I drool just reading your email about your servers! lol<br><br><div class="gmail_quote">On Feb 16, 2008 11:00 AM, Marc <<a href="mailto:drayson@net1plus.com">drayson@net1plus.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div><div></div><div class="Wj3C7c">Markus Schulz wrote:<br>> Am Freitag, 15. Februar 2008 schrieb Marc:<br>> [...]<br>>> Don't assume people on this list are experts. Some are, some are<br>>> informed users who have done research, some just make assumptions<br>
>> based off of one post or one article they read.<br>>>r severs<br>>> >From a statistical standpoint..<br>>><br>>> Raid0 would be the fastest, it is common sense. Your speed for any<br>>> action would be dependent on the number of drives you had or N.<br>
>> However if one drive fails you lose all data.<br>>><br>>> Raid3 or 5 would be the second fastest and would be safer due to the<br>>> ability to continue working without loss of data if you had a single<br>
>> drive fail. The difference between these 2 raid types is the way they<br>>> setup parity. Raid3 has a dedicated parity drive. Raid5 spreads<br>>> parity across all the drives.<br>>> Speed of any action on either of these raid configs would be the<br>
>> number of drives you had minus 1 or N-1.<br>><br>> sorry but thats not true. Show me a raid5 with 5-6 drives which will got<br>>> 300MB/s _write_ performance...<br>><br>> Fastest Raid _WITH_ redundancy was raid10.<br>
><br>><br><br>The high dollar hardware raid controllers will get close to the N-1 rate, I<br>have benchmarked them under sustained load, but the hardware raid are in the<br>$500-$1000 range, and raid10 with 6 disks will in a perfect world be<br>
180-210mb/second (3 effective drives-60-70mb/second/drive). RAID10 is<br>really<br>on the fasted RAID if you are benchmarking seek times (database), if you are<br><br>benchmarking raw sequential read and write rates with a good controller<br>
both are about the same speed with raid5/6 or with raid10, and even raid0<br>only gives a 10-20% gain over raid5/6. Raid10 only really wins when one<br>is doing a lot of seeks as small write seeks are expensive on raid5.<br>
<br>Most software raid has a problem that most of the older MB controllers and<br>cheaper controller cards really don't have independent channels and<br>interfere<br>with each other. On mine I get 70MB/second with one disk, and then it goes<br>
to 108mb/second with a second dd added and then to 115 with a 3rd, so the<br>controller is utter crap, but still I can get 40MB/second writes out of it<br>with raid5 and it is good enough. With the good controllers that goes<br>
70,140,<br>210,280 and I have tested good controllers and they do exist, one just has<br>to<br>be more careful in finding them, and a lot of the recent MB controllers are<br>good controllers.<br>_______________________________________________<br>
<br></div></div>I used to have a Raid10 for my video storage, but it filled up too quick.<br>I decided against switching to Raid0 due to not having any fault tolerance.<br>I saw Raid3/5 as the best option due to more storage space, like Raid0 but<br>
with FT.<br>Raid5 became my choice for this as we used it at work with great success. We<br>have servers with 2 (raid0), 6 (raid5), 16 (2x8 drives in raid5 then<br>striped), and 24 (3x8 drives in raid5 then striped) drive configurations.<br>
Each system except for the 2 drive server has 2 HDD mirrored for the OS and<br>the other drives are for media storage.<br>I drool over what I could do with these in a myth setup hehe.<br><div><div></div><div class="Wj3C7c">
<br><br>_______________________________________________<br>mythtv-users mailing list<br><a href="mailto:mythtv-users@mythtv.org">mythtv-users@mythtv.org</a><br><a href="http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users" target="_blank">http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</a><br>
</div></div></blockquote></div><br>