raw and cooked partitions on the same disk?

Posted in 2007

CONRAD DUTTON — Wed, 05 Sep 2007 13:38:43 — source: IIUG Forums & Mailing Lists

Hi, I have always managed raw devices so that they have had exclusive use of the physical drive(s). This has allowed me to monitor I/O performance of the db without interference from other processes on the storage device. I have been asked to create an application instance on an entry level Sun box without any networked storage. I only have one physical disk to play with for the application and it's data. If I go cooked I'm fairly confident I/O will bottleneck. Does anyone out there do this? Any recommendations / drawbacks / limitiations? Cheers, Conrad.

↪ replying to CONRAD DUTTON

ART KAGEL, — Wed, 05 Sep 2007 13:48:52 — source: IIUG Forums & Mailing Lists

IDS Version? Solaris Version? IDS 11.10 can use O_DIRECT for cooked devices and filesystem files on Solaris 10+. The performance of O_DIRECT on cooked (ie block) devices is very close to RAW device performance (<5% difference) with filesystem file performance about another 5% slower. If you will be using other versions of IDS and/or earlier Solaris releases that don't support O_DIRECT IO I would definitely stick to RAW (ie character) devices. I don't think it makes a difference whether there is one drive on the machine or several or it's hooked into an array or SAN, I want the fastest disk handling I can get for IDS, so my decisions are based on that premise as a starting point. Art S. Kagel ----- Original Message ----- From: Conrad Dutton <ids@iiug.org> To: ids@iiug.org At: 9/05 9:39:06 Hi, I have always managed raw devices so that they have had exclusive use of the physical drive(s). This has allowed me to monitor I/O performance of the db without interference from other processes on the storage device. I have been asked to create an application instance on an entry level Sun box without any networked storage. I only have one physical disk to play with for the application and it's data. If I go cooked I'm fairly confident I/O will bottleneck. Does anyone out there do this? Any recommendations / drawbacks / limitiations? Cheers, Conrad. ******************************************************************************* Forum Note: Use "Reply" to post a response in the discussion forum.