{"id":6473,"date":"2020-08-25T00:50:10","date_gmt":"2020-08-25T00:50:10","guid":{"rendered":"https:\/\/www.thegioimaychu.vn\/blog\/?p=6473"},"modified":"2020-08-25T02:24:46","modified_gmt":"2020-08-25T02:24:46","slug":"tim-hieu-su-khac-biet-giua-cac-cong-nghe-luu-tru-multi-layer-ssd-slc-mlc-tlc-qlc-va-plc","status":"publish","type":"post","link":"https:\/\/thegioimaychu.vn\/blog\/tong-hop\/tim-hieu-su-khac-biet-giua-cac-cong-nghe-luu-tru-multi-layer-ssd-slc-mlc-tlc-qlc-va-plc-p6473\/","title":{"rendered":"T\u00ecm hi\u1ec3u s\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa c\u00e1c c\u00f4ng ngh\u1ec7 l\u01b0u tr\u1eef multi-layer SSD: SLC, MLC, TLC, QLC v\u00e0 PLC"},"content":{"rendered":"<style>.iblink{color:#975!important;}.iblink:hover{color:orange!important;}<\/style><p>C\u00f9ng t\u00ecm hi\u1ec3u s\u1ef1 kh\u00e1c bi\u1ec7t quan tr\u1ecdng v\u1ec1 dung l\u01b0\u1ee3ng, hi\u1ec7u su\u1ea5t v\u00e0 \u0111\u1ed9 tin c\u1eady gi\u1eefa c\u00e1c c\u00f4ng ngh\u1ec7 l\u01b0u tr\u1eef \u0111a l\u1edbp multi-layer SSD \/ flash storage khi trang b\u1ecb <a class=\"iblink\" href=\"\/linh-kien-may-chu\/ssd\/\">\u1ed5 c\u1ee9ng SSD<\/a> v\u00e0o h\u1ec7 th\u1ed1ng c\u1ee7a c\u1ee7a b\u1ea1n.<\/p>\n<p>C\u00e1c <a class=\"iblink\" href=\"\/linh-kien-may-chu\/ssd\/\">\u1ed5 c\u1ee9ng SSD<\/a>, hay c\u00f2n g\u1ecdi l\u00e0 NAND flash, hi\u1ec7n v\u1eabn \u0111ang l\u00e0 m\u1ed9t ch\u1ee7 \u0111\u1ec1 n\u00f3ng \u0111\u1ed1i v\u1edbi c\u00e1c chuy\u00ean gia CNTT. Ch\u00fang \u0111\u01b0\u1ee3c trang b\u1ecb trong c\u00e1c flash-array, thi\u1ebft b\u1ecb NAS, \u1ed5 c\u1ee9ng chu\u1ea9n 2.5in truy\u1ec1n th\u1ed1ng v\u00e0 PCIe memory card. Flash SSD \u0111\u00e3 nhanh ch\u00f3ng tr\u1edf th\u00e0nh nh\u00e2n t\u1ed1 quan tr\u1ecdng \u0111\u1ec3 b\u00e0n lu\u1eadn trong vi\u1ec7c n\u00e2ng c\u1ea5p dung l\u01b0\u1ee3ng l\u01b0u tr\u1eef, nh\u01b0ng vi\u1ec7c \u0111\u01b0a ra c\u00e1c quy\u1ebft \u0111\u1ecbnh mua s\u1eafm c\u00f3 th\u1ec3 g\u1eb7p kh\u00f3 kh\u0103n n\u1ebfu ch\u01b0a hi\u1ec3u h\u1ebft c\u00e1c c\u00f4ng ngh\u1ec7 b\u00ean trong.<\/p>\n<p>C\u00f3 nh\u1eefng l\u00fd do r\u1ea5t thuy\u1ebft ph\u1ee5c cho vi\u1ec7c c\u00e1c \u1ed5 SSD flash gi\u1eefa c\u00e1c c\u00f4ng ngh\u1ec7 nh\u01b0 Single-level Cell (SLC), Multi-level Cell (MLC), Trible-level Cell (TLC), Quad-level Cell (QLC) v\u00e0 th\u1eadm ch\u00ed l\u00e0 PLC (penta-level cell), bao g\u1ed3m v\u1ea5n \u0111\u1ec1 hi\u1ec7u su\u1ea5t, hi\u1ec7u qu\u1ea3 s\u1eed d\u1ee5ng \u0111i\u1ec7n, t\u00ednh kh\u1ea3 d\u1ee5ng v\u00e0 \u0111\u1ed9 tin c\u1eady.<\/p>\n<p>C\u00f3 m\u1ed9t \u0111i\u1ec3m b\u1ea5t l\u1ee3i \u1edf \u1ed5 SSD flash l\u00e0 ch\u00fang v\u1eabn c\u00f2n \u0111\u1eaft h\u01a1n <a class=\"iblink\" href=\"\/linh-kien-may-chu\/hdd\/\">\u1ed5 c\u1ee9ng HDD<\/a> khi \u0111\u01b0\u1ee3c t\u00ednh tr\u00ean c\u01a1 s\u1edf gi\u00e1 ti\u1ec1n tr\u00ean m\u1ed7i gigabyte. Ch\u00fang th\u01b0\u1eddng s\u1ebd kh\u00f4ng \u0111\u1eaft n\u1ebfu \u0111\u01b0\u1ee3c \u0111o l\u01b0\u1eddng d\u01b0\u1edbi d\u1ea1ng th\u00f4ng l\u01b0\u1ee3ng nh\u01b0 USD\/1GB throughput ho\u1eb7c USD\/IOPS. Nh\u01b0ng dung l\u01b0\u1ee3ng v\u1eabn l\u00e0 ti\u00eau ch\u00ed, l\u00e0 &#8220;c\u00e2y \u0111inh&#8221; ch\u1ee7 ch\u1ed1t trong l\u0129nh v\u1ef1c l\u01b0u tr\u1eef CNTT. Vi\u1ec7c s\u1ea3n sinh v\u00e0 thu th\u1eadp d\u1eef li\u1ec7u \u0111ang tr\u00ean \u0111\u01b0\u1eddng cong gia t\u0103ng theo c\u1ea5p s\u1ed1 nh\u00e2n, t\u1eeb IoT, 5G v\u00e0 AI-machine learning. N\u0103ng l\u1ef1c l\u1ef1c l\u01b0u tr\u1eef l\u00e0 m\u1ed9t ti\u00eau ch\u00ed ch\u00ednh.