{"id":359,"date":"2022-04-11T11:44:11","date_gmt":"2022-04-11T02:44:11","guid":{"rendered":"https:\/\/www.hagisol.com\/techblog\/?p=359"},"modified":"2023-02-09T09:37:10","modified_gmt":"2023-02-09T00:37:10","slug":"post-359","status":"publish","type":"post","link":"https:\/\/www.hagisol.com\/techblog\/?p=359","title":{"rendered":"How to choose an SSD (1\/5): TBW is determined by how you use it!"},"content":{"rendered":"\n<div class=\"is-layout-flex wp-block-buttons\">\n<div class=\"wp-block-button has-custom-width wp-block-button__width-50\"><a class=\"wp-block-button__link has-white-color has-vivid-cyan-blue-background-color has-text-color has-background wp-element-button\" href=\"https:\/\/www.hagisol.com\/form\/contact.php\">Click here to contact us<\/a><\/div>\n<\/div>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/www.hagisol.com\/techblog\/wp-content\/uploads\/2022\/02\/surprise-ssd.jpeg\" alt=\"\" class=\"wp-image-368\"\/><\/figure>\n\n\n\n<h2 id=\"outline__1\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Products related to this article<\/mark><\/h2>\n\n\n\n<ul>\n<li><a rel=\"noreferrer noopener\" href=\"https:\/\/www.hagisol.com\/products\/storage\" target=\"_blank\">Flash Storage Products<\/a><\/li>\n<\/ul>\n\n\n\n<h2 id=\"outline__2\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Introduction<\/mark><\/h2>\n\n\n\n<p>When selecting a storage device, data access performance, price, and longevity are often the key points.<\/p>\n\n\n\n<p>\u3000Especially in the case of Solid State Drives (SSDs), which use NAND flash memory as their nonvolatile storage medium, longevity can be one of the main criteria.<\/p>\n\n\n\n<p>\u3000As is widely known, the product life of SSDs depends on the number of times a block of NAND flash memory (hereinafter simply referred to as &#8220;block&#8221;) can be rewritten, aside from damage due to improper use or dropping.<\/p>\n\n\n\n<p>\u3000Many people may think of Terabytes Written (TBW) as an indicator of SSD lifespan attributable to the number of times a block is rewritten.<\/p>\n\n\n\n<p>\u3000<strong>However, TBW is a value when an SSD is used in a certain way (workload), and the value changes when the same SSD is used in different ways.<\/strong><\/p>\n\n\n\n<p>\u3000This is the same for both SATA and NVMe SSDs.<\/p>\n\n\n\n<p>\u3000For example, even if the product specification of an SSD states &#8220;TBW :500 TB,&#8221;<strong> it does not guarantee that 500 TB can be written from the host under any usage.<\/strong><\/p>\n\n\n\n<p>Therefore, in the next few articles, we will summarize the SSD selection criteria, including longevity.<\/p>\n\n\n\n<p>\u3000This article will define TBW and explain what TBW means in SSD product specifications.<\/p>\n\n\n\n<h2 id=\"outline__3\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Summary<\/mark><\/h2>\n\n\n\n<ul>\n<li>TBW in SSD product specifications are often calculated using JEDEC workloads (especially client workloads).<\/li>\n\n\n\n<li>TBW strongly depends on the workload, so the<strong> TBW in the product specifications may not be helpful.<\/strong><\/li>\n\n\n\n<li>It is <strong>dangerous<\/strong> to select a product by relying on the TBW in SSD product specifications.<\/li>\n<\/ul>\n\n\n\n<h2 id=\"outline__4\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">TBW is defined by JEDEC<\/mark><\/h2>\n\n\n\n<p>\u3000Terabytes Written (TBW) is defined by <a href=\"https:\/\/www.jedec.org\/\">JEDEC<\/a> in a specification called JESD218.\u00b9<\/p>\n\n\n\n<p>\u3000The definition of TBW in its JESD218 is shown in the figure below. \u00a0This is taken from the presentation material at the Flash Memory Summit held in August 2011.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/www.hagisol.com\/techblog\/wp-content\/uploads\/2022\/03\/definition-of-tbw-in-jesd218-1024x768.png\" alt=\"\" class=\"wp-image-420\"\/><figcaption class=\"wp-element-caption\">Figure: Definition of TBW in JESD218<\/figcaption><\/figure>\n\n\n\n<p>\u3000Conditions 1) to 4) are the basic functional requirements that SSDs should have as storage.<\/p>\n\n\n\n<p>\u3000It is possible because of this, the part<strong> &#8220;the maximum size that a host can write to an SSD&#8221;<\/strong> has become the sole focus, and this TBW is used as one of the indicators to compare SSDs in various situations.<\/p>\n\n\n\n<p>\u3000The problem with this is that the &#8220;using workloads for application classes&#8221; part is not taken into account. <strong>The existence of this description is evidence that TBW depends on workloads (i.e., usage).<\/strong><\/p>\n\n\n\n<p>\u3000In addition, the above &#8220;workloads for application classes&#8221; are usually defined by JEDEC in JESD219<sup>3<\/sup>. Specifically, there are two types of workloads: client workloads and enterprise workloads.<\/p>\n\n\n\n<h2 id=\"outline__5\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">What is a &#8220;client workload&#8221; under JESD 219?