IBM DTLA-307075 Hard Drive Specifications - Page 27

Data transfer speed, 4.5 Buffering Operation Look ahead/Write cache, DTLA-307XXX

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4.4.4 Data transfer speed Data transfer speed Disk-Buffer transfer (Zone 0) Instantaneous - typical Sustained - typical Disk-Buffer transfer (Zone 14) Instantaneous - typical Sustained - read typical Sustained - write typical Buffer-Host (max) DTLA-305XXX (Mbyte/sec) 36.5 31.8 17.0 14.8 14.8 100 DTLA-307XXX (Mbyte/sec) 43.4 37.7 21.7 18.8 18.8 100 Figure 12. Data transfer speed Ÿ Instantaneous disk-buffer transfer rate (Mbyte/sec) is derived by the formula (Number of sectors on a track) * 512 * (revolution/sec) Note:The number of sectors per track will vary because of the linear density recording. Ÿ Sustained disk-buffer transfer rate (Mbyte/sec) is defined by considering head/cylinder change time for read operation. This gives a local average data transfer rate. It is derived by the formula (Sustained Transfer Rate) = A / (B +C +D ) where A = (Number of data sectors per cylinder) * 512 B = ((# of Surface per cylinder) - 1) * (Head switch time) C = (Cylinder change time) D = (# of Surface) * (One revolution time) Ÿ Instantaneous buffer-host transfer rate (Mbyte/sec) defines the maximum data transfer rate on the AT Bus. It also depends on the speed of the host. The method of measurement is given in 4.4.6, "Throughput" on page 0. 4.4.5 Buffering Operation (Look ahead/Write cache) To improve the total performance, the drive utilizes a ring buffer for look ahead and write cache. The total 380 KB (DTLA-305XXX) and 1916 KB (DTLA-307XXX) of the buffer is divided into multiple segmented blocks for write buffer or read buffer use. Write data will be cached in the buffer for the random block request. Deskstar 40GV & 75GXP hard disk drive specifications 15

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4.4.4 Data transfer speed
100
100
Buffer-Host (max)
18.8
14.8
Sustained - write typical
18.8
14.8
Sustained - read typical
21.7
17.0
Instantaneous - typical
Disk-Buffer transfer (Zone 14)
37.7
31.8
Sustained - typical
43.4
36.5
Instantaneous - typical
Disk-Buffer transfer (Zone 0)
DTLA-307XXX
(Mbyte/sec)
DTLA-305XXX
(Mbyte/sec)
Data transfer speed
Figure 12. Data transfer speed
°
Instantaneous disk-buffer transfer rate (Mbyte/sec) is derived by the formula
(Number of sectors on a track) * 512 * (revolution/sec)
Note:The number of sectors per track will vary because of the linear density recording.
°
Sustained disk-buffer transfer rate (Mbyte/sec) is defined by considering head/cylinder change time
for read operation. This gives a local average data transfer rate. It is derived by the formula
(Sustained Transfer Rate) = A / (B +C +D ) where
A = (Number of data sectors per cylinder)
*
512
B = ((# of Surface per cylinder) - 1)
*
(Head switch time)
C = (Cylinder change time)
D = (# of Surface)
*
(One revolution time)
°
Instantaneous buffer-host transfer rate (Mbyte/sec) defines the maximum data transfer rate on the
AT Bus. It also depends on the speed of the host.
The method of measurement is given in 4.4.6, “Throughput” on page 0.
4.4.5 Buffering Operation (Look ahead/Write cache)
To improve the total performance, the drive utilizes a ring buffer for look ahead and write cache. The total
380 KB (DTLA-305XXX) and 1916 KB (DTLA-307XXX) of the buffer is divided into multiple segmented
blocks for write buffer or read buffer use.
Write data will be cached in the buffer for the random block request.
Deskstar 40GV & 75GXP hard disk drive specifications
15