<\/p>\n<h3>Chi ph\u00ed so v\u1edbi c\u00f4ng su\u1ea5t<\/h3>\n<p>C\u00e2u tr\u1ea3 l\u1eddi c\u1ee7a ng\u00e0nh l\u01b0u tr\u1eef flash cho c\u00e1c v\u1ea5n \u0111\u1ec1 v\u1ec1 chi ph\u00ed v\u00e0 dung l\u01b0\u1ee3ng c\u1ee7a SSD flash \u0111\u00e3 \u0111i theo hai h\u01b0\u1edbng m\u00e0 kh\u00f4ng lo\u1ea1i tr\u1eeb l\u1eabn nhau. \u0110\u1ea7u ti\u00ean l\u00e0 th\u00eam s\u1ed1 bit tr\u00ean m\u1ed7i cell, hay c\u00f2n g\u1ecdi l\u00e0 \u00f4 nh\u1edb. M\u1ed7i \u00f4 ch\u1ea5p nh\u1eadn m\u1ed9t s\u1ed1 bit nh\u1ea5t \u0111\u1ecbnh. M\u1ed7i bit \u0111\u01b0\u1ee3c \u0111\u0103ng k\u00fd l\u00e0 1 ho\u1eb7c 0. M\u1ed7i bit \u0111\u01b0\u1ee3c th\u00eam v\u00e0o \u00f4 s\u1ebd l\u00e0m t\u0103ng dung l\u01b0\u1ee3ng \u00f4 theo c\u1ea5p s\u1ed1 nh\u00e2n b\u1eb1ng c\u00e1ch t\u0103ng s\u1ed1 tr\u1ea1ng th\u00e1i m\u00e0 m\u1ed9t \u00f4 c\u00f3 th\u1ec3 c\u00f3 2<sup>n<\/sup>\u00a0trong \u0111\u00f3 &#8220;n&#8221; l\u00e0 s\u1ed1 bit trong m\u1ed9t \u00f4. SLC l\u00e0 2<sup>1<\/sup>\u00a0ho\u1eb7c 2 tr\u1ea1ng th\u00e1i; MLC l\u00e0 2<sup>2<\/sup>\u00a0ho\u1eb7c 4 tr\u1ea1ng th\u00e1i; TLC l\u00e0 2<sup>3<\/sup> ho\u1eb7c 8 tr\u1ea1ng th\u00e1i; QLC l\u00e0\u00a02<sup>4<\/sup> ho\u1eb7c 16 tr\u1ea1ng th\u00e1i; v\u00e0 PLC l\u00e0 2<sup>5<\/sup> ho\u1eb7c 32 tr\u1ea1ng th\u00e1i. C\u00f9ng m\u1ed9t k\u00edch th\u01b0\u1edbc t\u1ea5m wafer t\u1ea1o ra m\u1eadt \u0111\u1ed9 g\u1ea5p \u0111\u00f4i so v\u1edbi bits\/cell tr\u01b0\u1edbc \u0111\u00e2y. \u0110i\u1ec1u \u0111\u00f3 l\u00e0m t\u0103ng dung l\u01b0\u1ee3ng trong khi gi\u1ea3m chi ph\u00ed cho m\u1ed7i gigabyte.<\/p>\n<p>Con \u0111\u01b0\u1eddng t\u0103ng dung l\u01b0\u1ee3ng th\u1ee9 hai l\u00e0 chuy\u1ec3n t\u1eeb c\u00f4ng ngh\u1ec7 ph\u1eb3ng hay 2D sang 3D. C\u00f4ng ngh\u1ec7 3D cho ph\u00e9p c\u00e1c \u00f4 NAND \u0111\u01b0\u1ee3c x\u1ebfp th\u00e0nh t\u1eebng l\u1edbp. Ph\u1ea3i m\u1ea5t m\u1ed9t th\u1eddi gian \u0111\u1ec3 c\u00e1c nh\u00e0 s\u1ea3n xu\u1ea5t NAND th\u00e0nh th\u1ea1o vi\u1ec7c ph\u00e2n l\u1edbp 3D; gi\u1edd \u0111\u00e2y h\u1ecd c\u00f3 th\u1ec3 cung c\u1ea5p chip 3D NAND Flash th\u01b0\u1eddng c\u00f3 96 l\u1edbp tr\u1edf l\u00ean. C\u00f4ng ngh\u1ec7 3D gi\u00fap t\u0103ng \u0111\u00e1ng k\u1ec3 dung l\u01b0\u1ee3ng SSD flash trong khi l\u1ea1i gi\u1ea3m chi ph\u00ed cho m\u1ed7i GB. \u0110i\u1ec1u quan tr\u1ecdng c\u1ea7n l\u01b0u \u00fd l\u00e0 hi\u1ec7n t\u1ea1i v\u1eabn ch\u01b0a c\u00f3 chip 3D SLC.<\/p>\n<p>Nhi\u1ec1u bit h\u01a1n tr\u00ean m\u1ed7i \u00f4 v\u00e0 nhi\u1ec1u l\u1edbp h\u01a1n tr\u00ean m\u1ed7i chip gi\u00fap t\u0103ng dung l\u01b0\u1ee3ng flash SSD \u0111\u1ed3ng th\u1eddi gi\u1ea3m chi ph\u00ed tr\u00ean m\u1ed7i GB. Tin t\u1ed1t l\u00e0 m\u1eadt \u0111\u1ed9 dung l\u01b0\u1ee3ng flash SSD \u0111\u00e3 \u0111\u01b0\u1ee3c c\u1ea3i thi\u1ec7n r\u1ea5t nhanh ch\u00f3ng. Tin x\u1ea5u l\u00e0 kh\u00f4ng c\u00f3 g\u00ec l\u00e0 &#8220;d\u1ec5 \u0103n&#8221; c\u1ea3 v\u00e0 c\u1ea7n c\u00f3 s\u1ef1 \u0111\u00e1nh \u0111\u1ed5i \u0111\u00e1ng k\u1ec3 v\u1edbi nh\u1eefng c\u00f4ng ngh\u1ec7 n\u00e0y.