On 07/17/2012 11:11 AM, James Bottomley wrote: > On Tue, 2012-07-17 at 10:54 +0200, Paolo Bonzini wrote: >> Il 17/07/2012 10:40, James Bottomley ha scritto: >>>>> >>>>> It's not specific to virtio-scsi, in fact I expect that virtio-scsi will >>>>> be almost always used with non-removable disks. >>>>> >>>>> However, QEMU's SCSI target is not used just for virtio-scsi (for >>>>> example it can be used for USB storage), and it lets you mark a disk as >>>>> removable---why? because there exists real hardware that presents itself >>>>> as an SBC removable disk. The only thing that is specific to >>>>> virtualization, is support for online resizing (which generates a unit >>>>> attention condition CAPACITY DATA HAS CHANGED). >>> So what's the problem? If you're doing pass through of a physical disk, >>> we pick up removable from its inquiry string ... a physical removable >>> device doesn't get resized. If you have a virtual disk you want to >>> resize, you don't set the removable flag in the inquiry data. >> >> In practice people will do what you said, and it's not a problem. >> >> However, there's nothing that prevents you from running qemu with a >> removable SCSI disk, and then resizing it. I would like this to work, >> because SBC allows it and there's no reason why it shouldn't. > > There's no such thing in the market today as a removable disk that's > resizeable. Removable disks are for things like backup cartridges and > ageing jazz drives. Worse: most removeable devices today are USB card > readers whose standards compliance varies from iffy to non existent. > Resizeable disks are currently the province of storage arrays. > Ho-hum. I beg to disagree. drivers/scsi/aacraid/aachba.c:2266 /* Do not cache partition table for arrays */ scsicmd->device->removable = 1; To the extend of my knowledge aacraid does this _precisely_ to allow for resizing; in effect every open() will trigger a device revalidation. So I guess by just setting the 'removable' flag you should be okay. You might need to remount it, but that's another story. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- 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
