HFS Plus

Äëÿ òåðìèíà «HFS» ñì. äðóãèå çíà÷åíèÿ.

HFS+
Ðàçðàáîò÷èê	Apple
Ôàéëîâàÿ ñèñòåìà	Hierarchical File System Plus
Äàòà ïðåäñòàâëåíèÿ	19 ÿíâàðÿ 1998 (Mac OS 8.1)
Ìåòêà òîìà	Apple_HFS (Apple Partition Map) 0xAF (MBR) Apple_HFSX (Apple Partition Map) when HFSX 48465300-0000-11AA- AA11-00306543ECAC (GPT)
Ñòðóêòóðà
Ñîäåðæèìîå ïàïîê	B-äåðåâî
Ðàçìåùåíèå ôàéëîâ	B-äåðåâî
Ñáîéíûå ñåêòîðà	B-äåðåâî
Îãðàíè÷åíèÿ
Ìàêñèìàëüíûé ðàçìåð ôàéëà	16 EiB
Ìàêñèìóì ôàéëîâ	Íåîãðàíè÷åíî
Ìàêñèìàëüíàÿ äëèíà èìåíè ôàéëà	255 ñèìâîëîâ (255 UTF-16 encoding units, normalized to Apple-modified variant of Unicode Normalization Format D)
Ìàêñèìàëüíûé ðàçìåð òîìà	16 EiB
Äîïóñòèìûå ñèìâîëû â íàçâàíèÿõ	Unicode, ëþáûå ñèìâîëû, âêëþ÷àÿ NUL. OS API ìîæåò èñïîëüçîâàòü íåêîòîðûå ñèìâîëû äëÿ ñîâìåñòèìîñòè
Âîçìîæíîñòè
Ñâîéñòâà	access, attributes modified, backed up, contents modified, created
Äèàïàçîí äàò	1 ÿíâàðÿ 1904 - 6 ôåâðàëÿ 2040
Òî÷íîñòü õðàíåíèÿ äàòû	1ñ
Ïîòîêè ìåòàäàííûõ	Åñòü
Àòðèáóòû	Color (3 bits, all other flags 1 bit), locked, custom icon, bundle, invisible, alias, system, stationery, inited, no INIT resources, shared, desktop
Ïðàâà äîñòóïà	Unix permissions, ACLs (Mac_OS_X_Server_10.4 onward)
Ôîíîâàÿ êîìïðåññèÿ	Íåò
Ôîíîâîå øèôðîâàíèå	Íåò, íî ìîæíî èñïîëüçîâàòü òîìà .dmg, çàøèôðîâàííûå AES íà÷èíàÿ ñ Mac OS X v10.3
Ïîääåðæèâàåòñÿ ÎÑ	Mac OS 8, Mac OS 9, Mac OS X

HFS Plus èëè HFS+ èëè Mac OS Extended â ôàéëîâàÿ ñèñòåìà, ðàçðàáîòàííàÿ Apple Inc. äëÿ çàìåíû ðàíåå èñïîëüçóþùåéñÿ HFS, îñíîâíîé ôàéëîâîé ñèñòåìû íà êîìïüþòåðàõ Macintosh. Òàêæå ñ ýòîé ôàéëîâîé ñèñòåìîé ìîæåò ðàáîòàòü ïëååð iPod. HFS+ ìîæíî ðàññìàòðèâàòü, êàê óñîâåðøåíñòâîâàííóþ âåðñèþ HFS äëÿ ðàñøèðåíèÿ âîçìîæíîñòåé Mac OS. Âî âðåìÿ ðàçðàáîòêè, ýòà ñèñòåìà íàçûâàëàñü Sequoia.

HFS+ ÿâëÿåòñÿ óëó÷øåííîé âåðñèåé HFS, ñ ïîääåðæêîé ôàéëîâ áîëüøîãî ïàëëåòíîãî ðàçìåðà (32-áèòíàÿ àäðåñàöèÿ âìåñòî ñòàðîé 16-áèòíîé) è èñïîëüçóåò êîäèðîâêó Unicode äëÿ èì¸í ôàéëîâ è ïàïîê. HFS+ ïîääåðæèâàåò èìåíà äëèíîé äî 255 ñèìâîëîâ ôîðìàòà UTF-16 è ìíîãîïîòî÷íûå ôàéëû ïîäîáíî NTFS (îäíàêî ïî÷òè âñå ïðîãðàììû èñïîëüçóþò òîëüêî ïîòîê äàííûõ (àíãë. data fork) è ïîòîê ñ ðåñóðñàìè (àíãë. resource fork)). HFS+ òàêæå èñïîëüçóåò 32-áèòíóþ òàáëèöó ïðèâÿçêè ôàéëà ê ìåñòó íà äèñêå (àíãë. allocation mapping table) âìåñòî 16-áèòíîé â HFS. Ñòàðàÿ àäðåñàöèÿ ÿâëÿëàñü ñåðü¸çíûì îãðàíè÷åíèåì HFS, íå ïîçâîëÿâøèì ðàáîòàòü ñ òîìàìè îáú¸ìîì áîëåå 65 536 áëîêîâ (êàê FAT16 è FAT-32). Ïðè îáú¸ìå äèñêà â 1 ÃÁ ðàçìåð êëàñòåðà (áëîêà) ñîñòàâëÿë 16 ÊÁ â äàæå ôàéë èç 1 áàéòà çàíèìàë âñå 16 ÊÁ.

