<html><head><style type='text/css'>p { margin: 0; }</style><style type='text/css'>body { font-family: 'Verdana'; font-size: 8pt; color: #000000}</style></head><body>my system is an AMD 64 X2 3800+ with 2 GB RAM.<br><br>I have 5 250 GB HDD in a software RAID5. 3 are on the local IDE control (yes, 2 drives share an IDE bus), and two are on an older Promise Controller. This is what I get for speeds:<br><br>mythbackend raid5 # dd if=/dev/zero of=testfile bs=1M count=16384<br>16384+0 records in<br>16384+0 records out<br>17179869184 bytes (17 GB) copied, 859.12 s, 20.0 MB/s<br>mythbackend raid5 # <br><br>Granted, the system is running a few virtual systems as well, but none of them hits the hard drive too hard.<br><br>Gerald<br><br>----- Original Message -----<br>From: "Markus Schulz" <msc@antzsystem.de><br>To: mythtv-users@mythtv.org<br>Sent: Saturday, February 16, 2008 9:38:33 AM (GMT-0600) America/Chicago<br>Subject: Re: [mythtv-users] Fastest RAID for HD?<br><br>Am Samstag, 16. Februar 2008 schrieb Roger Heflin:<br>> Markus Schulz wrote:<br>> > Am Freitag, 15. Februar 2008 schrieb Marc:<br>> > [...]<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>> >><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<br>> >> the ability to continue working without loss of data if you had a<br>> >> single drive fail. The difference between these 2 raid types is<br>> >> the way they setup parity. Raid3 has a dedicated parity drive.<br>> >> Raid5 spreads 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<br>> > will got<br>> ><br>> >> 300MB/s _write_ performance...<br>> ><br>> > Fastest Raid _WITH_ redundancy was raid10.<br>><br>> The high dollar hardware raid controllers will get close to the N-1<br>> rate, I have benchmarked them under sustained load, but the hardware<br>> raid are in the $500-$1000 range, and raid10 with 6 disks will in a<br>> perfect world be 180-210mb/second (3 effective<br>> drives-60-70mb/second/drive). <br><br>i've built a system two weeks ago with:<br><br>6 * 73Gb 15k 2.5" sas in a smart array p400 (512MB cache) for a HP dl380 <br>G5 system<br><br>d1:/mnt/disk2# dd if=/dev/zero of=testfile bs=1M count=16384<br>16384+0 Datensätze ein<br>16384+0 Datensätze aus<br>17179869184 Bytes (17 GB) kopiert, 55,6692 Sekunden, 309 MB/s<br><br>d1:/mnt/disk2# dd if=testfile of=/dev/null bs=1M<br>16384+0 Datensätze ein<br>16384+0 Datensätze aus<br>17179869184 Bytes (17 GB) kopiert, 56,1641 Sekunden, 306 MB/s<br><br>-- <br>Markus Schulz<br><br><br>__________________________________________<br>mythtv-users mailing list<br>mythtv-users@mythtv.org<br>http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users<br></body></html>