Re: [Declude.JunkMail] Raid Controller

[Matt]

Correction... "RAID 10 will do double a single drive plus a slight hit for mirroring and for striping" Matt Matt wrote: Not to beat a dead horse, but... Am I mistaken about on RAID 5 array with 4 disks out performing one RAID 10 array with 4 disks?  RAID 10 will do double RAID 0 plus a slight hit for mirroring.  I though RAID 5 with 4 disks would out perform two striped drives despite the overhead. There is another issue though.  I can only get 10 drive in a packed 3U chassis, so I could only do two RAID 10 arrays, but with RAID 50, drive partitions wouldn't matter if I'm not mistaken, 1 would be the same as 5 partitions, or close enough at least.  With 8 disks in RAID 10, I could only separate the disk I/O for two logical drives. Matt Keith Anderson wrote: Nah, RAID 10's performance will always be twice as fast as RAID 50. Look at the writes required: WRITE to RAID 10: Write data to primary stripe Copy to backup stripe WRITE to RAID 50: Write data to primary stripe Update the parity on primary stripe Copy data to secondary stripe Update the parity on secondary stripe READ from RAID 10: Read data from primary stripe (half of the drives) READ from RAID 50: Read data from primary and secondary stripes (all of the drives) The advantage of RAID 50 over RAID 10 is better economy of drive space. Consider six drives, all 100 gigabytes: RAID 10: Three drives for storage Three drives for backup Total usuable space = 300 gigs RAID 50: Two drives on each stripe used for storage One drive on each stripe used for parity Total usable space = 400 gigs If you applied RAID 50 to my stack here, with 24 total drives, you would get TONS more space, but performance would drop by 50%, which would suck, because my system is right on the 60% mark for the throughput of the stack. Keith I guess from my perspective I'm down to a choice of one thing, RAID 10 or RAID 50. I figure that I will build an 8 drive system, and I could either go with a 4 drive RAID 10 configuration with 2 each, or striped RAID 5 array. It seems that I would need 3 striped drives in RAID 10 (6 total) to get the performance of a RAID 50 implementation, however that's only for one drive of course. The advantage goes down as you dedicate functions to separate sets of drives in RAID 10. There's no equation that can tell you off the cuff what's best because it depends on the application and how many sequential reads and writes you are doing at one time and if those can be split up somewhat evenly across different drive letters. [AUTOMATED NOTE: Your mail server [63.147.33.8] is missing a reverse DNS entry. All Internet hosts are required to have a reverse DNS entry. The missing reverse DNS entry will cause your mail to be treated as spam on some servers, such as AOL.] --- [This E-mail was scanned for viruses by Declude Virus (http://www.declude.com)] --- This E-mail came from the Declude.JunkMail mailing list. To unsubscribe, just send an E-mail to [EMAIL PROTECTED], and type "unsubscribe Declude.JunkMail". The archives can be found at http://www.mail-archive.com. -- ===================================================== MailPure custom filters for Declude JunkMail Pro. http://www.mailpure.com/software/ ===================================================== -- ===================================================== MailPure custom filters for Declude JunkMail Pro. http://www.mailpure.com/software/ =====================================================