Fea tu re D es cri pt io ns
Maxtor Atlas 10K III 6-9
If the block's data is unrecover abl e, the block may or may not be replaced acc ording
to t he st a te of t he R UEE bit i n t he Maxt or V endor Unique Pa ge. If the RUEE bi t is
set, the bad data is relocated with a Bad Data Mark appended to it. If the PER bit is
set in the Read-Writ e R ecovery Pa g e, operations r esul t ing in bad bl ock r epl acement
activate Check
SCAM is a process of automa tic ID assignment tha t eliminates the need for user
involvement in the setting of unique SCSI I Ds. The drives support and conform to
the SCAM-2 automatic ID assignment protocol cont ai ned in the SCSI-3 draft
standar ds for SCAM . T he drives are also fully com p atible w ith SCS I devices that do
not com ply with SCAM requirements.
SCSI-3 provides incr eas ed performanc e and ver satility t o SCSI di sks. LVD uses lower
level voltage swings, d ifferen tial signaling, and double transition (DT) clock ing to
allow a maximum bus speed of 160 or 320 MB/second in wide SCSI configurations.
The Maxtor Atlas 10K III disk drive supports the LVD/MSE (Multi-Mode LVD and
Single-Ended) interface standard. When in stalled on a bu s with only LVD d ev ices the
Maxtor A tlas 10 K III dis k driv e o p e rat e s in LVD mo d e at transf e r rates up to 160 or
320 MB/sec ond. It is fully compatible w ith Ultra2 LVD dev ices op erating at slower
tran sfer rates. If an Ma xto r A t las 1 0K III di sk dr ive is inst alle d on a b us w ith one or
more single-ended (SE) devices, it automatically switches modes to operate in SE
mode at the slower, legacy data rates.
Differential SCSI operation has the advantage of higher reliabilit y of data transfer
through inc reas ed immunity to electr ical nois e. Diffe rential sig naling uses a two-wi re
active system in which current from each wire flows in opposite directions and
reverses direction for a signal transition. The direction of current flow determines
whether the voltage levels on the t wo wires have a hi gh/low or low/high relationship
to each other. The common mode, or reference, level for the two LVD signals is
+1.25 vo lts. High and low is defined relative to this level. LVD permits a wide range
of signal amplitudes. The Maxtor Atlas 10K III interface drivers are designed to
provide a high to low range on each signal of approximately 400 millivolts in a
nominal configuration, resulting in a differential signal of approximately 800
m illivolts.
Single-ended SCSI, in contrast, uses one-wire active signaling with the signal return
wire connected to ground. The act i ve si g na l r an ge is switche d between a hig h i n t he
r an ge o f +2.4 - 3. 0 v o lts and a low in t he range of 0 - +. 5 v o l ts. LVD/MS E SCSI
devices in sin gle- ende d mode do not have the sig na l retur n wir es connec ted dir e ct ly
to ground, as these same pins must be driven to LVD levels when the device is
operating in LVD mode. Instead, when in single-ended mode, the device turns on a
driver transistor for each return line that acts as a switch to connect the signal return
to ground.