Ïîäîáíî ïðåäøåñòâåííèöå, HFS+ èñïîëüçóåò äðåâîâèäíóþ ñòðóêòóðó B*-äåðåâî äëÿ õðàíåíèÿ áîëüøåé ÷àñòè ìåòàäàííûõ.

Èñòîðèÿ

HFS+ áûëà ïðåäñòàâëåíà 19 ÿíâàðÿ 1998 ã. âìåñòå ñ Mac OS 8.1, íî âïåðâûå å¸ ïðåäñòàâèëè â êà÷åñòâå òåñòîâîé ôàéëîâîé ñèñòåìû äëÿ òàê è íå âûøåäøåé OS Copland (1994â1996 ãã.) Íà÷èíàÿ ñ 11 íîÿáðÿ 2002 ã., ñ âûïóñêîì îáíîâëåíèÿ 10.2.2, Apple Inc. ñäåëàëà âîçìîæíûì æóðíàëèðîâàíèå äëÿ ïîâûøåíèÿ íàä¸æíîñòè õðàíåíèÿ èíôîðìàöèè. Îíî áûëî ëåãêî äîñòóïíî ñ ñåðâåðíîé âåðñèåé Mac OS X, íî òîëüêî ÷åðåç èíòåðôåéñ êîìàíäíîé ñòðîêè ñ íàñòîëüíûõ êëèåíòîâ. Íà÷èíàÿ ñ Mac OS X v10.3, æóðíàëèðîâàíèå ñòàëî âêëþ÷¸ííûì ïî óìîë÷àíèþ, à òîì ñ æóðíàëîì ïîëó÷èë íàçâàíèå HFSJ.

 Mac OS 10.3 ïîÿâèëàñü ôàéëîâàÿ ñèñòåìà HFSX, ïîçâîëÿþùàÿ, â îòëè÷èå îò HFS+, ðàáîòàòü â ðåæèìå ñ ó÷¸òîì ðåãèñòðà èìåí.

Îïèñàíèå

Òîì â HFS+ ïîäåë¸í íà ñåêòîðû (â HFS íàçûâàëèñü ëîãè÷åñêèìè áëîêàìè), îáû÷íî ðàâíûå 512 áàéòàì. Îäèí èëè áîëåå ñåêòîðîâ ñîñòàâëÿþò êëàñòåð, îáùåå ÷èñëî êëàñòåðîâ çàâèñèò îò îáú¸ìà äèñêà. 32-áèòíàÿ àäðåñàöèÿ ïîçâîëÿåò ïîëó÷èòü äîñòóï ê 4 294 967 296 (2³²) êëàñòåðàì ïðîòèâ ñòàðûõ 65 536 (2¹⁶)

Îáû÷íî, òîì â HFS îáúåäèíÿåòñÿ ñ HFS Wrapper, õîòÿ ýòî ñòàíîâèòñÿ ìåíåå ðàñïðîñòðàí¸ííûì. Wrapper áûë ðàçðàáîòàí äëÿ íåñêîëüêèõ öåëåé: âî-ïåðâûõ, îí ïîçâîëÿåò Ìàêèíòîøàì áåç ïîääåðæêè HFS+ â ÏÇÓ çàãðóæàòüñÿ ñ òàêèõ òîìîâ. Âî-âòîðûõ, ýòî ïîçâîëÿåò óïðîñòèòü ïåðåõîä íà HFS+ ïóò¸ì ñîçäàíèÿ ïðîñòåéøåãî çàãðóçî÷íîãî òîìà HFS, íà êîòîðîì åñòü äîñòóïíûé òîëüêî äëÿ ÷òåíèÿ ôàéë Where_have_all_my_files_gone? (àíãë. Êóäà ïðîïàëè âñå ìîè ôàéëû?). Ôàéë ñîäåðæèò èíôîðìàöèþ äëÿ ïîëüçîâàòåëåé Mac OS áåç ïîääåðæêè HFS+, î òîì, ÷òî ýòîò ëîãè÷åñêèé äèñê òðåáóåò îïåðàöèîííóþ ñèñòåìó ñ ïîääåðæêîé HFS+. Çàãîëîâîê HFS òîìà ñîäåðæèò ñèãíàòóðó è ñìåùåíèå äî âëîæåííîãî HFS+ òîìà. Ñåêòîðû, èñïîëüçóåìûå HFS+ ïîìå÷åíû â HFS êàê äåôåêòíûå áëîêè (àíãë. bad blocks).