Chapter 8: Technology Background
259
Choosing Stripe Size
Stripe Size, also called “Stripe Block Size”, refers to the size of the data blocks
written to, and read from, the physical drives. Stripe Size is specified when you
create a disk array. In order to change the Stripe Size of an existing disk array,
you must delete the disk array and create a new one. You can choose Stripe Size
directly when you use the Advanced function to create a disk array. If you use the
Express function to create a disk array, WebPAM PRO selects the Stripe Size
when you choose an Application Type.
The available Stripe Sizes are 64, 128, 256 KB, 512 KB, and 1 MB. 64 KB is the
default. There are two issues to consider when selecting the Stripe Size.
First, you should choose a Stripe Size equal to, or smaller than, the smallest
cache buffer found on any physical drive in the disk array. Selecting a larger
value slows read/write performance because physical drives with smaller cache
buffers need more time for multiple accesses to fill their buffers.
Second, if your data retrieval consists of fixed data blocks, such as with some
database or video applications, then you should choose that size as your Stripe
Size.
If you do not know the cache buffer or fixed data block sizes, Promise suggests
you choose 64 KB as your Stripe Size. Generally speaking, email, POS, and Web
Servers prefer smaller stripe sizes. Video and database applications prefer larger
stripe sizes.
Choosing Sector Size
A sector is the smallest addressable area on a physical disk drive. Sector Size
refers to the size of sector measured by the number of bytes of data it can hold.
The most common sector size is 512 bytes (512 B). A smaller sector size results
in a more efficient use of a disk drive’s capacity. 512 B is the default sector size
for logical drives on VessRAID.
The number of usable sectors is limited by the addressing method of the
computer's operating system:
•
Windows 2000 and Windows XP (32-bit) support 10-bit logical bit addressing
(LBA), so with 512 B sectors, they can only support up to 2 terabytes (TB) of
data storage capacity. To increase the capacity, you must use larger sectors.
See “2 TB Limitation” on page 260.
•
Windows XP (64-bit), Windows 2003 Server, Windows 2008 Server, and
Windows Vista support 64-bit LBA, so they are not affected by this limitation.
For these OSes, always choose the default 512 B sector size.
•
Linux operating systems with the 2.4 kernel do not support variable sector
sizes. For these OSes, always choose the default 512 B sector size.
Summary of Contents for VessRAID 1720i
Page 1: ...VessRAID 1720i 1730i 1740i 1820i 1830i 1840i Product Manual Version 1 1 ...
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Page 114: ...VessRAID 1000i Series Product Manual 98 The changes take effect immediately ...
Page 126: ...VessRAID 1000i Series Product Manual 110 Figure 8 Disk Status LED Disk Status ...
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Page 165: ...Chapter 5 Management with the CLU 149 Figure 4 Controller Status LED Controller Status ...
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