Re: Disk Layout and mirroring in 7.x

On Wed, 07 Jan 1998 22:59:20 -0500, "Accent Software, Inc." <accent@accentsoftware.com> wrote: >Erik A. Widholm wrote: >> >> We are currently installing a new 4-way K570 (HP) and will be moving our >> database to it. My question is about mirroring: >> >> I have 5 Fast/Wide SCSI channels, 1 w/ 16GB (4 drives) and 4 w/ 32GB (8 >> drives). Our database currently takes about 14 GB. With the OS (HP-UX >> 10.20 using NFS), what is the recommended way to first separate the >> database and OS (minimum of 9 dbspaces, 3 of which are hugely used) over >> the chanels? >> >> Also, and more importantly: is it better to use the OS's disk mirroring >> or Informix's own? > >If your platform supports hardware SCSI read/writes across >the controllers, there's no comparison between Informix's >mirroring and hardware mirroring. Hardware mirroring will >be your best bet. > >One advantage I can think of using Informix mirroring in this >case is the split reads across the mirrored disks, increasing >the parallelism. You be the judge of the trade-off. But keep >in mind Informix mirroring was not designed to be a substitute >for hardware mirroring, but as a method when the hardware does >not support mirroring. > >Good luck, >Arun Just for assorted giggles, have you (Erik) looked at some of HP's RAID offerings? I'd suspect Mirror/UX (OS mirroring software) to be roughly comparable to Informix mirroring. I've got a Model 20 array (relabeled Data General Clariion) here that I'm going to be loading up around 10 gigabytes, on 2 F/W differential channels. You may also want to consider the HP AutoRAID box, but I don't have any direct knowledge of that beast. One of the downsides I've discovered with Informix is the inability to use a volume past the 2 gigabyte mark. Fortunately, I should be able to use the 2 gb modules for most of this. If I were using 4 gb disks, I'd have to use LVM to allow Informix to access the entire disk, instead of half. I'd like to get around this restriction, but I haven't figured it out yet. Jeff Kalchik ---------------------------------------- Views expressed are my own, not necessarily 3COM's.