Re: [ovirt-users] Good practices
--_000_DB6P190MB0280AD888032AB4A6232D576C88A0DB6P190MB0280EURP_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ok, the 40Gb NIC that I got were for free. But anyway, if you were working = with 6 HDD + 1 SSD per server, then you get 21 disks on your cluster. As da= ta in a JBOD will be built all over the network, then it can be really inte= nsive especially depending on the number of replicas you choose for your ne= eds. Also, when moving a VM alive you must transfer the memory contents of = a VM to another node (just think about moving a VM with 32GB RAM). All toge= ther, it can be a quite large chunk of data moving over the network all the= time. While 40Gb NIC is not a "must", I think it is more affordable as it = cost much less then a good disk controller. But my confusion is that, as said by other fellows, the best "performance m= odel" is when you use a hardware RAIDed brick (i.e.: 5 or 6) to assemble yo= ur GlusterFS. In this case, as I would have to buy a good controller but ha= ve less network traffic, to lower the cost I would then use a separate netw= ork made of 10Gb NICs plus the controller. Moacir
Le 8 ao?t 2017 ? 04:08, FERNANDO FREDIANI <fernando.frediani@upx.com> a ?crit :
Even if you have a Hardware RAID Controller with Writeback cache you will have a significant performance penalty and may not fully use all the resources you mentioned you have.
Nope again,from my experience with HP Smart Array and write back cache, write, that goes in the cache, are even faster that read that must goes t=
o
the disks. of course if the write are too fast and to big, they will over overflow the cache. But on todays controller they are multi-gigabyte cach= e, you must write a lot to fill them. And if you can afford 40Gb card, you c= an afford decent controller.
The last sentence raises an excellent point: balance your resources. Don't spend a fortune on one component while another will end up being your bottleneck. Storage is usually the slowest link in the chain. I personally believe that spending the money on NVMe drives makes more sense than 40Gb (except [1], which is suspiciously cheap!) Y. [1] http://a.co/4hsCTqG --_000_DB6P190MB0280AD888032AB4A6232D576C88A0DB6P190MB0280EURP_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <html> <head> <meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Diso-8859-= 1"> <style type=3D"text/css" style=3D"display:none;"><!-- P {margin-top:0;margi= n-bottom:0;} --></style> </head> <body dir=3D"ltr"> <div id=3D"divtagdefaultwrapper" style=3D"font-size:12pt;color:#000000;font= -family:Calibri,Helvetica,sans-serif;" dir=3D"ltr"> <p>Ok, the 40Gb NIC that I got were for free. But anyway, if you were worki= ng with 6 HDD + 1 SSD per server, then you get 21 disks on your cluster= . As data in a JBOD will be built all over the network, then it can be real= ly intensive especially depending on the number of replicas you choose for your needs. Also, when moving a VM a= live you must transfer the memory contents of a VM to another node (just th= ink about moving a VM with 32GB RAM). All together, it can be a quite large= chunk of data moving over the network all the time. While 40Gb NIC is not a "must", I think it is more= affordable as it cost much less then a good disk controller.</p> <p><br> </p> <p>But my confusion is that, as said by other fellows, the best "perfo= rmance model" is when you use a hardware RAIDed brick (i.e.: 5 or 6) t= o assemble your GlusterFS. In this case, as I would have to buy a good cont= roller but have less network traffic, to lower the cost I would then use a separate network made of 10Gb NICs plus the co= ntroller.</p> <p><br> </p> <p>Moacir<br> </p> <div style=3D"color: rgb(49, 55, 57);"><font size=3D"2"><span style=3D"font= -size:10pt;"> <div class=3D"PlainText"><br> <br> <br> ><br> > > Le 8 ao?t 2017 ? 04:08, FERNANDO FREDIANI <fernando.frediani@u= px.com> a<br> > ?crit :<br> ><br> > > Even if you have a Hardware RAID Controller with Writeback cache = you<br> > will have a significant performance penalty and may not fully use all = the<br> > resources you mentioned you have.<br> > ><br> ><br> > Nope again,from my experience with HP Smart Array and write back cache= ,<br> > write, that goes in the cache, are even faster that read that must goe= s to<br> > the disks. of course if the write are too fast and to big, they will o= ver<br> > overflow the cache. But on todays controller they are multi-gigabyte c= ache,<br> > you must write a lot to fill them. And if you can afford 40Gb card, yo= u can<br> > afford decent controller.<br> ><br> <br> The last sentence raises an excellent point: balance your resources. Don't<= br> spend a fortune on one component while another will end up being your<br> bottleneck.<br> Storage is usually the slowest link in the chain. I personally believe that= <br> spending the money on NVMe drives makes more sense than 40Gb (except [1],<b= r> which is suspiciously cheap!)<br> <br> Y.<br> [1] <a href=3D"http://a.co/4hsCTqG" id=3D"LPlnk802834" previewremoved=3D"tr= ue">http://a.co/4hsCTqG</a><br> <br> </div> </span></font></div> </div> </body> </html> --_000_DB6P190MB0280AD888032AB4A6232D576C88A0DB6P190MB0280EURP_--
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Moacir Ferreira