Archive for the ‘Back-of-the-Envelope’ Category
Tuesday, January 22nd, 2008
I/O stack components Overview
Typically the stack consists of the following
• Database
• Character or block device driver
• Multipathing driver
• SCSI driver
• HBA
• System Bus
• Switch/iSCSI routers
• Storage Array
• Disks
Example of vendors:
ASM-Database IBM Oracle
Character or block device driver
Multipathing driver – PowerPath, Windows MPIO
SCSI driver
HBA – Host Bus Adapter, Qlogic (IBM), Emulex
System Bus ...
Posted in hardware setup, oracle, ibm db2, Back-of-the-Envelope, Database, Storage, Design, Fibre Channel, Capacity planning | No Comments »
Tuesday, January 22nd, 2008
Don't forget to add extra IO imposed by users of the database. For example, to determine how much extra I/O will be imposed on the system when the new load is put into place. For example, if more users or reports will be added, determine how much I/O these reports ...
Posted in oracle, Back-of-the-Envelope, Storage, Design, Capacity planning | No Comments »
Tuesday, January 22nd, 2008
IO rate of 1+ Gigabytes/sec is rarely achievable, but hundreds of Megabytes/sec is achieved in lots of high-end production environment. Keep those numbers in mind when planning for what's possible.
In Oracle, use AWR reports to determine current I/O metrics (Instance Activity Stats per sec).
• IOPS = “physical reads total I/O ...
Posted in oracle, Back-of-the-Envelope, Database, Design, Capacity planning | No Comments »
Tuesday, January 22nd, 2008
Common misunderstandings:
“If I buy 2 Gigabit HBAs I will get 2 Gigabytes of throughput, that’s more than enough throughput for my 400 MB/s application”
“I only need 2 disks to store my 1 TB database, now that we have 500GB disk drives are available!”
The first misunderstanding is not just about bits ...
Posted in Back-of-the-Envelope, Database, Storage, Design, Fibre Channel, Capacity planning | No Comments »
Tuesday, January 22nd, 2008
IOPS
• The standard unit of measurement for I/O operations per second.
Includes all reads and writes.
• This is how you rate a I/O stack components ability to process small
block random I/O requests.
• Used to describe I/O rate driven applications (OLTP, random I/O )
Mbytes/s
• Mega”Bytes” per sec
• Used to measure large block ...
Posted in oracle, Back-of-the-Envelope, Database, Storage, Design | No Comments »
Tuesday, January 22nd, 2008
Saw this definition from one of the Oracle OpenWorld sessions, thought it was pretty clear and concise:
Throughput
The measure of the transfer of bits across the media over a given period of time. Commonly used in discussing data transfer rates
Due to a number of factors, throughput usually does not match the ...
Posted in Back-of-the-Envelope, Database, Storage, Design, Fibre Channel | No Comments »