Вообще-то, для Informix лучше использовать raw-device .... и не только под SUN ... :)

Ответ Art.Kagel:
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OK reading the White Paper (the 3rd link below) several things are clear:

- JFS2 is a fairly light weight journaled filesystem since it only journals meta-data
- It would appear that it is safe to use (unlike EXT4 and EXT3 with write-back enabled).
- If you use JFS2 for IDS chunks you must either create the filesystem with 2K alignment or 4K alignment.  If you use 4K alignment you must not use dbspace pagesizes that are not multiples of 4K.
- You must mount the FS (or at least the directory containing the chunk files) with Concurrent IO (CIO) enabled in order to get decent performance compared to RAW.
- IBM's own testing using Oracle for OLTP benchmark loads shows that using JFS2 with CIO enabled and FS alignment correct is about 8% slower than using RAW chunks and that just using Direct IO (DIO) with proper FS alignment is as much as 70% slower than RAW which is MUCH worse than the 25-40% I have tested over the years with traditional non-jounaled filesystems.

From the second White Paper which tests CIO and DIO using DB2 UDB we learn:

- Using Direct IO (DIO) on JFS2 is only efficient if the filesystem is NOT enabled for large files.  So here we are back to 2GB or smaller chunks.
- CIO on large file enabled FSs is OK.
- The test was IO bound as the disk farm had insufficient bandwidth to satisfy the tests IO demands.
- Here CIO comes much closer to RAW but IB that's only because the test was IO bound.

Personally I am going to continue to recommend that we avoid all journaled file systems forchunks.  I still think that RAW is the best way to go and that if one must use a filesystem it should be the simplest filesystem available that supports DIO.
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Интересный материал на данную тему:
http://www.ibm.com/developerworks/library/l-journaling-filesystems/index.html

Improving Database Performance With AIX Concurrent I/O
https://www-03.ibm.com/systems/resources/systems_p_os_aix_whitepapers_db_perf_aix.pdf

As for benchmarking, there is an IBM document about CIO/DIO etc.:
http://www.ibm.com/developerworks/data/library/techarticle/dm-0408lee/

And another one:
https://www-03.ibm.com/systems/resources/systems_p_os_aix_whitepapers_db_perf_aix.pdf
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С уважением,
Вадим.