<\/p>\n<figure id=\"attachment_6475\" aria-describedby=\"caption-attachment-6475\" style=\"width: 461px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f43915732346-e1598318531200.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-6475 size-full\" src=\"https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f43915732346-e1598318531200.jpg\" alt=\"\" width=\"461\" height=\"276\" srcset=\"https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f43915732346-e1598318531200.jpg 461w, https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f43915732346-e1598318531200-300x180.jpg 300w\" sizes=\"auto, (max-width: 461px) 100vw, 461px\" \/><\/a><figcaption id=\"caption-attachment-6475\" class=\"wp-caption-text\">Flash nhi\u1ec1u l\u1edbp kh\u00e1c r\u1ea5t nhi\u1ec1u so v\u1edbi flash m\u1ed9t l\u1edbp v\u1ec1 \u0111\u1ed9 b\u1ec1n.<\/figcaption><\/figure>\n<h3>\u0110\u00e1nh \u0111\u1ed5i gi\u1eefa l\u1ed7i d\u1eef li\u1ec7u v\u00e0 hi\u1ec7u su\u1ea5t<\/h3>\n<p>Nhi\u1ec1u bit h\u01a1n tr\u00ean m\u1ed7i \u00f4 \u1ea3nh h\u01b0\u1edfng ti\u00eau c\u1ef1c \u0111\u00e1ng k\u1ec3 \u0111\u1ebfn l\u1ed7i \u0111\u1ecdc ghi d\u1eef li\u1ec7u, hi\u1ec7u su\u1ea5t, \u0111\u1ed9 b\u1ec1n v\u00e0 \u0111\u1ed9 tin c\u1eady. M\u1ed7i bit b\u1ed5 sung tr\u00ean m\u1ed7i \u00f4 s\u1ebd m\u1ea5t nhi\u1ec1u th\u1eddi gian h\u01a1n \u0111\u1ec3 ghi v\u00e0 \u0111\u1ecdc t\u1eeb m\u1ed9t \u00f4. N\u00f3 \u0111\u00f2i h\u1ecfi nhi\u1ec1u \u0111i\u1ec7n \u00e1p h\u01a1n \u0111\u1ec3 t\u1ea1o v\u00e0 ph\u00e2n bi\u1ec7t c\u00e1c tr\u1ea1ng th\u00e1i trong t\u1ebf b\u00e0o. \u0110i\u1ec1u n\u00e0y l\u00e0 do gi\u00e1 tr\u1ecb tr\u1ea1ng th\u00e1i b\u1ed5 sung l\u00e0m cho vi\u1ec7c x\u00e1c \u0111\u1ecbnh gi\u00e1 tr\u1ecb d\u01b0\u01a1ng kh\u00f3 kh\u0103n h\u01a1n. Ngo\u00e0i ra, nhi\u1ec7t \u0111\u1ed9 cao h\u01a1n g\u00e2y ra r\u00f2 r\u1ec9 \u0111i\u1ec7n t\u1eed nhi\u1ec1u h\u01a1n trong c\u00e1c cell v\u00ec \u0111\u1ed9 nh\u1ea1y cao h\u01a1n c\u1ea7n thi\u1ebft \u0111\u1ec3 ph\u00e2n bi\u1ec7t c\u00e1c tr\u1ea1ng th\u00e1i. K\u1ebft qu\u1ea3 l\u00e0 ph\u1ea1m vi nhi\u1ec7t \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng h\u1eb9p h\u01a1n khi bit tr\u00ean m\u1ed7i \u00f4 t\u0103ng l\u00ean. \u0110i\u1ec1u n\u00e0y d\u1eabn \u0111\u1ebfn t\u1ef7 l\u1ec7 l\u1ed7i cao h\u01a1n nhi\u1ec1u, hay c\u00f2n g\u1ecdi l\u00e0 h\u1ecfng d\u1eef li\u1ec7u.<\/p>\n<p>Hi\u1ec7u qu\u1ea3 th\u1ef1c s\u1ef1 l\u00e0 b\u1ed9 \u0111i\u1ec1u khi\u1ec3n flash ph\u1ea3i t\u00edch h\u1ee3p \u0111\u01b0\u1ee3c c\u00f4ng ngh\u1ec7 kh\u1eafc ph\u1ee5c l\u1ed7i to\u00e0n di\u1ec7n v\u1edbi m\u1ed7i bit b\u1ed5 sung. Khi s\u1ed1 l\u01b0\u1ee3t y\u00eau c\u1ea7u s\u1eeda l\u1ed7i t\u0103ng l\u00ean, v\u00e0 v\u00ec v\u1eady, th\u1eddi gian c\u1ea7n thi\u1ebft \u0111\u1ec3 th\u1ef1c hi\u1ec7n s\u1eeda d\u1eef li\u1ec7u v\u1edbi m\u1ed7i bit s\u1ebd \u0111\u01b0\u1ee3c c\u1ed9ng v\u00e0o. \u0110\u00e2y l\u00e0 l\u00fd do ch\u00ednh khi\u1ebfn \u0111\u1ed9 tr\u1ec5 t\u0103ng l\u00ean v\u00e0 IOPS gi\u1ea3m khi s\u1ed1 bit tr\u00ean m\u1ed7i \u00f4 t\u0103ng l\u00ean. C\u00f4ng ngh\u1ec7 3D-layering t\u0103ng IOPS tr\u00ean m\u1ed7i chip flash nh\u01b0ng kh\u00f4ng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn \u0111\u1ed9 tr\u1ec5.