since new disks exceed the old sector \/ heads \/ cylinder specs the makers have resorted to this “cheat”:<\/p>\n
sec = 255
\nheads = 63<\/p>\n
always, which is the max the parameters allow, and you vary the cyl number to increase its size (e.g. 243201 cyl for a 2000GB disk)<\/p>\n
now this leads to having the first user sec (after the bootsector, number zero!) to be at 255 x 63 sectors on cyl 1 => sector 16065 , which is NOT a multiple of 8, therefore NOT aligned, and all that follows is slow access<\/p>\n
move the beginning to the 64th sector, and the first partition starts at 255 x 64 => sector 16320 (which is 8 x 2040 ), and use for partitions’ cylinder count a multiple of 8
\n(that’s a “math cheat” to ensure the sector number will always be divisible by 8, since “anynumber x anothernumber x 8” will always be divisible by 8)<\/p>\n
in my case a WD20EARX the write speed went from 43MBs to 76MBs, read from 64MBs to 72MBs for a contingous 2GB file – wth an old PCI-SATA150 controller<\/p>\n
most important in all of this is that a filesystem cluster (4k size with NTFS, and ext3 linux) fits perfectly inside a physical 4k unit on the disk – and even when you still use 512 byte sectors once it’s aligned that improves speed, since you read 8 of those in one go<\/p>\n","protected":false},"excerpt":{"rendered":"
since new disks exceed the old sector \/ heads \/ cylinder specs the makers have resorted to this “cheat”: sec = 255 heads = 63 always, which is the max the parameters allow, and you vary the cyl number to increase its size (e.g. 243201 cyl for a 2000GB disk) now this leads to having […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-184","post","type-post","status-publish","format-standard","hentry","category-hardware-stuff"],"_links":{"self":[{"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=\/wp\/v2\/posts\/184","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=184"}],"version-history":[{"count":7,"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=\/wp\/v2\/posts\/184\/revisions"}],"predecessor-version":[{"id":258,"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=\/wp\/v2\/posts\/184\/revisions\/258"}],"wp:attachment":[{"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=184"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=184"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.zokul.com\/zokulblog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=184"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}