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Gary Mills
Guest
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 Posted: Sat Jan 10, 2004 9:48 pm Post subject: How to improve disk performance? |
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I'm planning an upgrade for one of our servers. It's currently an
E450 with 4 400 MHz CPUs, 4 gigs of memory, and 8 18-gig internal
disks. The disks are mirrored with SDS, giving about 64 gigs of
usable space.
It's easy to find a new machine with more than double the aggregate
CPU speed, and more than double the memory, but how do I improve
disk performance? I need redundancy and high performance, but not
necessarily more disk space.
Let's say I wanted to double the disk performance? Are the internal
disks on a V880 that much faster than those on an E450? Would an
external RAID array be a better choice? What's available with low
capacity and high performance? Would a different filesystem than
UFS help? What's available for Solaris?
--
-Gary Mills- -Unix Support- -U of M Academic Computing and Networking- |
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Fredrik Lundholm
Guest
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| Posted: Sun Jan 11, 2004 12:17 am Post subject: Re: How to improve disk performance? |
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In article <btp6rr$7k9$1@canopus.cc.umanitoba.ca>,
Gary Mills <mills@cc.umanitoba.ca> wrote:
| Quote: | It's easy to find a new machine with more than double the aggregate
CPU speed, and more than double the memory, but how do I improve
disk performance? I need redundancy and high performance, but not
necessarily more disk space.
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Low cost with redundancy means SE3310. Higher performace and even better
redundancy means the SE3510.
| Quote: | Let's say I wanted to double the disk performance? Are the internal
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Very nice starting point.
| Quote: | disks on a V880 that much faster than those on an E450? Would an
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The disks in a V880 is apx the same performance as in a E450.
You really need an external raid controller to give you a large number of
spindles and good redundancy.
Example, in a V880 you have up to twelve disks. Two are mirrored for the OS.
Maybe you keep two extra for swap.
Because of the non existing raid controller you must mirror your data, and
still suffer high write latrency. Gives you 4 available disks.
Expensive and low performace compared to a nice RAID-array like a SE3510.
| Quote: | external RAID array be a better choice? What's available with low
capacity and high performance? Would a different filesystem than
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SE3510 with 36GB 15k RPM drives is a very capable solution
to which you can connect multiple 2Gbit cards and load balance from
within Solaris. (no extra charge)
| Quote: | UFS help? What's available for Solaris?
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UFS is usually good enough. More disks are probably a more cost effective
upgrade should you need extra performance.
Anyway, a V880 connected to a SE3510 is a very nice combination.
/wfr
Fredrik
--
Fredrik Lundholm
dol @ ce.chalmers.se |
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Gary Mills
Guest
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| Posted: Sun Jan 11, 2004 12:30 am Post subject: Re: How to improve disk performance? |
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In <btpfk2$fup$1@eol.dd.chalmers.se> dol@ce.chalmers.se (Fredrik Lundholm) writes:
| Quote: | In article <btp6rr$7k9$1@canopus.cc.umanitoba.ca>,
Gary Mills <mills@cc.umanitoba.ca> wrote:
Let's say I wanted to double the disk performance? Are the internal
Very nice starting point.
disks on a V880 that much faster than those on an E450? Would an
The disks in a V880 is apx the same performance as in a E450.
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That's what I suspected, even though the V880 disks are fibre channel.
| Quote: | You really need an external raid controller to give you a large number of
spindles and good redundancy.
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Yes, and the requirement for a large number of spindles means a lot of
unused capacity, with 36-gig disks being the smallest available these
days.
| Quote: | external RAID array be a better choice? What's available with low
capacity and high performance? Would a different filesystem than
SE3510 with 36GB 15k RPM drives is a very capable solution
to which you can connect multiple 2Gbit cards and load balance from
within Solaris. (no extra charge)
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That sounds attractive. I'll investigate.
| Quote: | Anyway, a V880 connected to a SE3510 is a very nice combination.
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Or, a V480, if 4 CPUs is all I need.
--
-Gary Mills- -Unix Support- -U of M Academic Computing and Networking- |
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Lars Tunkrans
Guest
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| Posted: Sun Jan 11, 2004 3:50 am Post subject: Re: How to improve disk performance? |
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mills@cc.umanitoba.ca (Gary Mills) wrote in message news:<btp6rr$7k9$1@canopus.cc.umanitoba.ca>...
| Quote: | I'm planning an upgrade for one of our servers. It's currently an
E450 with 4 400 MHz CPUs, 4 gigs of memory, and 8 18-gig internal
disks. The disks are mirrored with SDS, giving about 64 gigs of
usable space.
It's easy to find a new machine with more than double the aggregate
CPU speed, and more than double the memory, but how do I improve
disk performance? I need redundancy and high performance, but not
necessarily more disk space.
|
Seagate's advertising says that the 15K rpms drives gives you
35% more I/O's per second than the 10K rpm drives.
So if a typical 10K disk gives you 120 IOPS you should get about
170 IOPS from a 15K disk.
| Quote: |
Let's say I wanted to double the disk performance? Are the internal
disks on a V880 that much faster than those on an E450?
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As they are still 10K drives .. No their not "much faster"
They are a bit faster as the transfer rates has increased and
the access times has decreased somewhat in the 5 years that
passed since the heyday of the E450.
Would an
| Quote: | external RAID array be a better choice? What's available with low
capacity and high performance? Would a different filesystem than
UFS help? What's available for Solaris?
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As you are useing all the 5 SCSI channels on the 450 you have a
theroetical disk bandwith of 200 MB/s = 2 Gbit/s in your
present system, And 18 * 120 = 2160 IOPS.
2160 *2 = 4320
4320 / 170 = 25 15K rpm disks to double disk throughput.
The smallest 15K rpm disk is 36GB.
You will probably also need 4 Gbit/s bandwith
Cache in raid-arrays do two things well:
1) Repeted reads of the same data is offloaded from the disks.
2) Write operations are cached and aggregated before they are
written to disk. This is very useful for bursts of small
write operations.
The nature of your application will determine the amount of effect
a RAID Cache has on the throughput.
There is two remaing advantages that the veritas filesystem has
as compared to UFS.
1) It can do ON-LINE filesystem DE-fragmentation.
2) It is possible to preallocate space for a file and therefore
ensure that the file is written in physical consecutive
sectors on the disk.
//Lars |
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