<\/p>\n<p>Hi\u1ec7u su\u1ea5t c\u1ee7a Flash SSD b\u1ecb \u1ea3nh h\u01b0\u1edfng chung h\u01a1n l\u00e0 ch\u1ec9 do c\u00e1c cell NAND flash. Dynamic RAM (DRAM) ho\u1eb7c persistent memory cache trong \u1ed5 c\u1ee9ng c\u00f3 \u1ea3nh h\u01b0\u1edfng r\u1ea5t l\u1edbn \u0111\u1ebfn hi\u1ec7u su\u1ea5t c\u1ee7a SSD. T\u00ednh n\u0103ng d\u1ef1 ph\u00f2ng qu\u00e1 m\u1ee9c (overprovisioning) c\u1ee7a Flash SSD c\u0169ng c\u00f3 \u1ea3nh h\u01b0\u1edfng l\u1edbn \u0111\u1ebfn hi\u1ec7u su\u1ea5t.<\/p>\n<blockquote>\n<h4>Chi ti\u1ebft h\u01a1n v\u1ec1 b\u1ed9 nh\u1edb flash NAND<\/h4>\n<p>NAND flash l\u00e0 m\u1ed9t c\u00f4ng ngh\u1ec7 b\u1ed9 nh\u1edb ph\u00e1 h\u1ee7y(destructive). M\u1ed7i khi m\u1ed9t \u00f4 nh\u1edb b\u1ecb ghi \u0111\u00e8, tr\u01b0\u1edbc ti\u00ean n\u00f3 ph\u1ea3i \u0111\u01b0\u1ee3c x\u00f3a. Flash NAND kh\u00f4ng ph\u1ea3i l\u00e0 m\u1ed9t c\u00f4ng ngh\u1ec7 t\u1eeb t\u00ednh. Vi\u1ec7c x\u00f3a n\u00f3 \u0111\u00f2i h\u1ecfi m\u1ed9t l\u1edbp n\u1ec1n b\u1ed9 nh\u1edb \u0111\u01b0\u1ee3c ph\u00e1 h\u1ee7y. Vi\u1ec7c \u0111\u1ecdc kh\u00f4ng g\u00e2y ra b\u1ea5t k\u1ef3 hao m\u00f2n \u00f4 nh\u1edb n\u00e0o. Do \u0111\u00f3, nguy\u00ean t\u1eafc chung cho flash NAND l\u00e0 ghi th\u00ec t\u1ed1n k\u00e9m nh\u01b0ng \u0111\u1ecdc th\u00ec mi\u1ec5n ph\u00ed. Vi\u1ec7c ghi c\u00f3 th\u1ec3 m\u1ea5t nhi\u1ec1u th\u1eddi gian n\u1ebfu ph\u1ea3i \u0111\u1ee3i qu\u00e1 tr\u00ecnh t\u1ea9y x\u00f3a x\u1ea3y ra. D\u1ef1 ph\u00f2ng th\u1eeba (Overprovisioning) c\u00f3 ngh\u0129a l\u00e0 c\u00f3 m\u1ed9t nh\u00f3m c\u00e1c \u00f4 m\u1edbi ho\u1eb7c \u0111\u00e3 b\u1ecb x\u00f3a tr\u01b0\u1edbc \u0111\u00f3 \u0111ang ch\u1edd ghi m\u1edbi, do \u0111\u00f3, thao t\u00e1c ghi kh\u00f4ng c\u1ea7n ph\u1ea3i \u0111\u1ee3i. SSD flash li\u00ean t\u1ee5c theo d\u00f5i c\u00e1c &#8220;erase block&#8221; c\u1ee7a ch\u01b0\u01a1ng tr\u00ecnh. Khi d\u1eef li\u1ec7u tr\u00ean m\u1ed9t erase block h\u1ebft tu\u1ed5i v\u00ec c\u00e1c phi\u00ean b\u1ea3n m\u1edbi h\u01a1n c\u1ee7a d\u1eef li\u1ec7u \u0111\u00f3 \u0111\u00e3 \u0111\u01b0\u1ee3c ghi v\u00e0o c\u00e1c erase block kh\u00e1c, b\u1ed9 \u0111i\u1ec1u khi\u1ec3n flash SSD s\u1ebd th\u1ef1c hi\u1ec7n thu d\u1ecdn r\u00e1c.<\/p><\/blockquote>\n<p>Giao di\u1ec7n flash SSD c\u0169ng c\u00f3 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn hi\u1ec7u su\u1ea5t. NVMe l\u00e0 m\u1ed9t giao di\u1ec7n nhanh h\u01a1n nhi\u1ec1u so v\u1edbi SATA ho\u1eb7c SAS. Giao di\u1ec7n v\u00e0 ki\u1ebfn tr\u00fac l\u01b0u tr\u1eef \u0111\u01b0\u1ee3c chia s\u1ebb c\u0169ng c\u00f3 \u1ea3nh h\u01b0\u1edfng r\u1ea5t l\u1edbn \u0111\u1ebfn hi\u1ec7u su\u1ea5t. Ki\u1ebfn tr\u00fac v\u1edbi DRAM, b\u1ed9 nh\u1edb l\u1edbp l\u01b0u tr\u1eef ho\u1eb7c SLC caching ho\u1eb7c c\u00f4ng ngh\u1ec7 ph\u00e2n t\u1ea7ng l\u01b0u tr\u1eef s\u1ebd c\u1ea3i thi\u1ec7n v\u1ea5n \u0111\u1ec1 hi\u1ec7u su\u1ea5t. K\u1ebft n\u1ed1i m\u1ea1ng l\u01b0u tr\u1eef c\u0169ng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn hi\u1ec7u su\u1ea5t. NVMe-oF tr\u00ean Ethernet, Fibre Channel, Infiniband ho\u1eb7c TCP\/IP c\u0169ng s\u1ebd c\u1ea3i thi\u1ec7n hi\u1ec7u su\u1ea5t. N\u00f3 kh\u00f4ng ch\u1ec9 \u0111\u01a1n thu\u1ea7n v\u1ec1 c\u00f4ng ngh\u1ec7 SSD flash.