I need help with a question.

districtfelon · 04-02-2008, 03:36 PM

Given a set of Seagate hard disks, 7200.9 ST-3250624AS, direct-attached to a server, what is the theoretical effective bandwidth of each of the following RAID organizations?

1)4-disk concatenated JBOD
2)4-disk RAID0
3)4-disk RAID1
4)4-disk RAID5
5)8-disk RAID5
6)18-disk RAID50, comprised of three 6-disk RAID5

i'd appreciate it if anyone can help me out.

**Cromewell** · 04-02-2008, 03:59 PM

For striped arrays, this is assuming ideal conditions (aka fake)

1. Single disk bandwidth.
2. 4x bandwidth of a single disk.
3. Single disk bandwidth
4. A 4 disk RAID5 of raptors scored ~140MB/s (h2benchw) so I would say some 7200.9s would be a bit slower 120MB/s maybe.
5. Ballpark 200MB/s (again raptors got 235 in h2benchw)
6. Hell if I know. If I had to guess, I would say it would be comparable to to 6 disk raid 5

districtfelon · 04-02-2008, 04:20 PM

ok so when I look up the seagate it says its "Host Transfer Rate" is 300 MB/s so when you say single disk bandwidth, do you mean its 300MB/s? and for the second part when you say 4xthe single bandwidth you mean 1200MB/s?

**Cromewell** · 04-03-2008, 01:35 AM

No a single disk's sustained bandwidth is give or take 55MB/s.

04-02-2008, 03:36 PM	#1 (permalink)
districtfelon New Member Join Date: Apr 2008 Posts: 2	I need help with a question. Given a set of Seagate hard disks, 7200.9 ST-3250624AS, direct-attached to a server, what is the theoretical effective bandwidth of each of the following RAID organizations? 1)4-disk concatenated JBOD 2)4-disk RAID0 3)4-disk RAID1 4)4-disk RAID5 5)8-disk RAID5 6)18-disk RAID50, comprised of three 6-disk RAID5 i'd appreciate it if anyone can help me out.

04-02-2008, 03:59 PM	#2 (permalink)
Cromewell Moderator Join Date: Dec 2004 Location: Canada Age: 24 Posts: 10,086	For striped arrays, this is assuming ideal conditions (aka fake) 1. Single disk bandwidth. 2. 4x bandwidth of a single disk. 3. Single disk bandwidth 4. A 4 disk RAID5 of raptors scored ~140MB/s (h2benchw) so I would say some 7200.9s would be a bit slower 120MB/s maybe. 5. Ballpark 200MB/s (again raptors got 235 in h2benchw) 6. Hell if I know. If I had to guess, I would say it would be comparable to to 6 disk raid 5 __________________ You know what the chain of command is? It's the chain I go get and beat you with 'til ya understand who's in ruttin' command here. I must plug a couple comics because they are good :D: www.ctrlaltdel-online.com www.userfriendly.org

04-03-2008, 01:35 AM	#4 (permalink)
Cromewell Moderator Join Date: Dec 2004 Location: Canada Age: 24 Posts: 10,086	No a single disk's sustained bandwidth is give or take 55MB/s. __________________ You know what the chain of command is? It's the chain I go get and beat you with 'til ya understand who's in ruttin' command here. I must plug a couple comics because they are good :D: www.ctrlaltdel-online.com www.userfriendly.org

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04-02-2008, 04:20 PM	#3 (permalink)
districtfelon New Member Join Date: Apr 2008 Posts: 2	ok so when I look up the seagate it says its "Host Transfer Rate" is 300 MB/s so when you say single disk bandwidth, do you mean its 300MB/s? and for the second part when you say 4xthe single bandwidth you mean 1200MB/s?