IMHO, fibre attach (FCP) satisfies the need for fixed-block devices for z/Linux. If you use SCSI/FC disk instead of DASD, you can have 512, 1K, or whatever sector size you want as long as it is supported by the device and the software. Removing the DASD emulation layer from the I/O in z/Linux also reduces CPU utilization.
BTW, there is an interesting preliminary abstract for an upcoming article about SCSI IPL on zSeries in the IBM Journal for Research and Development: http://www.research.ibm.com/journal/abstracts/rd/483/banzhaf.html Scott Ledbetter StorageTek -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of John Ford Sent: Wednesday, February 18, 2004 1:55 PM To: [EMAIL PROTECTED] Subject: Re: dasdfmt with a 1K block size - still not recommde d? On 2/18/2004 1:45 PM Richard Troth wrote: > Good summary and analogy, Jim. > Digging to the underlying *reason*, I believe that the > MVS mindset is that what's physically on disk must match the > logical odd or variable sizes (80 bytes and such). In the MVS world > the concept of disk and the concept of filesystem are blurred. > > Along come new software systems like Linux. Voi-la! there is a > new market for whatever a channel-attched disk is. Now there is > a screaming case for FBA DASD. If this is true, then why doesn't some enterprizing vendor sell disk that emulates FBA devices, to be used by Linux, VSE and VM? > And this ignores the old step children > (VSE and VM) who would have benefitted from FBA decades ago. VSE and VM *did* (and as far as I know, still can) benefit from FBA. -- jcf
