User Manual

SCSI Commands Reference Manual, Rev. J 391
www.seagate.com Parameters for direct access devices
5.3.9 Caching Mode page (08h)
The Caching Mode page for MODE SENSE/MODE SELECT defines the parameters that affect the use of the cache (see table 372).
PS bit
The returned Parameter Savable (PS) bit of 1 indicates that page 08h parameter data is savable.
SPF bit, the PAGE CODE field and the PAGE LENGTH field
The SPF bit, the PAGE CODE field and the PAGE LENGTH field shall be set to the values shown in table 372 for the Caching mode page.
IC enable bit
1 When the Initiator Control (IC) enable bit is set to one, adaptive read look-ahead (ARLA) is disabled.
0 When IC is set to ZERO, ARLA is enabled. Since Seagate drives covered by this manual do not organize the cache according to size of seg-
ment, but rather by number of segments, this bit is used to enable or disable ARLA (in non-Seagate equipment, this might be used to
designate cache size).
Note. ARLA cannot be disabled in some Seagate drives using the ASAII code. See individual drive’s Product Manual, Volume 1.
ABPF bit
1 The ABORT PREFETCH (ABPF) bit, when set to one, with the DRA bit equal to zero, requests that the SCSI device abort the PREFETCH
upon selection. The ABPF set to one takes precedence over the Minimum PREFETCH bytes.
0 When set to zero, with the DRA bit equal to zero, the termination of any active PREFETCH is dependent upon Caching Page bytes 4
through 11 and is operation and/or vendor-specific.
Table 372 Caching Mode page (08h)
Bit
Byte
7 6 5 4 3 2 1 0
0 PS SPF (0b) PAGE CODE (08h)
1 PAGE LENGTH (12h)
2 IC ABPF CAP DISC SIZE WCE MF RCD
3 DEMAND READ RETENTION PRIORITY WRITE RETENTION PRIORITY
4 (MSB)
DISABLE PREFETCH TRANSFER LENGTH
5 (LSB)
6 (MSB)
MINIMUM PREFETCH
7 (LSB)
8 (MSB)
MAXIMUM PREFETCH
9 (LSB)
10 (MSB)
MAXIMUM PREFETCH CEILING
11 (LSB)
12 FSW LBCSS DRA Vendor specific SYNC_PROG NV_DIS
13 NUMBER OF CACHE SEGMENTS
14 (MSB)
CACHE SEGMENT SIZE
15 (LSB)
16 Reserved
17 (MSB)
Obsolete . . .
19 (LSB)