setting Up DM-Multipath

and I left all other conf by defaault
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