Internal Disk Options - IBM Power System E850C Technical Overview And Introduction

Each Easy Tier array is made up of two individual arrays of the same type, one populated with
HDDs and one with SSDs. So a RAID 5T2 Array is formed of a RAID 5 array of HDDs and a
RAID 5 array of SSDs. As such, the following minimum device quantities required:
RAID 5T2 requires at least three HDDs and three SSDs
RAID 6T2 requires at least four HDDs and four SSDs
RAID 10T2 requires at least two HDDs and two SSDs
The HDD and SSD can be different capacities in an Easy Tier array. However, if either half of
the array has multiple capacity points, the used capacity might be lower. For example, with a
mix of 300 GB HDDs and 600 GB HDDs, only 300 GB of the larger 600 GB HDDs are used.
Similarly, if an array has both 387 GB SSDs and 775 GB SSDs, only 387 GB of the 775 GB
SSDs are used. A combination of 600 GB HDDs and 387 GB SSDs allows you to use the full
capacity of all devices.
Note: The block size of the drives in an array must match, covering both HDDs and SSDs.
So either all drives must be formatted with a 4 k block size, or all must be formatted with a
5 xx block size.

2.10.5 Internal disk options

Each of the controller options that are available provides a backplane with eight SFF-3 disk
bays in the server. These 2.5-inch (SFF) SAS bays can support both HDDs and SSDs
mounted in a Gen3 carrier. Previous generation SFF disk types (SFF-1 and SFF-2) do not fit
in these bays. All SFF-3 bays support concurrent maintenance or hot-plug capability. All three
of the controller options support HDDs or SSDs or a mixture of HDDs and SSDs in the SFF-3
bays. If you mix HDDs and SSDs, they must be in separate arrays (unless using the Easy Tier
function).
The storage backplane also has four 1.8-inch storage bays. These bays can hold
1.8-inch SSDs to provide high-performance storage for Easy Tier arrays.
Table 2-26 lists the drives that are available for the internal bays of the Power E850C server.
Table 2-26 Drives available for internal storage bays on the Power E850C
Feature Code
ES0L
ES0N
ES0U
ES0W
ES16
ES1C
ES2V
ES2X
ES4K
ES7K
ES7P
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IBM Power System E850C: Technical Overview and Introduction
Capacity Type
387 GB SSD
775 GB SSD
387 GB 4k block SSD
775 GB 4k block SSD
387 GB SSD
387 GB 5xx SSD eMLC4
387 GB 4k SSD eMLC4
775 GB 5xx SSD eMLC4
775 GB 4k SSD eMLC4
387 GB SSD 5xx eMLC4
775 GB SSD 5xx eMLC4
Placement
SSF-3 bay
SSF-3 bay
SFF-3 bay
SFF-3 bay
1.8-inch bay
1.8-inch bay
1.8-inch bay
1.8-inch bay
1.8-inch bay
SFF-3 bay
SFF-3 bay