Second time I am sending this. Weird interaction with Droid GMail applet since Samir's post appeared (to GMail) to be spam (but Mark's did not, duh).
Anyway, LDL is kind of a misnomer. It simply means that the disk is all blocked consistently at 4K, which is more good than bad. The only downside to LDL is that z/OS does not grok it. No great loss. (No reason z/OS could not grow up and get a driver or do SSCH to an LDL disk. Sheesh!) Last I recall, yes, you could still boot from LDL just fine. It is the original layout for Linux/390 CKD. It has been bootable all along. Last time I measured DIAG -vs- SSCH, I was disappointed to not find significant performance boost with the DIAG driver. That's surprising because in theory we would get a major win when using the DIAG driver. (It is the only mode used by CMS, which gave up CCW disk I/O decades ago.) But there was no penalty, so I recommend DIAG even if throughput comparison is a wash. -- R; <>< Rick Troth Velocity Software http://www.velocitysoftware.com/ On Mon, Jan 3, 2011 at 10:59, Samir Reddahi <[email protected]>wrote: > We have currently a couple of DB2 machines with logical volumes on MOD-9 > ECKD disks. On our DB2 production server we have mdcache enabled for the > logical volumes that contains the DB2 data. The other servers have mdcache > disabled. > > We already use the DIAG driver for the swap disks and the VDISKs. Now I'm > looking if it is interesting to switch the other disks to DIAG too. > > Disks are currently formatted with cdl. I've read that cdl and DIAG can't > work together so the disks have to be formatted to another format. We will > be migrating to a new Z196 and a new DS8800, so I can use the downtime to > switch the logical volume to an LV with DIAG disks > > a couple of questions: > > 1) Are there any disadvantages of formatting disks as ldl instead of cdl? > 2) Is it true that /boot directory has to be located on a non-DIAG disk? > 3) What kind of performance improvement can I expect from a move to DIAG > dasd > 4) Any disadvantages of using DIAG instead of ECKD? > > > > Best regards > *Samir Reddahi* > > System Engineer | Systeem MF, AS400, DBA Operations > T +32 9 235 61 09 | M +32 478 80 68 30* > **[email protected]* <[email protected]> > > [image: Securex Logo]*www.securex.be* <http://www.securex.be/> > [image: Footer] > > > > - Confidentiality Notice - > > > This communication and the information it contains is intended (a) for the > person(s) or organization(s) > > named above and for no other person or organization, and (b) may be > confidential, legally privileged and > > protected by law. Unauthorized use, copying or disclosure of any of it may be > unlawful! If you receive > > this communication in error, please notify us immediately, destroy any copies > and delete it from your > computer system. Please consult our disclaimer on our site www.securex.eu > Thank you. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
