Linear advice saves tape storage solution
April 30, 2008
A 3000 community member who is obviously homesteading asked for help installing a Digital Linear Tape device today. His question to the HP 3000 newsgroup was "Why can't my Series 939 see the DLT8000 I just brought into the shop and mounted successfully?"
A couple of tape experts had good solutions to assist Joe Barnett, but both storage guru Denys Beauchemin and HP's Jim Hawkins couldn't resist much bigger advice: Migrate off that HP 3000. While Barnett contemplates that outsized project, he's got little to spark such an adventure — if his only problem is storing more data from a growing disk farm.
The experts shared a wide range of counsel, from the basic of "check that media" and "tape heads wear out on DLT8000s" to "they haven't made that generation of DLT drive in five years" (a period Beauchemin likes to call a lustrum, accurate but arcane English.)
When Hawkins stepped in to comment on Beauchemin's advice, the combination of counsel was another reason to believe in the power of the 3000 community.
Beauchemin, who's best known as Denys in the 3000 world, set off with an opinion, then followed with details. JIM of HP commented.
Denys: Unfortunately, this is the exact issue facing homesteaders and others who are delaying the migration off the HP3000, especially if they have pre-PCI machines. The hardware to run it can only be found in antique stores and can be of varying level of readiness. You have many options open to you, but as time goes by they will more difficult to implement.
1- Look for another DLT8000 or a DLT7000, either one will work and you will not get any performance benefit from either one over the DDS-3, just more storage on one tape.
JIM >> Agreed. Also make sure it has HP branded firmware; within the last two years had a painful set of System Aborts at a large customer due to semi-random walks through driver state machines initiated by non-certified firmware.
Denys: 2- Consider getting more DDS-3 drives.
JIM >> Agreed. We have one medium size N-Class with something like 12 DAT24 drives -- they do either a 4x3 or 3x4 parallel storeset. No messing with “reel” switches.
Denys: 3- Consider getting an HVD to SE/LVD SCSI converter and then trying a DDS-4 device.
JIM >> Don’t think that is an option since about 5.5/6.0 the “scsi_tape_dm” DDS driver will not “bind” to the F/W SCSI driver. I think you may only configure the DLT (scsi_tape2_dm) driver “under” the NIO F/W SCSI HBA (fwscsi_dam). As previously posted DAT40 with DAT24 media has worked well for some sites but DAT40 with DAT40 media is only supported on A/N-Class.
Denys: 4- Move to a PCI HP 3000 (the crippled A series or a small N-Class), then use newer LVD devices.
JIM >> Agree that PCI Systems will at least enable the usage of much newer “used” equipment and even some new stuff, if you want to buy a XP10k/12k ;-).
Denys: 5- Consider migrating from the HP 3000. (This is the only long term solution and where I have been spending my time for the last several years. The newer server technology is light-years ahead of where the 3000 stopped and the new storage devices are incredible, fast and cheap. The companies that we migrate are just amazed at the new hardware.)
JIM >> Agreed
Hardware, of course, is not the biggest challenge in migration. Moving programs, processes, training for new environments— that's where the work really begins. Besides, backing away from DLT is not all that uncommon in the 3000 community. At one point Denys told Joe about a needed interface, "HVD-SCSI is so last century." True enough. But storing to tape has its creaky looks, too. STORE To Disk is successful and better at carrying a 3000 into the next decade.