Discussion:
Setup of four 15k SAS disk with LSI raid controller
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Niels Kristian Schjødt
2013-03-13 17:43:16 UTC
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I have a server with 32GB ram, one intel E3-1245 and four 15k SAS disks with a BB LSI MegaRaid controller. I wan't the optimal performance for my server, which will be pretty write heavy at times, and less optimized for redundancy, as my data is not very crucial and I will be running a streaming replication along side.

Now what would you prefer:

1) 3 disks in RAID 0 containing PGDATA + 1 containing SYSTEM and WAL
2) All four in RAID 10 containing both PGDATA, SYSTEM AND WAL
3) 2 disks in RAID 1 containing PGDATA + 2 disks in RAID 1 containing SYSTEM and WAL
4) Something different?
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Vasilis Ventirozos
2013-03-13 18:15:25 UTC
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raid0 tends to linear scaling so 3 of them should give something close to
300% increased write speed. So i would say 1. but make sure you test your
configuration as soon as you can with bonnie++ or something similar

On Wed, Mar 13, 2013 at 7:43 PM, Niels Kristian Schjødt <
Post by Niels Kristian Schjødt
I have a server with 32GB ram, one intel E3-1245 and four 15k SAS disks
with a BB LSI MegaRaid controller. I wan't the optimal performance for my
server, which will be pretty write heavy at times, and less optimized for
redundancy, as my data is not very crucial and I will be running a
streaming replication along side.
1) 3 disks in RAID 0 containing PGDATA + 1 containing SYSTEM and WAL
2) All four in RAID 10 containing both PGDATA, SYSTEM AND WAL
3) 2 disks in RAID 1 containing PGDATA + 2 disks in RAID 1 containing SYSTEM and WAL
4) Something different?
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Niels Kristian Schjødt
2013-03-13 18:37:40 UTC
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raid0 tends to linear scaling so 3 of them should give something close to 300% increased write speed. So i would say 1. but make sure you test your configuration as soon as you can with bonnie++ or something similar
I have a server with 32GB ram, one intel E3-1245 and four 15k SAS disks with a BB LSI MegaRaid controller. I wan't the optimal performance for my server, which will be pretty write heavy at times, and less optimized for redundancy, as my data is not very crucial and I will be running a streaming replication along side.
1) 3 disks in RAID 0 containing PGDATA + 1 containing SYSTEM and WAL
2) All four in RAID 10 containing both PGDATA, SYSTEM AND WAL
3) 2 disks in RAID 1 containing PGDATA + 2 disks in RAID 1 containing SYSTEM and WAL
4) Something different?
A 5. option could also be to simply have all 4 disk in a RAID 0 containing all PGDATA, SYSTEM and WAL
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Vasilis Ventirozos
2013-03-13 18:45:40 UTC
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Its better to split WAL segments and data just because these two have
different io requirements and because its easier to measure and tune things
if you have them on different disks.

Vasilis Ventirozos

On Wed, Mar 13, 2013 at 8:37 PM, Niels Kristian Schjødt <
Post by Vasilis Ventirozos
raid0 tends to linear scaling so 3 of them should give something close to
300% increased write speed. So i would say 1. but make sure you test your
configuration as soon as you can with bonnie++ or something similar
On Wed, Mar 13, 2013 at 7:43 PM, Niels Kristian Schjødt <
Post by Niels Kristian Schjødt
I have a server with 32GB ram, one intel E3-1245 and four 15k SAS disks
with a BB LSI MegaRaid controller. I wan't the optimal performance for my
server, which will be pretty write heavy at times, and less optimized for
redundancy, as my data is not very crucial and I will be running a
streaming replication along side.
1) 3 disks in RAID 0 containing PGDATA + 1 containing SYSTEM and WAL
2) All four in RAID 10 containing both PGDATA, SYSTEM AND WAL
3) 2 disks in RAID 1 containing PGDATA + 2 disks in RAID 1 containing SYSTEM and WAL
4) Something different?
A 5. option could also be to simply have all 4 disk in a RAID 0 containing
all PGDATA, SYSTEM and WAL
Post by Niels Kristian Schjødt
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Joshua D. Drake
2013-03-13 19:01:11 UTC
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Post by Vasilis Ventirozos
Its better to split WAL segments and data just because these two have
different io requirements and because its easier to measure and tune
things if you have them on different disks.
Generally speaking you are correct but we are talking about RAID 0 here.

JD
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Niels Kristian Schjødt
2013-03-13 19:26:46 UTC
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Post by Joshua D. Drake
Post by Vasilis Ventirozos
Its better to split WAL segments and data just because these two have
different io requirements and because its easier to measure and tune
things if you have them on different disks.
Generally speaking you are correct but we are talking about RAID 0 here.
So your suggestion is?
Post by Joshua D. Drake
JD
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