Linux and large HD

Hi, I have a 32 GB hard disk running in a Linux box that I want to install Informix on. (It is actually multiple disks but the RAID controller makes them look like one to the OS.) The manual says that a chunk can be no larger than 2 GB. Linux only supports 16 partitions, and my first data partition has to be #6, so I get only {6,...,16} * 2 = 22 GB of usable space if I have one chunk per partition (or is there something wrong with that reasoning?). Now, the manual also says that a chunk can have an offset of up to 2 GB into the partition. That would save me because I could create 4 GB partitions and have two 2 GB chunks on each, one with offset 0, one with offset 2 GB. I hesitate, though, because this 2 GB limit smells like somebody using seek() to position within the chunk, and that would mean that (offset+partitionSize)<2GB, NOT (as the admin guide says) offset <2GB and partitionSize <2GB. Any enlightenment on that? Thanks Frederik -- Frederik Ramm (frederik@remote.org)

In article <7re5qr$o7$1@guanaco.rhein-main.de>, frederik@remote.org (Frederik Ramm) wrote: > Hi, > > I have a 32 GB hard disk running in a Linux box that I want to > install Informix on. (It is actually multiple disks but the RAID > controller makes them look like one to the OS.) > > The manual says that a chunk can be no larger than 2 GB. Linux > only supports 16 partitions, and my first data partition has to > be #6, so I get only {6,...,16} * 2 = 22 GB of usable space if > I have one chunk per partition (or is there something wrong with > that reasoning?). > > Now, the manual also says that a chunk can have an offset of up > to 2 GB into the partition. That would save me because I could > create 4 GB partitions and have two 2 GB chunks on each, one > with offset 0, one with offset 2 GB. > > I hesitate, though, because this 2 GB limit smells like somebody > using seek() to position within the chunk, and that would mean > that (offset+partitionSize)<2GB, NOT (as the admin guide says) > offset <2GB and partitionSize <2GB. > > Any enlightenment on that? > > Thanks > Frederik > > -- > Frederik Ramm (frederik@remote.org) > This is true the limit 2G limitation that I have been told is due to the use of the seek() system call. As you have already suspected the limitation does apply to offset+partition size therefore, the maximum size of any chunk is limited to 2G no matter how much you offset into it. If you were to create a 4G chunk the last 2G would be unusable. One more thing however, I have heard that someone is working on a Logical Volume manager for Linux, if this is true surely it would overcome the limitation in Linux for number of partitions. I found some info at http://linux.msede.com/lvm/ Sent via Deja.com http://www.deja.com/ Share what you know. Learn what you don't.

Your nose is correct. It is offset+chunk size < 2GB (speaking from experience under Solaris)... You have to partition the disk into 2GB pieces so that offset+chunk size will never exceed 2 GB. Frederik Ramm <frederik@remote.org> wrote in message news:7re5qr$o7$1@guanaco.rhein-main.de... > Hi, > > I have a 32 GB hard disk running in a Linux box that I want to > install Informix on. (It is actually multiple disks but the RAID > controller makes them look like one to the OS.) > > The manual says that a chunk can be no larger than 2 GB. Linux > only supports 16 partitions, and my first data partition has to > be #6, so I get only {6,...,16} * 2 = 22 GB of usable space if > I have one chunk per partition (or is there something wrong with > that reasoning?). > > Now, the manual also says that a chunk can have an offset of up > to 2 GB into the partition. That would save me because I could > create 4 GB partitions and have two 2 GB chunks on each, one > with offset 0, one with offset 2 GB. > > I hesitate, though, because this 2 GB limit smells like somebody > using seek() to position within the chunk, and that would mean > that (offset+partitionSize)<2GB, NOT (as the admin guide says) > offset <2GB and partitionSize <2GB. > > Any enlightenment on that? > > Thanks > Frederik > > -- > Frederik Ramm (frederik@remote.org)

Size + Offset < 2G. It's a built in limitation on how Informix was written. But, how about making one or more e2fs partitions and create dbspaces that are files in those areas. You'll loose some performance in those dbspaces, so I'd put low priority/low access data there. If you configure informix with enough buffer cache you may not even notice a performance difference. S.W. Frederik Ramm <frederik@remote.org> wrote in message news:7re5qr$o7$1@guanaco.rhein-main.de... > Hi, > > I have a 32 GB hard disk running in a Linux box that I want to > install Informix on. (It is actually multiple disks but the RAID > controller makes them look like one to the OS.) > > The manual says that a chunk can be no larger than 2 GB. Linux > only supports 16 partitions, and my first data partition has to > be #6, so I get only {6,...,16} * 2 = 22 GB of usable space if > I have one chunk per partition (or is there something wrong with > that reasoning?). > > Now, the manual also says that a chunk can have an offset of up > to 2 GB into the partition. That would save me because I could > create 4 GB partitions and have two 2 GB chunks on each, one > with offset 0, one with offset 2 GB. > > I hesitate, though, because this 2 GB limit smells like somebody > using seek() to position within the chunk, and that would mean > that (offset+partitionSize)<2GB, NOT (as the admin guide says) > offset <2GB and partitionSize <2GB. > > Any enlightenment on that? > > Thanks > Frederik > > -- > Frederik Ramm (frederik@remote.org)