<\/p>\n<h3>\u0110\u00e1nh \u0111\u1ed5i \u1edf \u0111\u1ed9 b\u1ec1n v\u00e0 \u0111\u1ed9 tin c\u1eady<\/h3>\n<p>M\u1ed7i bit \u0111\u01b0\u1ee3c th\u00eam v\u00e0o c\u00e1c \u00f4 NAND flash l\u00e0m gi\u1ea3m \u0111\u1ed9 b\u1ec1n theo m\u1ed9t th\u1ee9 t\u1ef1 l\u1edbn d\u1ea7n ho\u1eb7c 10 l\u1ea7n. \u0110\u1ed9 b\u1ec1n c\u1ee7a \u00f4 Flash NAND \u0111\u01b0\u1ee3c \u0111o b\u1eb1ng s\u1ed1 l\u1ea7n ghi tr\u01b0\u1edbc khi t\u1ebf b\u00e0o b\u1ecb m\u00f2n. SLC \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 \u1edf m\u1ee9c x\u1ea5p x\u1ec9 100.000 chu k\u1ef3 ghi tr\u00ean m\u1ed7i \u00f4. MLC \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 \u1edf kho\u1ea3ng 10.000 chu k\u1ef3 ghi. TLC \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 \u1edf kho\u1ea3ng 1.000 chu k\u1ef3 ghi. QLC \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 \u1edf kho\u1ea3ng 100 chu k\u1ef3 ghi. V\u00e0 PLC \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 l\u00e0 c\u00f3 kho\u1ea3ng 10 chu k\u1ef3 ghi.<\/p>\n<p>\u0110\u1ed9 b\u1ec1n c\u1ee7a cell v\u00e0 \u0111\u1ed9 b\u1ec1n chung c\u1ee7a c\u1ea3 \u1ed5 c\u1ee9ng flash SSD kh\u00f4ng gi\u1ed1ng nhau. Hai y\u1ebfu t\u1ed1 ch\u00ednh \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn \u0111\u1ed9 b\u1ec1n c\u1ee7a flash SSD l\u00e0 hi\u1ec7u qu\u1ea3 c\u1ee7a thu\u1eadt to\u00e1n c\u00e2n b\u1eb1ng \u0111\u1ed9 m\u00f2n c\u1ee7a b\u1ed9 \u0111i\u1ec1u khi\u1ec3n flash v\u00e0 t\u1ed5ng l\u01b0\u1ee3ng NAND flash trong SSD. Dung l\u01b0\u1ee3ng flash \u0111\u01b0\u1ee3c x\u1ebfp h\u1ea1ng theo SSD kh\u00f4ng ph\u1ea3n \u00e1nh t\u1ed5ng dung l\u01b0\u1ee3ng flash trong SSD. C\u00f3 m\u1ed9t dung l\u01b0\u1ee3ng d\u1ef1 ph\u00f2ng c\u1ee7a flash NAND \u0111\u00e1ng k\u1ec3 trong SSD. Vi\u1ec7c d\u1ef1 ph\u00f2ng th\u1eeba \u0111\u00f3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 thay th\u1ebf cho c\u00e1c \u00f4 nh\u1edb \u0111\u00e3 b\u1ecb m\u00f2n. S\u1ed1 l\u01b0\u1ee3ng d\u1ef1 ph\u00f2ng th\u1eeba c\u1ee7a c\u00e1c flash SSD l\u00e0 kh\u00e1c nhau. N\u00f3i chung, khi s\u1ed1 bit tr\u00ean m\u1ed7i \u00f4 t\u0103ng l\u00ean, th\u00ec vi\u1ec7c d\u1ef1 ph\u00f2ng th\u1eeba c\u1ee7a flash SSD c\u0169ng v\u1eady. Dung l\u01b0\u1ee3ng l\u1edbn h\u01a1n t\u01b0\u01a1ng \u0111\u01b0\u01a1ng v\u1edbi nhi\u1ec1u t\u1ebf b\u00e0o h\u01a1n \u1edf m\u1ee9c \u0111\u1ed9 hao m\u00f2n, gi\u00fap t\u0103ng \u0111\u1ed9 b\u1ec1n c\u1ee7a SSD.<\/p>\n<figure id=\"attachment_6476\" aria-describedby=\"caption-attachment-6476\" style=\"width: 426px\" class=\"wp-caption aligncenter\"><a href=\"https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f439158664e1-e1598318573547.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-6476 size-full\" src=\"https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f439158664e1-e1598318573547.jpg\" alt=\"\" width=\"426\" height=\"392\" srcset=\"https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f439158664e1-e1598318573547.jpg 426w, https:\/\/thegioimaychu.vn\/blog\/wp-content\/uploads\/2020\/08\/tgmc-blog-5f439158664e1-e1598318573547-300x276.jpg 300w\" sizes=\"auto, (max-width: 426px) 100vw, 426px\" \/><\/a><figcaption id=\"caption-attachment-6476\" class=\"wp-caption-text\">SLC, MLC, TLC v\u00e0 QLC flash c\u00f3 c\u00e1c m\u1ee9c hi\u1ec7u su\u1ea5t v\u00e0 m\u1ee9c gi\u00e1 kh\u00e1c nhau.