[dm-devel] [PATCH] libmultipath: Increase SERIAL_SIZE to 256 bytes

[Martin Wilck]

On Tue, 2018-08-28 at 16:34 -0500, KyleMahlkuch wrote:
> Certain IBM FlashSystem LUNs can return up to 85 bytes of serial
> number in the Unit Serial Number VPD page, which is larger than
> the current SERIAL_SIZE definition of 65 bytes. Since the max
> size of this field does not appear to be defined in SPC, increasing
> to 256 bytes should hopefully prevent us from hitting this
> in future.
> 

I'm not against it, but would 128 be enough, too? That's what we use
for WWID.

> This is an example of a serial number from a FlashSystem:
> Unit serial number VPD page:
> Unit serial number:
> 3321360050764008101AB300000000000012204214503IBMfcp

$ echo 3321360050764008101AB300000000000012204214503IBMfcp | wc -c
52

It looks as if 65 bytes would be sufficient for _this_ serial number.
Is there excessive space padding at the end, maybe? Run

sg_vpd -p sn -r $DEV | hexdump -C 

> 
> Before this patch multipath returns the error:
> Jul 17 11:24:58 | vpd pg80 overflow, 85/65 bytes required
> 
> After the patch is applied the error no longer occur.
> 
> Signed-off-by: Kyle Mahlkuch <kmahlkuc at linux.vnet.ibm.com>
> ---
>  libmultipath/structs.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Thanks,
Martin	

-- 
Dr. Martin Wilck <mwilck at suse.com>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
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