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Posted: Fri Mar 30, 2007 6:19 pm
by Memo
I have :
8 Seagate Cheetah 15k 73gb hdds
1 Adaptec 3805 RAID 8ch SAS controller.
What would be faster:
two 4 drive raid 5s in stripe = raid50
or
one 7 drive raid 6 with a hot spare?
faster for reads, and faster for writes?
Is there another option for very fast random read and write ios?
I found ramsan, but they appear to be 30k
also found :
2 x HyperDrive4 Internal RAID System (0-32GB)
£2250 (+ VAT) $4390 (US)
does anyone have any good advice?
I need extream performance for under 5k.
Posted: Fri Mar 30, 2007 6:44 pm
by FlingPu
For extreme performance Raid 0 /tongue.gif" style="vertical-align:middle" emoid=":P" border="0" alt="tongue.gif" />
Between Raid 6 and Raid 50, I would choose Raid 50 for greater read/write speed, and Raid 6 for reliability and ease of hot swapping.
Posted: Fri Mar 30, 2007 6:47 pm
by Memo
Do you know any good benchmark sites that compair raid speeds with cards?
I'm not quite as concerned about very high sustaned transfer speeds. It's much more important for IOPS.
Its for a Postgre server.
Posted: Fri Mar 30, 2007 7:22 pm
by Malicious Wraith
FlingPu wrote:QUOTE (FlingPu @ Mar 30 2007, 10:44 AM) For extreme performance Raid 0 /tongue.gif" style="vertical-align:middle" emoid=":P" border="0" alt="tongue.gif" />
Between Raid 6 and Raid 50, I would choose Raid 50 for greater read/write speed, and Raid 6 for reliability and ease of hot swapping.
Qft, I have 2 10000x RPM Hard Drives running in raid 0.
Its *quick* as hell.
Posted: Fri Mar 30, 2007 7:33 pm
by pkk
RAID50 (2 RAID5 arrays connected via RAID 0) is the fastest, one disk each segment can fall out without problems.
RAID6 is more secure, two disks can fall out at once.
I would choose RAID 50, it's secure enought.
Posted: Fri Mar 30, 2007 7:35 pm
by Memo
ok so we have eliminated raid6 in favor of 50.
now what about 50 vs 10 or 0+1?
Posted: Fri Mar 30, 2007 8:19 pm
by FlingPu
Posted: Fri Mar 30, 2007 11:12 pm
by Anguirel
Posted: Fri Mar 30, 2007 11:19 pm
by aarmstrong
RAID 50 has too much overhead (processing and diskspace) for my tastes. I use RAID 10 almost exclusively (even over RAID5). It's very simple, redundant, and fast - it blows RAID 50 out of the water and you'll gain an extra 73GB of space in your configuration.
Posted: Sun Apr 01, 2007 5:51 pm
by D-boy
aarmstrong wrote:QUOTE (aarmstrong @ Mar 30 2007, 07:19 PM) RAID 50 has too much overhead (processing and diskspace) for my tastes. I use RAID 10 almost exclusively (even over RAID5). It's very simple, redundant, and fast - it blows RAID 50 out of the water and you'll gain an extra 73GB of space in your configuration.
73GB more than what? By my math:
RAID 10:
( (4 x 73GB) + (4 x 73GB) ) / 2 = 292GB
RAID 50:
( (4-1) * 73GB) + ( (4-1) * 73GB) = 438GB
They offer the same protection, so you trade performance for capacity.
If you need extreme performance, go RAID 10.
If you have a drive that has a high failure rate, RAID 6 is the best as any two drives can fail.