<\/figcaption><\/figure>\n<p>\u0110\u1ed9 b\u1ec1n c\u1ee7a Flash SSD th\u01b0\u1eddng \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 \u1edf m\u1ee9c terabytes written (TBW). N\u00f3 c\u0169ng \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 theo s\u1ed1 l\u1ea7n ghi \u1ed5 c\u1ee9ng m\u1ed7i ng\u00e0y (drive writes per day, DWPD). DWPD d\u1ecbch th\u00e0nh TBW. C\u00e1c nh\u00e0 cung c\u1ea5p b\u1ea3o h\u00e0nh \u1ed5 c\u1ee9ng c\u1ee7a h\u1ecd theo DWPD ho\u1eb7c TBW. T\u00f3m l\u1ea1i, \u0111\u00f3 l\u00e0 l\u01b0\u1ee3ng d\u1eef li\u1ec7u c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c ghi v\u00e0o SSD flash tr\u01b0\u1edbc khi n\u00f3 c\u1ea1n ki\u1ec7t. V\u00ed d\u1ee5: \u1ed5 \u0111\u0129a 3D TLC 1 TB \u0111\u01b0\u1ee3c x\u1ebfp h\u1ea1ng v\u00e0 b\u1ea3o h\u00e0nh \u1edf m\u1ee9c .66 DWPD s\u1ebd c\u00f3 \u0111\u1ecbnh m\u1ee9c x\u1ea5p x\u1ec9 1.200 TBW. Nh\u01b0 th\u1ebf l\u00e0 c\u00f3 r\u1ea5t nhi\u1ec1u l\u1ea7n ghi trong kho\u1ea3ng th\u1eddi gian \u0111\u00f3.<\/p>\n<p>Nh\u01b0ng n\u1ebfu \u1ed5 1 TB l\u00e0 3D QLC th\u00ec sao? N\u00f3 s\u1ebd c\u00f3 gi\u00e1 th\u1ea5p h\u01a1n nhi\u1ec1u, nh\u01b0ng n\u00f3 c\u00f3 kh\u1ea3 n\u0103ng c\u00f3 DWPD v\u00e0 TBW th\u1ea5p h\u01a1n nhi\u1ec1u \u1edf m\u1ee9c kho\u1ea3ng 10% ho\u1eb7c 120 TBW. Con s\u1ed1 \u0111\u00f3 c\u00f3 th\u1ec3 t\u0103ng l\u00ean n\u1ebfu l\u01b0\u1ee3ng d\u1ef1 ph\u00f2ng c\u0169ng t\u0103ng l\u00ean.<\/p>\n<h3>SLC, MLC, TLC, QLC v\u00e0 PLC: C\u00e1ch ch\u1ecdn lo\u1ea1i c\u00f4ng ngh\u1ec7 l\u01b0u tr\u1eef SSD ph\u00f9 h\u1ee3p v\u1edbi nhu c\u1ea7u c\u1ee7a b\u1ea1n<\/h3>\n<p>L\u1ef1a ch\u1ecdn \u1ed5 l\u01b0u tr\u1eef NAND flash ph\u00f9 h\u1ee3p ph\u1ee5 thu\u1ed9c v\u00e0o dung l\u01b0\u1ee3ng, chi ph\u00ed, hi\u1ec7u su\u1ea5t, m\u1ee9c l\u1ed7i v\u00e0 \u0111\u1ed9 b\u1ec1n.<\/p>\n<p>SSD flash PLC th\u01b0\u1eddng c\u00f3 chi ph\u00ed th\u1ea5p nh\u1ea5t cho m\u1ed7i gigabyte nh\u01b0ng c\u00f3 nh\u1eefng h\u1ea1n ch\u1ebf nghi\u00eam tr\u1ecdng v\u1ec1 \u0111\u1ed9 b\u1ec1n. Hi\u1ec7u su\u1ea5t s\u1ebd t\u1ed1t h\u01a1n b\u1ea5t k\u1ef3 <a class=\"iblink\" href=\"\/linh-kien-may-chu\/hdd\/\">\u1ed5 c\u1ee9ng HDD<\/a> n\u00e0o v\u00e0 th\u1ea5p h\u01a1n \u0111\u00e1ng k\u1ec3 so v\u1edbi b\u1ea5t k\u1ef3 lo\u1ea1i SSD flash n\u00e0o kh\u00e1c. N\u00f3 r\u00f5 r\u00e0ng l\u00e0 nh\u1eb1m m\u1ee5c \u0111\u00edch l\u01b0u tr\u1eef c\u00e1c lo\u1ea1i d\u1eef li\u1ec7u kh\u00f4ng thay \u0111\u1ed5i nhi\u1ec1u, n\u1ebfu c\u00f3: d\u1eef li\u1ec7u l\u01b0u gi\u1eef, cold data v\u00e0 th\u1eadm ch\u00ed cool data. C\u00e1c SSD flash PLC c\u00f3 c\u00f9ng h\u1ea1ng v\u1edbi m\u1ed9t s\u1ed1 c\u00f4ng ngh\u1ec7 write-once-read-many kh\u00e1c.<\/p>\n<p>N\u1ebfu m\u1ed9t \u1ee9ng d\u1ee5ng c\u1ea7n hi\u1ec7u su\u1ea5t t\u1ed1t nh\u1ea5t c\u00f3 th\u1ec3, SSD flash SLC l\u00e0 s\u1ef1 l\u1ef1a ch\u1ecdn. Tuy nhi\u00ean, lo\u1ea1i <a class=\"iblink\" href=\"\/storage\/\">thi\u1ebft b\u1ecb l\u01b0u tr\u1eef<\/a> s\u1eed d\u1ee5ng SLC l\u1ea1i quan tr\u1ecdng. M\u1ed9t m\u1ea3ng l\u01b0u tr\u1eef s\u1eed d\u1ee5ng SSD flash SLC l\u00e0m b\u1ed9 nh\u1edb \u0111\u1ec7m ho\u1eb7c l\u00e0m ph\u01b0\u01a1ng ti\u1ec7n l\u01b0u tr\u1eef ch\u00ednh c\u1ee7a n\u00f3 s\u1ebd kh\u00f4ng nhanh h\u01a1n \u0111\u00e1ng k\u1ec3 so v\u1edbi m\u1ea3ng l\u01b0u tr\u1eef s\u1eed d\u1ee5ng SSD MLC ho\u1eb7c TLC. \u0110i\u1ec1u n\u00e0y l\u00e0 do t\u1eafc ngh\u1ebdn \u0111\u1ed9 tr\u1ec5 trong \u0111\u01b0\u1eddng truy\u1ec1n d\u1eef li\u1ec7u c\u1ee7a SSD, bao g\u1ed3m b\u1ed9 \u0111i\u1ec1u khi\u1ec3n SATA ho\u1eb7c