herzlich@NGP.UTEXAS.EDU (Larry Herzlich) (05/23/86)
In reply to John Bredesen's questions about the HSC50 and TA81 (May 9): >1) I have heard you can do physical disk to disk copies on the HSC, but can > you do disk to tape (and vice versa) on the HSC without a host? Yes, you can do it without the host however the disk must not be available to the cluster. >1a) If so, is the tape in backup format so it can be used by the host later > on? Yes, as indicated on a different reply, you can use the same BACKUP/PHYSICAL command and yes it is much slower than doing it on the HSC. An RA81 takes approximately 15 to 20 minutes to backup since it copies ALL logical blocks whether they are being used or not. You can improve performance by having two tape drives to eliminate rewind times. >2) What manuals are available for the HSC software v250? DEC has released a new manual available through the documentation group. It contains the much needed documentation about the Utilites which was previously documented as "Undocumented" under the V2.50 release notes. DEC Part# AA-GMEAA-TK ! approx. 300 pages As a side note to Utilities, most of the "less obvious" utilities are best left to field service since many of the prompts require that you know exactly what happens to an RA81 drive when you do things to different areas on the disk. >3) Has anyone heard of a newer version of the HSC software? Is one available > now? Is one available soon? Version 3.00 should be released any day now. (I'm holding my breath!) It's interesting to note that this will be the same release number for HSC70 owners too. It seems that DEC always starts their software levels with v1.00. Another change is that you will be receiving your "Software" (get away from the term MicroCode) through SDC so updates won't be coming through field service. See your sales rep. so they can register you as an HSC owner and also get Volume Shadowing software sent to you. Remember to buy the distribution kit and documentation even though current owners or those with HSC's on order, will receive the license free. >4) What is the performance of the TA81 tied to an HSC versus a TA81 tied > straight to the VAX? First, you must remember that the BACKUP on the HSC is different from the one under VMS. HSC BACKUP does not do ECC or XOR correction that is normally done under VMS. Second, the HSC is driving the TA81 about as fast as it can go doing seek ordering as usual and actually transferring clusters of logical blocks. Under VMS the HSC must still do it's job and talk to the CPU. Now a question to you is: Do you really want to do HSC backups? If you need your disk accessible to the cluster at ALL times then HSC backup isn't for you. If you need to store your backups for long periods of time and then hope to restore from them, then you may have problems because of media degredation and the HSC's intolerance to these errors. On the other hand, with volume shadowing in our hands (you have to pay for the Doc.), it will be easy to take one drive offline, back it up and let shadowing catch us up. With the speed of the HSC backup, the offline time is minimal. ----------------------- Now that you've read this far, I'd like to receive any mail about HSC weirdness, madness or other interesting tidbits. I gave the session on HSC Management in a VAXcluster at Dallas and will be sending my slides to the DECUS Proceedings. I need any information to update the state of the HSC from a System Manager's point of view. Sincerely, Larry Herzlich University of Texas, Computation Center Austin Texas 78712-1111 (512) 471-3241 herzlich@ut-ngp !decvax!seismo!ut-sally!ut-ngp CC.LHerzlich@a20.CC.Utexas.Edu