Dell DSS 1510 Lifecycle Controller v2.40.40.40 Users Guide - Page 47

The number of physical disks required for the virtual disk varies depending on the RAID level. The minimum and maximum numbers of physical disks required for the RAID level are displayed on the screen. • Protocol - Select the protocol for the disk pool: Serial Attached SCSI (SAS) or Serial ATA (SATA). SAS drives are used for high performance, while SATA drives provide a more cost-effective solution. A disk pool is a logical grouping of physical disk drives on which one or more virtual drives can be created. The protocol is the type of technology used to implement RAID. • Media Type - Select the media type for the disk pool: Hard Disk Drives (HDD) or Solid State Disks (SSD). HDDs use traditional rotational magnetic media for data storage and SSDs implement flash memory for data storage. • Disk Boot Size - Select one of the following disk block sizes: - 512 - indicates that the 512 bytes block size hard drives (HDD) are selected. - 4K - indicates that the 4K block size hard disk drives (HDD) are selected. 4K block HDDs allows the faster data transfer with fewer commands. • T10 Protection Information (T10 PI) Capability- It is known as DIF (Data Integrity Fields) and the supporting HDDs are referred to DIF drives. The T10 enabled HDDs validates and stores the data integrity fields for each blocks. It performs this action when you write the data on the disk and return these values on a read request. When you read or write the data from the HDD, the data is checked for the errors. Select one of the following types of T10 protection information capabilities : - All - indicates that both the T10 PI capable and non-capable HDDs are selected. - T10 PI Capable - indicates that only T10 PI capable HDDs are selected. - Non-T10 Capable - indicates that only non-T10 capable HDDs are selected. NOTE: PERC 9 with version 9.3.2 and above doesn't support T10 PI capabilities. • Encryption Capability - Select Yes to enable encryption capability. • Select Span Length - Select the span length. The span length value refers to the number of physical disk drives included in each span. Span length applies only to RAID 10, RAID 50, and RAID 60. The Select Span Length drop‑down list is active only if you have selected RAID 10, RAID 50, or RAID 60. • Drives remaining for current span - Displays the number of physical disk-drives remaining in the current span based on the span length value selected. • Select the physical disk-drives using the check boxes at the bottom of the screen. The physical disk-drive selection must meet the requirements of the RAID level and span length. To select all the physical disk-drives, click Select All. After you select the option, the option changes to Deselect. Setting virtual disk attributes Use this page to specify the values for the following virtual drive attributes: • Size - Specify the size of the virtual drive. • Stripe Element Size - Select the stripe element size. The stripe element size is the amount of drive space a stripe consumes on each physical-disk drive in the stripe. The Stripe Element Size list may contain more options than initially displayed on the screen. Use the up arrow and down arrow keys to view all available options. • Read Policy - Select the read policy: - Read Ahead - The controller reads sequential sectors of the virtual drives when seeking data. The Read Ahead policy may improve system performance if the data is written to sequential sectors of the virtual drives. - No Read Ahead - The controller does not use the Read Ahead policy. The No Read Ahead policy may improve system performance, if the data is random and not written to sequential sectors. - Adaptive Read Ahead - The controller initiates the Read Ahead policy only if the most-recently-read requests accessed sequential sectors of the disk drive. If the most-recently-read requests access random sectors of the disk drive, then the controller uses the No Read Ahead policy. • Write Policy - Select the write policy. - Write Through - The controller sends a write-request-completion signal only after the data is written to the disk drive. The Write Through policy provides better data security than the Write Back policy, because the system assumes that the data is available only after it has been written to the disk drive. - Write Back - The controller sends a write-request completion signal as soon as the data is in the controller cache, but has not yet been written to the disk drive. The Write Back policy may provide faster 'write' performance, but it provides less data security, because a system failure can prevent the data from being written to the disk drive. 47