NVMe, b\u1ed9 \u0111i\u1ec1u khi\u1ec3n <a class=\"iblink\" href=\"\/storage\/\">h\u1ec7 th\u1ed1ng l\u01b0u tr\u1eef<\/a>, m\u1ea1ng l\u01b0u tr\u1eef ho\u1eb7c li\u1ec7u h\u1ec7 th\u1ed1ng c\u00f3 ph\u1ea3i l\u00e0 NVMe-oF gi\u1eefa application server v\u00e0 storage server, v\u00e0 bus d\u1eef li\u1ec7u c\u1ee7a application server. S\u1ef1 kh\u00e1c bi\u1ec7t v\u1ec1 hi\u1ec7u su\u1ea5t trong k\u1ecbch b\u1ea3n SSD SLC so v\u1edbi MLC n\u00e0y s\u1ebd r\u1ea5t kh\u00f3 \u0111\u1ec3 ch\u1ee9ng minh v\u1ec1 m\u1eb7t t\u00e0i ch\u00ednh. Ng\u01b0\u1ee3c l\u1ea1i, m\u1ed9t SLC PCIe card trong m\u1ed9t m\u00e1y ch\u1ee7 application ho\u1eb7c m\u1ed9t thi\u1ebft b\u1ecb l\u01b0u tr\u1eef d\u1eef li\u1ec7u d\u1ef1a tr\u00ean SLC g\u1eafn li\u1ec1n v\u1edbi m\u1ea1ng, th\u1ec3 hi\u1ec7n hi\u1ec7u su\u1ea5t r\u1ea5t l\u1edbn l\u1ee3i th\u1ebf h\u01a1n c\u00e1c s\u1ea3n ph\u1ea9m MLC t\u01b0\u01a1ng \u0111\u01b0\u01a1ng. V\u00ed d\u1ee5 v\u1ec1 SLC n\u00e0y gi\u1ea3i th\u00edch h\u01a1n.<\/p>\n<p>Vi\u1ec7c quy\u1ebft \u0111\u1ecbnh lo\u1ea1i c\u00f4ng ngh\u1ec7 l\u01b0u tr\u1eef flash n\u00e0o &#8211; c\u0169ng nh\u01b0 thi\u1ebft b\u1ecb n\u00e0o &#8211; s\u1ebd s\u1eed d\u1ee5ng \u0111\u00f2i h\u1ecfi ph\u1ea3i c\u00e2n nh\u1eafc s\u1ef1 \u0111\u00e1nh \u0111\u1ed5i. Hi\u1ec7u su\u1ea5t ph\u1ee5 c\u00f3 c\u1ea7n thi\u1ebft kh\u00f4ng? Dung l\u01b0\u1ee3ng c\u00f3 quan tr\u1ecdng h\u01a1n kh\u00f4ng? Chi ph\u00ed \u0111\u00f3ng vai tr\u00f2 g\u00ec trong quy\u1ebft \u0111\u1ecbnh \u0111\u00f3? \u0110i\u1ec1u g\u00ec v\u1ec1 ph\u1ea7n m\u1ec1m c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng hi\u1ec7u qu\u1ea3 c\u00f4ng ngh\u1ec7 flash? N\u00f3 c\u00f3 ti\u00eau t\u1ed1n nhi\u1ec1u chu k\u1ef3 CPU \u1ee9ng d\u1ee5ng h\u01a1n kh\u00f4ng? L\u01b0u \u00fd r\u1eb1ng flash NVMe card \u0111\u00e1nh \u0111\u1ed5i hi\u1ec7u su\u1ea5t cao h\u01a1n v\u1edbi m\u1ee9c ti\u00eau th\u1ee5 t\u00e0i nguy\u00ean CPU cao h\u01a1n t\u1edbi 20%.<\/p>\n<p>D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 quy t\u1eafc chung v\u1ec1 SSD, nh\u01b0ng h\u00e3y nh\u1edb r\u1eb1ng nh\u1eefng quy t\u1eafc n\u00e0y kh\u00f4ng ph\u1ea3i l\u00fac n\u00e0o c\u0169ng \u00e1p d\u1ee5ng.<\/p>\n<ul>\n<li>Khi hi\u1ec7u su\u1ea5t t\u0103ng t\u1ed1c \u1ee9ng d\u1ee5ng ph\u1ea3i cao nh\u1ea5t c\u00f3 th\u1ec3 &#8211; v\u1edbi \u0111\u1ed9 tr\u1ec5 th\u1ea5p nh\u1ea5t c\u00f3 th\u1ec3 &#8211; v\u00e0 gi\u00e1 c\u1ea3 kh\u00f4ng ph\u1ea3i l\u00e0 m\u1ed9t y\u1ebfu t\u1ed1 quan tr\u1ecdng, th\u00ec \u1ed5 SSD flash NVMe SLC l\u00e0 m\u1ed9t c\u00e2u tr\u1ea3 l\u1eddi r\u1ea5t t\u1ed1t. Ch\u00fang kh\u00f4ng ph\u1ea3i l\u00e0 c\u00e2u tr\u1ea3 l\u1eddi duy nh\u1ea5t, nh\u01b0 c\u00e1ch \u0111\u00e2y ch\u1ec9 v\u00e0i n\u0103m. \u1ed4 c\u1ee9ng\u00a0d\u1ea1ng storage class memory c\u1ee7a 3D Xpoint nhanh h\u01a1n t\u1edbi b\u1ed1n l\u1ea7n v\u1edbi chi ph\u00ed g\u1ea5p 10 l\u1ea7n. C\u00e1c m\u00f4-\u0111un b\u1ed9 nh\u1edb li\u00ean t\u1ee5c c\u1ee7a data center ch\u1ea1y \u1edf ch\u1ebf \u0111\u1ed9 tr\u1ef1c ti\u1ebfp \u1ee9ng d\u1ee5ng nhanh h\u01a1n 10 l\u1ea7n v\u1edbi chi ph\u00ed g\u1ea5p 10 l\u1ea7n.<\/li>\n<li>Khi t\u0103ng t\u1ed1c \u1ee9ng d\u1ee5ng l\u00e0 quan tr\u1ecdng, nh\u01b0ng chi ph\u00ed l\u00e0 m\u1ed9t v\u1ea5n \u0111\u1ec1, MLC, TLC v\u00e0 \u1edf m\u1ee9c \u0111\u1ed9 th\u1ea5p h\u01a1n, QLC, l\u00e0 nh\u1eefng l\u1ef1a ch\u1ecdn thay th\u1ebf kh\u1ea3 thi.