Hi Kay, Thank you for looking at it. (2011/06/17 2:20), Kay Sievers wrote: > On Thu, Jun 16, 2011 at 19:09, Kay Sievers <kay.sievers@xxxxxxxx> wrote: >> On Thu, Jun 16, 2011 at 18:25, James Bottomley >> <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: >>> On Thu, 2011-06-16 at 09:14 -0700, Greg KH wrote: >>>> All userspace naming will be taken care of by the usual udev rules, so >>>>> for disks, something like /dev/disk/by-preferred/<fred> which would be >>>>> the usual symbolic link. >>>> >>>> No, udev can not create such a link after the preferred name is set, as >>>> it has no way of knowing that the name was set. >>> >>> It can if we trigger a uevent. Note: I'm not advocating this ... I'd be >>> equally happy having whatever sets the kernel name create the link (or >>> tickle udev to create it). We definitely require device links, though, >>> to get this to work. > > Guess all that would work now, including mount(8) not canonicalizing. > What would happen if we mount: > /dev/disk/by-pretty/foo > and some tool later thinks the pretty name should better be 'bar', it > writes the name to /sys, we get a uevent, the old link disappears, we > get a new link, mount has no device node anymore for the mounted > device ... > > So we basically get a one-shot additional pretty name? Guess, the > _single_ name changed anytime later just asks for serious problems. We > need to set it very early to be really useful, but how, where is it > coming from? > If we can avoid serious problems, I will implement preferred name as write once. I have two idea for work preferred name from the very first steps during early boot in initramfs. 1. I think we can provide udev rules for preferred name in initramfs. 2. (option) I consider using user-defined name for the LUNs(*) because it is possible to get the name in initramfs. The user store preferred name in LUNs by sg command if available. (*) Hannes say: > Well, certain storage arrays are able to print out the user-defined name for the LUNs: > > # sg_vpd -p 0xc8 /dev/sdc > Extended device identification (RDAC) VPD Page: > Volume Unique Identifier: 60080e50001bf1f0000005004ddb05a4 > Creation Number: 1280, Timestamp: Tue May 24 03:11:00 2011 > Volume User Label: mas-1 > Storage Array Unique Identifier: 60080e50001bf1f0000000004d418973 > Storage Array User Label: LSI-SAS-DIF > Logical Unit Number: 0000000000000000 > > where the 'Volume User Label' is the name the administrator has given to the LUN on the storage array. Thanks, -- Nao NISHIJIMA Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., YOKOHAMA Research Laboratory Email： nao.nishijima.xt@xxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
