Product manual
Barracuda 18LP FC Product Manual, Rev. B 9
4.0 Performance characteristics
This section provides detailed information concerning performance-related characteristics and features of Bar-
racuda 18LP FC drives.
4.1 Internal drive characteristics
ST39175FC.............. ST318275FC
Drive capacity 9.1 ............................ 18.2..........Gbytes (formatted, rounded off value)
Read/write data heads 5 ............................... 10
Bytes per track 186,000 .................... 186,000....Bytes (average, rounded off values)
Bytes per surface 2,184 ........................ 2,184........Mbytes (unformatted, rounded off value)
Tracks per surface (total) 11,721 ...................... 11,721......Tracks (user accessible)
Tracks per inch 12,580 ...................... 12,580......TPI
Peak bits per inch 223 ........................... 223...........KBPI
Internal data rate 137-240 .................... 137-240....Mbits/sec (variable with zone)
Disc rotation speed 7,200 ........................ 7,200........rpm (+
0.5%)
Avg rotational latency 4.17 .......................... 4.17..........msec
4.2 Seek performance characteristics
See Section 9.5, “FC-AL physical interface” on page 50 and the Fibre Channel Interface Manual (part number
77767496) for additional timing details.
4.2.1 Access time
4.2.2 Format command execution time for
≥
512-byte sectors
Including controller overhead
(without disconnect)
1
,
2
(msec)
1. Execution time measured from receipt of the FCP Command to the FCP Response.
2. Assumes no errors and no sector has been relocated.
Read Write
Average Typical
3
,
4
3. Typical access times are measured under nominal conditions of temperature, voltage, and horizontal orientation as
measured on a representative sample of drives.
4. Access time = controller overhead + average seek time.
Access to data = controller overhead + average seek time + latency time.
6.9 7.8
Single track Typical
3,4
0.9 1.2
Full stroke Typical
3,4
15 16
ST39175FC ST318275FC
Maximum (with verify) 20 minutes 40 minutes
Maximum (without verify) 10 minutes 20 minutes