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zieloo
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 Posted: Wed Jun 15, 2005 3:25 pm Post subject: [CLOSED] raid slower than normally partitioned disk? |
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Just a quick question:
I'm aware of the fact that raid uses CPU and under rather heavy load the performance may be worse but is it possible that raided disks reads data 20-50% slower than non-raid ones? Checked it with hdparm which, I know, it's not a benchmark tool, but the same is being reported by bonnie, for instance.
Last edited by zieloo on Fri Jun 17, 2005 9:28 am; edited 1 time in total |
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nevynxxx
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| Posted: Wed Jun 15, 2005 3:41 pm Post subject: |
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Depends on the type of RAID.
Hardware or software?
What configuration?
Hardware raid 1 should be the same speed as a single disk, hardware raid 0 should be almost twice as fast, as should raid 0+1 in hardware.
Software raid will depend on the spec of the rest of the comp.
I notice on your spec you have 4 drives in raid 0 array, that should be almost 4 times as fast as the single disks, if it is hardware raid.
you do know that if any drive fails you wil have hell recovering data though don't you?
http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel0-c.html
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zieloo
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| Posted: Wed Jun 15, 2005 5:11 pm Post subject: |
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| nevynxxx wrote: | Depends on the type of RAID.
Hardware or software?
What configuration?
Hardware raid 1 should be the same speed as a single disk, hardware raid 0 should be almost twice as fast, as should raid 0+1 in hardware.
Software raid will depend on the spec of the rest of the comp.
I notice on your spec you have 4 drives in raid 0 array, that should be almost 4 times as fast as the single disks, if it is hardware raid.
you do know that if any drive fails you wil have hell recovering data though don't you?
http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel0-c.html
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Software raid-0.
I do only have 2 drives in the raid array (switching step by step). It is in fact twice as fast as the single disk but only if comp is left idle.
Whenever I run a program or do sth that may affect either the disk or the CPU I can hardly see any performance gain.
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Recommended Uses: Non-critical data
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Sort of.
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(or data that changes infrequently and is backed up regularly)
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Backup Is A Must [tm].
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requiring high speed, particularly write speed, and low cost of implementation.
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All is true.
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Audio and video streaming and editing; web servers; graphic design; high-end gaming or hobbyist systems;
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Oh, yeah!;P
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temporary or "scratch" disks on larger machines.
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In a way yes...
Whatever the reasons os me setting up raid-0 were I know about the possible consequesces of hard disk fail. Thanks for your interest, anyway:) |
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nevynxxx
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| Posted: Thu Jun 16, 2005 7:57 am Post subject: |
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If it's a cacheless celeron, and a software raid, it will not give fantastic performance I wouldn't have thought (I have never tried this, others may have and give you more info), do they drives have onboard cache? That will also affect the performance.
If these are IDE cards why not just buy a raid card? They don't cost much (even compaired to the price of a hard disk) and they give such better performance it's untrue.
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zieloo
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| Posted: Thu Jun 16, 2005 9:23 am Post subject: |
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| nevynxxx wrote: | If it's a cacheless celeron, and a software raid, it will not give fantastic performance I wouldn't have thought (I have never tried this, others may have and give you more info), do they drives have onboard cache? That will also affect the performance.
If these are IDE cards why not just buy a raid card? They don't cost much (even compaired to the price of a hard disk) and they give such better performance it's untrue. |
Not really cacheless;)
I thought about buying an additional raid card (sata-raid?) but I want to try without, first. As I initially said I was just curious if that really can occur for a array to be slower than a regular disk, if so than gonna visit a local store;) |
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nevynxxx
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| Posted: Thu Jun 16, 2005 9:37 am Post subject: |
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Well like I said.
I don't know, because I have never done a software raid.
But the cost of an IDE or SATA raid card is just silly if you want to go that route.
If your drives are SATA I'd go for an SATAII controller, if they are IDE might as well stick with that, no point buying all new drives just yet.
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Chrystalsky
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| Posted: Thu Jun 16, 2005 3:22 pm Post subject: |
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long time ago (about 5 years on a RedHat-Box) i installed a software raid and it slowed the hole Server down.....
IDE-Raid is really cheap, about 20 $ @ ebay i guess....
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zieloo
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| Posted: Fri Jun 17, 2005 9:08 am Post subject: |
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| Chrystalsky wrote: | long time ago (about 5 years on a RedHat-Box) i installed a software raid and it slowed the hole Server down.....
IDE-Raid is really cheap, about 20 $ @ ebay i guess.... |
Thanks... Will give it a try:P |
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