Backups and optical disks

Greetings Jonathan- Hopefully, I have answered your questions. Thanks for your interest. >a. I refer to the disclaimers I put in. I concure, but it would be nice to be able to utilize some of the newer hardware. >b. I will try to get your point acknowledged by R&D Thank you. >c. I think it would still take a long time to do the backup to > an optical system, because, to the best of my knowledge, optical > systems aren't all that quick. Also, what facilities would there > be for parallel data transfers? Yes, the transfer rate is slower than disk, but faster than tape. An HP autochanger contains 32 pieces of media. All may be mounted at the same time. It has, however, only 2 drives, thus only 2 disks may be accessed at a time. >d. If the > optical device requires special controls to make it switch over to > a new platter, then it isn't all that much like a standard device > and becomes less usable. The switch to a new platter (if I understand your comment correctly) is done on the UNIX side and is transparent to the user, just like accessing a file system on a different disk. I know I keep re-emphasizing "file system" but I have not played with raw devices much and am not sure if optical disks can be used as raw devices. >f. From your signature, I take it that you work in an optical disk > part of HP. Could you give me any more details about your > system? Platter capcaity, transfer speeds, etc. Informix > normally uses raw devices, so the Unix file system facility is > probably not of interest unless it allows multi-platter files when > the raw device does not. No, I don't "work in an optical disk part of HP". I have a 20 GB optical disk autochanger that I use for database archives and backups. As for the details, I will do my best... The HP series 6300 20GB/A holds 32 pieces of magneto optical (R/W many times) media. Each piece of media holds 650 MB (unformatted) total and 325 MB (unformatted) per side. Formatted, it is reduced to 275 MB per side. Each side is considered a file system by UNIX. The disk drive is single sided, thus the media must be removed from the drive, flipped over, and re-inserted into the drive in order to access the other side. (A bit unfriendly). Data transfer rates are (copied from the accompanying manual): Reads (max sustained) 680 KB/second Writes (max sustained) 340 KB/second Burst 1.2 MB/second >Yours interestedly, >Jonathan Leffler (johnl@obelix.informix.com) #include <disclaimer.h> > -- - eko __ | | | | ___________________________________________________________ | \\ | | | \\ | Ellen K. Osinski | | | | Hewlett-Packard | \\ \\ | Boise Site Operations - Boise Surface Mount Center | / \\ | 11413 Chinden Blvd | | ---/\\ | Boise, ID 83714-1023 | | | | | | | | phone : (208) 323-4904 | | * | | e-mail: ellen@hpdmmgv.boi.hp.com | | | | telnet: 1-323-4904 | |___________| |___________________________________________________________|