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sata raid0 vs 1 raptor
- Thread starter eddie500
- Start date
hulksterjoe
older and wiser now
- Joined
- Jan 1, 2001
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- 2,900
read performances will be close but writes take longer in raid 1
Originally posted by hulksterjoe
read performances will be close but writes take longer in raid 1
Are you saying writes take longer in raid 0, vs not having raid at all, forget about the raptor here say just the sata 7200 hard drives.
gigglebyte
2[H]4U
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- Jan 18, 2001
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- 3,814
Originally posted by hulksterjoe
read performances will be close but writes take longer in raid 1
the question was:
What faster (2) 7200 SATA HD in raid 0, or (1) 74gig raptor?
not RAID 0 or 1 but aside from that point why would it take longer in RAID 1? yes it has to write to a second disk but doesn't it do it at the same time or is there a delay?
a RAID 0 should be noticeably faster than a stand alone drive since you have more bandwidth/data when using RAID since it splits it up across 2 or more drives
hulksterjoe
older and wiser now
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- Jan 1, 2001
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Sorry I missed that little part about 1 drive.. I read it as which would give the better performance. heres a big quote
http://www.ahinc.com/raid.htm
RAID 0 uses a method of writing to the disks called striping. Let's assume you have a server with three drives of 500 MB, 1 GB and 2 GB. Normally a server would treat each of these drives individually. By incorporating striping, the system would see all of the drives as only one drive for a total of 3.5 GB. Big deal, you say. Wait, there's more.
When the system writes data to the disk, the RAID 0 striping kicks in and automatically distributes the data across all three drives. Part of a file (chunks of data) will be written to the first drive, the next part to the second drive, the next part to the third drive and then it starts all over again until the entire contents of the file have been written.
What this does is greatly increase the speed of the reading/writing process. If you have two drives on your server, it increases the speed by about 25%. If you have three drives, it increases the speed about 33%. When you consider that the main task a server is performing is reading and writing data, any increase in speed is highly welcome.
Besides increasing speed, the other benefit is that the drives can be of different sizes.
Because RAID 0 only writes the data once, it does not achieve data redundancy. If one of the drives fails, the entire system has to be restored because all files are split or striped across all drives.
Because there is no data redundancy, there is no loss of disk space.
RAID 1
RAID 1 uses a technology called mirroring or disk shadowing. RAID 1 requires a minimum of two drives that are exactly the same size. Every time a write is executed the same data is written to both drives, i.e. a mirror image. Well, almost a mirror image. The data is not reversed in the same way as when you look in the mirror.
So what you achieve with RAID 1 is data redundancy. If one of the drives fails, the system can continue to run by just writing to one drive. If you have hot swappable drives, you could pull out the bad drive, plug in a new one and the system is back to its normal state. How efficient and easy it is to execute all of this depends on the RAID controller and/or software that is being used.
The disadvantage of RAID 1 is that you loose half of your disk capacity. If you have two 4 GB drives, you don't have a total of 8 GB of space, but only 4 GB. So you are losing half of the capacity of disk space that you paid for. But on the other hand disk drives are fairly inexpensive today. What has to be considered, is what is the cost of downtime if a drive fails on your server. The downtime cost is probably much more than the cost of the additional drive.
Another slight disadvantage is that writing data will result in a slight decrease in performance, as the same data is written twice. But the offset for this is that the reading of data will realize an increase in speed. Basically the slower writing and faster reading offset each other.
So I guess my answer to your original question should be it depends if the raid gives you a 25% advantage then in theory I'd guess that that would make up for the 10K speed and even the playing field, but that being said I'd guess that over time that as you add more data to the single drive it'll take longer to pull off then the raid 1. so my vote is for raid 1 over time
http://www.ahinc.com/raid.htm
RAID 0 uses a method of writing to the disks called striping. Let's assume you have a server with three drives of 500 MB, 1 GB and 2 GB. Normally a server would treat each of these drives individually. By incorporating striping, the system would see all of the drives as only one drive for a total of 3.5 GB. Big deal, you say. Wait, there's more.
When the system writes data to the disk, the RAID 0 striping kicks in and automatically distributes the data across all three drives. Part of a file (chunks of data) will be written to the first drive, the next part to the second drive, the next part to the third drive and then it starts all over again until the entire contents of the file have been written.
What this does is greatly increase the speed of the reading/writing process. If you have two drives on your server, it increases the speed by about 25%. If you have three drives, it increases the speed about 33%. When you consider that the main task a server is performing is reading and writing data, any increase in speed is highly welcome.
Besides increasing speed, the other benefit is that the drives can be of different sizes.
Because RAID 0 only writes the data once, it does not achieve data redundancy. If one of the drives fails, the entire system has to be restored because all files are split or striped across all drives.
Because there is no data redundancy, there is no loss of disk space.
RAID 1
RAID 1 uses a technology called mirroring or disk shadowing. RAID 1 requires a minimum of two drives that are exactly the same size. Every time a write is executed the same data is written to both drives, i.e. a mirror image. Well, almost a mirror image. The data is not reversed in the same way as when you look in the mirror.
So what you achieve with RAID 1 is data redundancy. If one of the drives fails, the system can continue to run by just writing to one drive. If you have hot swappable drives, you could pull out the bad drive, plug in a new one and the system is back to its normal state. How efficient and easy it is to execute all of this depends on the RAID controller and/or software that is being used.
The disadvantage of RAID 1 is that you loose half of your disk capacity. If you have two 4 GB drives, you don't have a total of 8 GB of space, but only 4 GB. So you are losing half of the capacity of disk space that you paid for. But on the other hand disk drives are fairly inexpensive today. What has to be considered, is what is the cost of downtime if a drive fails on your server. The downtime cost is probably much more than the cost of the additional drive.
Another slight disadvantage is that writing data will result in a slight decrease in performance, as the same data is written twice. But the offset for this is that the reading of data will realize an increase in speed. Basically the slower writing and faster reading offset each other.
So I guess my answer to your original question should be it depends if the raid gives you a 25% advantage then in theory I'd guess that that would make up for the 10K speed and even the playing field, but that being said I'd guess that over time that as you add more data to the single drive it'll take longer to pull off then the raid 1. so my vote is for raid 1 over time