Re: Suggestions for drive config.?

From: Neil Hulin <nospam_at_*NOSPAM*litech.freeserve.co.uk>
Date: Wed, 2 Dec 1998 17:04:01 -0000
Message-ID: <743s07$4d2$1@newsreader3.core.theplanet.net>

Asking a question like this is like asking what options I should get with my new Chevy. I take it that you are referring to a Sun Enterprise Server and intend running Solaris.

EVERYTHING depends on:

1. Budget
2. Availability requirements
3. Performance criteria
4. Application architecture
5. Backup and Recovery requirements

EVERYTHING will be a compromise

General rules (in no particular order): 1. More small individual disks is better 2. As typical db activity is 60%-80% read and 20%-40% write

   then mirroring may provide an advantage. 3. With loads of disks, ensure that they are split across multiple SCSI i/f

   Just because you can put six drives on SCSI-II doesn't mean that

    you have to. Two or three fast disks can approach the throughput

    of SCSI-II (10Mb/s).
4. Split the mirror disks across controllers for high availability otherwise

    loosing the controller takes the db down rather than just running

    degraded.

5. You can never have enough RAM
6. Have a separate swap disk (or two, for interleaved swap)
7. Keep indexes and data tablespaces on different

disks/controllers.
8. Set the db block size no lower than the UNIX buffer cache block

    size otherwise you will be underutilising the cache. 9. Generally, faster disk rotational speed means reduced latency.
10. Disks with onboard cache MAY prove advantageous. 11. The overhead of generating recovery data on a RAID 5 device

     may result in poorer performance during write operations.
12. Mixing slow devices like tape and CD-ROM drives on the

    same SCSI as your disks may result in a performance hit.

In the above, when I refer to "disk" I mean a single physical disk, not a logical volume or filesystem.

From the hints in your question I'd probably opt for 9 x 2GB drives split across 3 SCSI controllers and use the rest of the budget on RAM. I don't know if an ES250 has this much I/O capability. If you need higher availability then duplicate the disk and controllers and implement mirroring. --
...neil {actually: neil [dot] hulin [at] litech [dot] freeserve [dot] co [dot] uk} Received on Wed Dec 02 1998 - 11:04:01 CST