[dm-devel] info on enabling only one path with rdac and DS4700

[Moger, Babu]

> -----Original Message-----
> From: Gianluca Cecchi [mailto:gianluca.cecchi at gmail.com]
> Sent: Monday, November 28, 2011 10:05 AM
> To: device-mapper development
> Subject: Re: [dm-devel] info on enabling only one path with rdac and
> DS4700
> 
> On Mon, Nov 28, 2011 at 3:46 PM, Moger, Babu wrote:
> >> 3) Based on messages during failover, is it true that I can avoid
> >> explicitly put scsi_dh in initrd?
> >> If I create initrd this way:
> >> mkinitrd /boot/initrd-$(uname -r)-scsi_dh.img $(uname -r) --
> >> preload=scsi_dh_rdac
> >> I get this difference:
> >> [root at testserver ~]# diff /tmp/new/init /tmp/current/init
> >> 44,51d43
> >> < echo "Loading scsi_mod.ko module"
> >> < insmod /lib/scsi_mod.ko
> >> < echo "Loading sd_mod.ko module"
> >> < insmod /lib/sd_mod.ko
> >> < echo "Loading scsi_dh.ko module"
> >> < insmod /lib/scsi_dh.ko
> >> < echo "Loading scsi_dh_rdac.ko module"
> >> < insmod /lib/scsi_dh_rdac.ko
> >> 62a55,58
> >> > echo "Loading scsi_mod.ko module"
> >> > insmod /lib/scsi_mod.ko
> >> > echo "Loading sd_mod.ko module"
> >> > insmod /lib/sd_mod.ko
> >>
> >> or will it help in any way?
> >
> > Having scsi_dh_rdac in initrd will help to get rid of the initial I/O
> errors you are seeing.
> >
> 
> Actually not.... see screen shots of console start at
> https://docs.google.com/open?id=0BwoPbcrMv8mvMWRlYmVhM2MtY2JkYi00ZDMzLW
> IxMWMtMDM0YzZjMWU0NGE1
> and
> https://docs.google.com/open?id=0BwoPbcrMv8mvM2RjMDg1MWUtYzVmZC00OTA1LT
> ljNjAtZGZmMjM5NDlhYTI4
> and also dmesg giving for example for sdb and sdc:

Looks like there is something else going on here.

> 
> scsi 3:0:0:1: rdac: LUN 1 (unowned)

This is when handler is loaded.  Looks like your passive paths were detected first.
>From now on, I/Os coming on to sdb will be silenced and will not got to target. That is not happening.

What is the kernel level. I remember there was an issue. It was fixed later by this commit..
http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=commitdiff;h=5a36756b8b3d7178d9c101d1e2a7a83fd7b17706



> sdb : very big device. try to use READ CAPACITY(16).
> SCSI device sdb: 7320494080 512-byte hdwr sectors (3748093 MB)
> sdb: Write Protect is off
> sdb: Mode Sense: 77 00 10 08
> SCSI device sdb: drive cache: write back w/ FUA
> sdb : very big device. try to use READ CAPACITY(16).
> SCSI device sdb: 7320494080 512-byte hdwr sectors (3748093 MB)
> sdb: Write Protect is off
> sdb: Mode Sense: 77 00 10 08
> SCSI device sdb: drive cache: write back w/ FUA
>  sdb:<3>Buffer I/O error on device sdb, logical block 0
> Buffer I/O error on device sdb, logical block 0
> Buffer I/O error on device sdb, logical block 0
> Buffer I/O error on device sdb, logical block 0
> Buffer I/O error on device sdb, logical block 0
> Buffer I/O error on device sdb, logical block 0
> Buffer I/O error on device sdb, logical block 0
> Dev sdb: unable to read RDB block 0
> Buffer I/O error on device sdb, logical block 0
> Buffer I/O error on device sdb, logical block 0
>  unable to read partition table
> sd 3:0:0:1: Attached scsi disk sdb
>   Vendor: IBM       Model: 1814      FAStT   Rev: 0916
>   Type:   Direct-Access                      ANSI SCSI revision: 05
> scsi 3:0:1:1: rdac: LUN 1 (owned)
> scsi 3:0:1:1: rdac: LUN 1 (owned)
> sdc : very big device. try to use READ CAPACITY(16).
> SCSI device sdc: 7320494080 512-byte hdwr sectors (3748093 MB)
> sdc: Write Protect is off
> sdc: Mode Sense: 77 00 10 08
> SCSI device sdc: drive cache: write back w/ FUA
> sdc : very big device. try to use READ CAPACITY(16).
> SCSI device sdc: 7320494080 512-byte hdwr sectors (3748093 MB)
> sdc: Write Protect is off
> sdc: Mode Sense: 77 00 10 08
> SCSI device sdc: drive cache: write back w/ FUA
>  sdc: unknown partition table
> sd 3:0:1:1: Attached scsi disk sdc
> ...
> GSI 23 sharing vector 0x72 and IRQ 23
> ACPI: PCI Interrupt 0000:04:00.0[A] -> GSI 17 (level, low) -> IRQ 114
> eth0: Broadcom NetXtreme II BCM5708 1000Base-SX (B2) PCI-X 64-bit
> 133MHz found at mem da000000, IRQ 114, node addr 00215e2fd0e2
> ACPI: PCI Interrupt 0000:06:00.0[A] -> GSI 19 (level, low) -> IRQ 90
> eth1: Broadcom NetXtreme II BCM5708 1000Base-SX (B2) PCI-X 64-bit
> 133MHz found at mem d8000000, IRQ 90, node addr 00215e2fd0e4
> printk: 69 messages suppressed.
> Buffer I/O error on device sdb, logical block 0
> ...
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> device-mapper: multipath: version 1.0.6 loaded
> device-mapper: multipath: Using scsi_dh module scsi_dh_rdac for
> failover/failback and device management.
> device-mapper: multipath round-robin: version 1.0.0 loaded
> printk: 4 messages suppressed.
> Buffer I/O error on device sdb, logical block 915061759
> ...
> 
> So if I have to get yet the I/O errors, having no advantage, I'd
> prefer to stay stick with the default initrd...
> 
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