Does software RAID take advantage of SMP, or 64 bit CPU(s)?
A few simple questions about the 2.6.16+ kernel and software RAID. Does software RAID in the 2.6.16 kernel take advantage of SMP? Does software RAID take advantage of 64-bit CPU(s)?
If there are any good web sites that cover this information, a link would be GREAT!
-Adam Talbot
Quoted 2 lines · On Monday May 22, [email protected] wrote:
A few simple questions about the 2.6.16+ kernel and software RAID. Does software RAID in the 2.6.16 kernel take advantage of SMP?
Not exactly. RAID5/6 tends to use just one cpu for parity calculations, but that frees up other cpus for doing other important work.
Quoted 1 line
Does software RAID take advantage of 64-bit CPU(s)?
No more or less that other code in the kernel. Sometimes using a 64-bit CPU is a cost because more data is shuffled around...
Was there some particular sort of 'advantage' that you were thinking of?
NeilBrown
Quoted 9 lines
If there are any good web sites that cover this information, a link would be GREAT!
(quoted diff) +0
-2-Adam Talbot -To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [email protected]
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-Neil
I was not looking for any direct advantage. It is more a money VS performance thing. I have a old dual proc Opteron motherboard. I am going with 64-bit, but it is much cheaper if I just go buy a nice single proc board instead of buying two Opterons for my dual proc board. If I could get a 1.5~2X performance improvement with SMP I would pay the extra money. If there is no major performance difference, I will take the cheap road.
Thank you for the good input.
-Adam
P.S. Here is my current plan.
RAID 6, 6X 400GB SATA 2.0 HDD's, Athlon FX 53, 1GB DDR 400, Nvidia based motherboard, Gb Ethernet. Storing 15,000+ MP3's, 500+ movies.
Quoted 40 lines · Neil Brown
Quoted 3 lines · On Monday May 22, [email protected] wrote:
A few simple questions about the 2.6.16+ kernel and software RAID. Does software RAID in the 2.6.16 kernel take advantage of SMP?
Not exactly. RAID5/6 tends to use just one cpu for parity calculations, but that frees up other cpus for doing other important work.
Quoted 2 lines
Does software RAID take advantage of 64-bit CPU(s)?
No more or less that other code in the kernel. Sometimes using a 64-bit CPU is a cost because more data is shuffled around...
Was there some particular sort of 'advantage' that you were thinking of?
NeilBrown
Quoted 10 lines
If there are any good web sites that cover this information, a link would be GREAT!
(quoted diff) +0
-2-Adam Talbot -To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html-
To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
On 23 May 2006, Neil Brown noted:
Quoted 7 lines · On Monday May 22, [email protected] wrote:
Quoted 2 lines
A few simple questions about the 2.6.16+ kernel and software RAID. Does software RAID in the 2.6.16 kernel take advantage of SMP?
Not exactly. RAID5/6 tends to use just one cpu for parity calculations, but that frees up other cpus for doing other important work.
To expand on this, that depends on how many RAID arrays you've got, since there's one parity-computation daemon per array.
If you have several arrays and are writing to them at the same time, or several arrays and some are degraded, then several md*_raid* daemons might be working at once.
But that's not very likely, I'd guess. (I have multiple RAID-5 arrays, but that's only because I'm trying to get useful RAIDing on multiple disks of drastically different size.)
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