<\/mark><a href=\"https:\/\/qiita.com\/ken-yossy\/items\/27d2cdba22c58e9aa6f2#jesd219%E3%81%AE%E3%82%AF%E3%83%A9%E3%82%A4%E3%82%A2%E3%83%B3%E3%83%88%E3%83%AF%E3%83%BC%E3%82%AF%E3%83%AD%E3%83%BC%E3%83%89%E3%81%A8%E3%81%AF\"><\/a><\/h2>\n\n\n\n<p>\u3000A &#8220;client workload&#8221; as defined by JESD 219 is a workload for a &#8220;client SSD&#8221;.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" src=\"https:\/\/www.hagisol.com\/techblog\/wp-content\/uploads\/2022\/03\/workloads-and-ssd-applications-1024x768.png\" alt=\"\" class=\"wp-image-424\"\/><figcaption class=\"wp-element-caption\">Figure 4: Types of workloads defined by JESD 219 and their characteristics\u00b2<\/figcaption><\/figure>\n\n\n\n<p>\u3000<\/p>\n\n\n\n<p>The figure describes the client SSD workload (left side of the figure) as &#8220;running 8 hours a day, 7 days a week,&#8221; &#8220;bursty workload with fairly long rest times (time without host access to SSD),&#8221; &#8220;few writes,&#8221; &#8220;very localized access area (footprint) in total LBA space,&#8221; and &#8220;cost optimized.&#8221;<\/p>\n\n\n\n<p>\u3000All of these features are intended for SSDs installed in so-called office and home-use PCs, especially the system drive on which the OS is installed.<\/p>\n\n\n\n<p>\u3000Therefore, the TBW calculated using the JESD219 client workload is a value that can be used when selecting SSDs for office and home use PCs, especially for system drives where the OS is installed.<\/p>\n\n\n\n<p>\u3000The following table shows examples of how TBW calculated using JESD219 client workloads can be used as a reference and how it cannot be used as a reference.<br><\/p>\n\n\n\n<p><\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/www.hagisol.com\/techblog\/wp-content\/uploads\/2023\/02\/image-2.png\" alt=\"\" class=\"wp-image-1850\"\/><\/figure>\n\n\n\n<h2 id=\"outline__6\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Conclusion<\/mark><\/h2>\n\n\n\n<p>\u3000While TBW numbers are easy to use to compare products, if the workload used in the calculation does not match the actual workload in use, the comparison may be off the mark and the choice may not meet your requirements.<\/p>\n\n\n\n<p>\u3000In the next article, we will explain why TBW depends on your workload, and the factors that influence how large or small TBW is, and more.<\/p>\n\n\n\n<h2 id=\"outline__7\"><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-cyan-blue-color\">Reference<\/mark><\/h2>\n\n\n\n<ol>\n<li>JEDEC, <em>\u201cSolid-State Drive (SSD) Requirements and Endurance Test Method\u201d<\/em>, JESD218B.01, March, 2016<\/li>\n\n\n\n<li>Alvin Cox,&nbsp;<em>\u201cJEDEC SSD Endurance Workloads\u201d<\/em>, Flash Memory Summit 2011, Santa Clara, CA, August, 2011<\/li>\n\n\n\n<li>JEDEC,&nbsp;<em>\u201cSolid-State Drive (SSD) Endurance Workloads\u201d<\/em>, JESD219A, July, 2012<\/li>\n<\/ol>\n\n\n\n<p class=\"has-small-font-size\">Trademarks of Other Companies<br>Although registered trademark marks are not indicated in the articles, company names and product names appearing in the articles are generally trademarks or registered trademarks of the respective companies.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p class=\"has-small-font-size\">About the article<br>The content of this article is information at the time of publication. Please note that the information is subject to change without notice.<\/p>\n\n\n\n<h2 id=\"outline__8\" class=\"has-vivid-cyan-blue-color has-text-color\">Contact Us<\/h2>\n\n\n\n<p><\/p>\n\n\n\n<div class=\"is-layout-flex wp-block-buttons\">\n<div class=\"wp-block-button has-custom-width wp-block-button__width-50\"><a class=\"wp-block-button__link has-white-color has-vivid-cyan-blue-background-color has-text-color has-background wp-element-button\" href=\"https:\/\/www.hagisol.com\/form\/contact.php\">Click here to contact us<\/a><\/div>\n<\/div>\n\n\n\n<p><a href=\"https:\/\/qiita.com\/ken-yossy\/items\/27d2cdba22c58e9aa6f2#tbw%E3%81%A8%E3%81%AFjedec%E3%81%8C%E5%AE%9A%E7%BE%A9%E3%81%97%E3%81%9F%E3%82%82%E3%81%AE\"><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>TBW is often seen in SSD specifications. the value of TBW depends on &#8220;how SSD is used&#8221;. here are some points to understand and use TBW correctly.<\/p>\n","protected":false},"author":4,"featured_media":504,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[23,24],"_links":{"self":[{"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=\/wp\/v2\/posts\/359"}],"collection":[{"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=359"}],"version-history":[{"count":55,"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=\/wp\/v2\/posts\/359\/revisions"}],"predecessor-version":[{"id":1856,"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=\/wp\/v2\/posts\/359\/revisions\/1856"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=\/wp\/v2\/media\/504"}],"wp:attachment":[{"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=359"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=359"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hagisol.com\/techblog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}