Can Raw and Cooked Devices work well on same DBSPACE?

I have a question regarding raw and cooked devices: I had a short term contract with a company in the Chicago area. (Not related to performance improvement, although I noticed performance problems so I did a little poking around). Environment: Aix 4.3.3 Informix 7.31.uc5 EMC Symmetrix (vsn unknown). Several of the dbspaces were comprised of combinations of raw and cooked devices. Example dbspace1 has three chunks linked to the following devices. (Each at least 20 gigabytes). brw-rw--- /dev/raw_informix00 crw-rw--- /dev/informix01 brw-rw--- /dev/raw_informix02 onstat -g iov showed what I believed to be too many aio calls (ascompared with kio calls). Until this contract, it had been over 2 years since I had touched Informix. My recollections is that combining dbspace chunks in such a manner, while it may work, would cause strange IO results. I also noticed via IOSTAT that, from time to time, the symmetrix power disks seemed to lock, showing 100% active. Anybody have any more thoughts on this? Even though the contract is over, I would like to verify this and let the company DBA know about it. Thanks in advance. Ted

<twhitti615@yahoo.com> wrote in message news:fuv2i1h3ir9m1aj0ps45kb20fs295iefg1@4ax.com... > I have a question regarding raw and cooked devices: > > I had a short term contract with a company in the Chicago area. (Not > related to performance improvement, although I noticed performance > problems so I did a little poking around). > > Environment: > > Aix 4.3.3 > Informix 7.31.uc5 > EMC Symmetrix (vsn unknown). > > Several of the dbspaces were comprised of combinations of raw and > cooked devices. Example > > dbspace1 has three chunks linked to the following devices. (Each at > least 20 gigabytes). > > brw-rw--- /dev/raw_informix00 > crw-rw--- /dev/informix01 > brw-rw--- /dev/raw_informix02 > > > onstat -g iov showed what I believed to be too many aio calls (as> compared with kio calls). > > Until this contract, it had been over 2 years since I had touched > Informix. My recollections is that combining dbspace chunks in such a > manner, while it may work, would cause strange IO results. > > I also noticed via IOSTAT that, from time to time, the symmetrix power > disks seemed to lock, showing 100% active. > > Anybody have any more thoughts on this? Even though the contract is > over, I would like to verify this and let the company DBA know about > it. > > Thanks in advance. > Ted It seems that block devices (buffered by operating system) instead of character devices have been used (brw-rw-rw), probably due to a mistake when creating the chunk. The naming convention messed up seems to indicate that too. By the way, 7.31 has a 2 Gb limit, how can Informix use the remaining 18 Gb? In general, a mix of raw device chunks and cooked files is possible, because each chunk is distinct, but not advisable.