<\/li>\n<li>Khi y\u00eau c\u1ea7u ph\u1ea3i c\u00f3 m\u1ed9t h\u1ec7 th\u1ed1ng l\u01b0u tr\u1eef chia s\u1ebb hi\u1ec7u su\u1ea5t cao, th\u00ec ki\u1ebfn tr\u00fac h\u1ec7 th\u1ed1ng l\u01b0u tr\u1eef quan tr\u1ecdng h\u01a1n l\u00e0 ch\u1ec9 v\u1ec1 m\u1eb7t ph\u01b0\u01a1ng ti\u1ec7n SSD flash. K\u1ebft n\u1ed1i NVMe-oF tr\u00ean Ethernet, Fibre Channel, Infiniband ho\u1eb7c TCP \/ IP; c\u00e1ch d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c l\u01b0u v\u00e0o b\u1ed9 nh\u1edb \u0111\u1ec7m ho\u1eb7c ph\u00e2n c\u1ea5p l\u00e0 nh\u1eefng v\u1ea5n \u0111\u1ec1 l\u1edbn h\u01a1n. SLC, MLC, TLC, QLC v\u00e0 PLC \u0111\u1ec1u kh\u1ea3 thi. M\u1ed9t s\u1ed1 h\u1ec7 th\u1ed1ng l\u01b0u tr\u1eef tr\u00ean th\u1ecb tr\u01b0\u1eddng, ch\u1eb3ng h\u1ea1n nh\u01b0 h\u1ec7 th\u1ed1ng c\u1ee7a VAST, \u0111\u00e3 ch\u1ee9ng minh \u0111i\u1ec1u n\u00e0y v\u1edbi QLC.<\/li>\n<li>Khi chi ph\u00ed cho m\u1ed7i gigabyte l\u00e0 t\u1ed1i quan tr\u1ecdng, th\u00ec hi\u1ec7u su\u1ea5t c\u0169ng quan tr\u1ecdng, nh\u01b0ng kh\u00f4ng quan tr\u1ecdng b\u1eb1ng v\u00e0 \u0111\u1ed9 b\u1ec1n ghi kh\u00f4ng ph\u1ea3i l\u00e0 y\u1ebfu t\u1ed1 l\u1edbn &#8211; do v\u1ea5n \u0111\u1ec1 caching v\u00e0 writing &#8211; MLC, TLC (v\u00e0 c\u1ea3 QLC) c\u00f3 th\u1ec3 l\u00e0 l\u1ef1a ch\u1ecdn ph\u00f9 h\u1ee3p.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>C&ugrave;ng t&igrave;m hi&#7875;u s&#7921; kh&aacute;c bi&#7879;t quan tr&#7885;ng v&#7873; dung l&#432;&#7907;ng, hi&#7879;u su&#7845;t v&agrave; &#273;&#7897; tin c&#7853;y gi&#7919;a c&aacute;c c&ocirc;ng ngh&#7879; l&#432;u tr&#7919; &#273;a l&#7899;p multi-layer SSD \/ flash storage khi trang b&#7883; &#7893; c&#7913;ng SSD v&agrave;o h&#7879; th&#7889;ng c&#7911;a c&#7911;a b&#7841;n. C&aacute;c &#7893; c&#7913;ng SSD, hay c&ograve;n g&#7885;i l&agrave; NAND flash, hi&#7879;n v&#7851;n &#273;ang&#8230;<\/p>\n","protected":false},"author":2,"featured_media":6478,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[1],"tags":[],"class_list":["post-6473","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tong-hop"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>T\u00ecm hi\u1ec3u s\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa c\u00e1c c\u00f4ng ngh\u1ec7 l\u01b0u tr\u1eef multi-layer SSD: SLC, MLC, TLC, QLC v\u00e0 PLC - Blog | TheGioiMayChu<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/thegioimaychu.vn\/blog\/tong-hop\/tim-hieu-su-khac-biet-giua-cac-cong-nghe-luu-tru-multi-layer-ssd-slc-mlc-tlc-qlc-va-plc-p6473\/\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:title\" content=\"T\u00ecm hi\u1ec3u s\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa c\u00e1c c\u00f4ng ngh\u1ec7 l\u01b0u tr\u1eef multi-layer SSD: SLC, MLC, TLC, QLC v\u00e0 PLC - Blog | TheGioiMayChu\" \/>\n<meta name=\"twitter:description\" content=\"C&ugrave;ng t&igrave;m hi&#7875;u s&#7921; kh&aacute;c bi&#7879;t quan tr&#7885;ng v&#7873; dung l&#432;&#7907;ng, hi&#7879;u su&#7845;t v&agrave; &#273;&#7897; tin c&#7853;y gi&#7919;a c&aacute;c c&ocirc;ng ngh&#7879; l&#432;u tr&#7919; &#273;a l&#7899;p multi-layer SSD \/ flash storage khi trang b&#7883; &#7893; c&#7913;ng SSD v&agrave;o h&#7879; th&#7889;ng c&#7911;a c&#7911;a b&#7841;n. 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