From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lidong Zhong Date: Fri, 26 Sep 2014 11:21:33 +0800 Subject: [PATCH] pvcreate: check the label after writing In-Reply-To: <5423D42C.60106@redhat.com> References: <1411611632-2856-1-git-send-email-lzhong@suse.com> <5423C9A6.8000304@redhat.com> <5423D42C.60106@redhat.com> Message-ID: <1411701693.1629.3.camel@suse.site> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi list, > Dne 25.9.2014 v 09:52 Zdenek Kabelac napsal(a): > > Dne 25.9.2014 v 04:20 Lidong Zhong napsal(a): > >> Some device will place metadata area at the beginning part and writing > >> label may fail.Take our test for example, when running pvcreate on a CDL > >> formatted DASD device(without partition), it shows successfully create > >> a pv, but the label is not written on the second sector and pvs shows > >> nothing. Although it is not supposed to run lvm on dasd device, it's a > >> friendly behavior to check the label and return error if it fails. > > > > Hmm - if device drive tells you - it has accepted and written some bytes > > on your storage device - they really should be written there. > > > > So IMHO driver should not lie and reject write request with error ? > > > > Otherwise you would need to validate every single written byte by LVM ? > > > > Maybe DASD devices should by automatically ignored by lvm filtering > > as unusable device for PV (just like i.e. too small devices) > > It looks like DASD device is somehow supported by 'parted' > > And there are some very 'innovative' ways how to work with this device and > detect where the write is actually allowed/supported. > > So it seems like lvm2 would need to learn those bits on how to manipulate DASD > devices. > > And also tools like blkid then needs to look at proper places how to recognize > such device's signature. > > Anyway - the patch you've proposed is likely not valid. > > Device driver for DASD should reject write attempt to privileged disk area > with 'error'. > > It would be probably fair to disable/ignore DASD device in lvm2 for now - > since we clearly do not understand layout of this device and try to store PV > header into wrong place - and someone needs to write handled for this devices > to reenable support for it. > That's reasonable. we added DASD device in the filter to fix this problem. Thank you > There is BZ http://bugzilla.redhat.com/show_bug.cgi?id=1058326 > which is likely related to the same issue. > > Zdenek > > -- > lvm-devel mailing list > lvm-devel at redhat.com > https://www.redhat.com/mailman/listinfo/lvm-devel > -- Best regards, Lidong