This is a multi-part message in MIME format. --------------2B4B839116333F84136665DD Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit What you mentioned is a specific case and not a generic situation. The main point there is that RAID 5 or 6 impacts write performance compared when you write to only 2 given disks at a time. That was the comparison made. Fernando On 07/08/2017 16:49, Fabrice Bacchella wrote:
Le 7 août 2017 à 17:41, FERNANDO FREDIANI <fernando.frediani@upx.com <mailto:fernando.frediani@upx.com>> a écrit :
Yet another downside of having a RAID (specially RAID 5 or 6) is that it reduces considerably the write speeds as each group of disks will end up having the write speed of a single disk as all other disks of that group have to wait for each other to write as well.
That's not true if you have medium to high range hardware raid. For example, HP Smart Array come with a flash cache of about 1 or 2 Gb that hides that from the OS.
--------------2B4B839116333F84136665DD Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body bgcolor="#FFFFFF" text="#000000"> <p>What you mentioned is a specific case and not a generic situation. The main point there is that RAID 5 or 6 impacts write performance compared when you write to only 2 given disks at a time. That was the comparison made.<br> </p> <p>Fernando<br> </p> <br> <div class="moz-cite-prefix">On 07/08/2017 16:49, Fabrice Bacchella wrote:<br> </div> <blockquote type="cite" cite="mid:034E384B-4B32-4FBC-A760-404EB38EBC86@orange.fr"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <br class=""> <div> <blockquote type="cite" class=""> <div class="">Le 7 août 2017 à 17:41, FERNANDO FREDIANI <<a href="mailto:fernando.frediani@upx.com" class="" moz-do-not-send="true">fernando.frediani@upx.com</a>> a écrit :</div> <br class="Apple-interchange-newline"> </blockquote> <br class=""> <blockquote type="cite" class=""> <div class=""> <p style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255);" class="">Yet another downside of having a RAID (specially RAID 5 or 6) is that it reduces considerably the write speeds as each group of disks will end up having the write speed of a single disk as all other disks of that group have to wait for each other to write as well.<br class=""> </p> </div> </blockquote> <br class=""> </div> That's not true if you have medium to high range hardware raid. For example, HP Smart Array come with a flash cache of about 1 or 2 Gb that hides that from the OS. </blockquote> <br> </body> </html> --------------2B4B839116333F84136665DD--