On 22 feb 2010, at 21.28, Miles Nordin wrote: >>>>>> "rs" == Ragnar Sundblad <ra...@csc.kth.se> writes: > > rs> But are there any clients that assume that an iSCSI volume is > rs> synchronous? > > there will probably be clients that might seem to implicitly make this > assuption by mishandling the case where an iSCSI target goes away and > then comes back (but comes back less whatever writes were in its write > cache). Handling that case for NFS was complicated, and I bet such > complexity is just missing without any equivalent from the iSCSI spec, > but I could be wrong. I'd love to be educated.
Yes, this area may very well be a mine field of bugs. But this is not a new phenomenon, it is the same with SAS, FC, USB, hot plug disks, and even eSATA (and I guess with CD/DVD drives also with SCSI with ATAPI (or rather SATAPI (does it have a name?))). I believe the correct way of handling this in all those cases would be having the old device instance fail, the file system being told about it, having all current operations fail and all open files be failed. When the disk comes back, it should get a new device instance, and it should have to be remounted. All files will have to be reopened. I hope no driver will just attach it again and happily just continue without telling anyone/anything. But then again, crazier things have been coded... > Even if there is some magical thing in iSCSI to handle it, the magic > will be rarely used and often wrong until peopel learn how to test it, > which they haven't yet they way they have with NFS. I am not sure there is anything really magic or unusual about this really, but I certainly agree that it is a typical thing that might not have been tested thoroughly enough. /ragge _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
