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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Sizing - RAC, storage subsystem EMC
Yes, RAID 5 would be ugly. Doesn't EMC use RAID-s though, which stores a copy of the parity on all drives. It was a while ago that I used EMC, so things may have changed, or more likely, my memory is warped....
Can anyone confirm this (no, not that my memory is warped, that has been confirmed plenty of times).
Mike Boligan
"Cary Millsap"
<cary.millsap_at_hot To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
sos.com> cc:
Sent by: Subject: RE: Sizing - RAC, storage subsystem EMC
root_at_fatcity.com
05/22/2003 12:42
PM
Please respond to
ORACLE-L
Oh man, ?One parity disk for 10?20 disks means that if *any* single disk in the group fails (which will happen five times more frequently in a 20-drive group than in a 4-drive group), then for the duration of the partial outage every single read from the failed disk is going to engage all 10?20 disks in the group. And the resynchronization of the new disk, once it's plugged in, is going to require the *full disk scan of all 10?20 devices*. I wouldn't want to be anywhere nearby when *that* happened.
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- Hotsos Clinic 101 in Reykjavik, Ottawa, Dallas, Washington, Denver, Sydney
Depends on how much cache you got and how many DB servers is the SAN serving.
Once your cache
is saturated by reads and writes, RAID 5 is going to hurt you.
-----Original Message-----
From: Yechiel Adar [mailto:adar76_at_inter.net.il]
Sent: Wednesday, May 21, 2003 8:55 AM
To: Multiple recipients of list ORACLE-L
Subject: Re: Sizing - RAC, storage subsystem EMC
With EMC, or any other SAN, you do not write to the disks. You write into
a cache memory on the controller and the controller then writes the data
to the disks at his own time. If you have big enough write cache on the
controller the raid-5 write speed does not concern you.
Raid-5 might be a little slow but it save almost 1/2 the disk space needed
to ensure the correctness of the data since it can use one parity disk for
10-20 disks.
Yechiel Adar
Mehish
----- Original Message -----
From: George.Leonard_at_za.didata.com
To: Multiple recipients of list ORACLE-L
Sent: Tuesday, May 20, 2003 9:06 AM
Subject: Sizing - RAC, storage subsystem EMC
Hi all, hope you can give some input ideas.
I am in the process of designing a system for a client of ours for a
proposal
The sizing information I have been given is as follows.
58.1 million tickets/day at 351 bytes per record. The record was complete
populated (all columns filled to max) in a table and then analyzed.
Average row size 351 bytes.
=~ 19 GB/day. Raw data. Plus overhead (indexes, temp space, rollback,
some other data etc) here and there I have requested 5 TB.
We need to keep records for a month. Table design I am looking at is a
date partition with a second level hash partition. This is so that I can
move data in the oldest week/table space off line and write them to
optical storage for possible retrieval at a later date (requirement).
Of course this will be on locally managed table spaces with auto storage
management for segments.
Hardware:
The database will be a Oracle RAC 9.2.0.4 on Sun cluster 3 build on 2 x
Sun StarFire V880, 4 CPU's, 4 GB RAM each,
Connected to an EMC SAN via Fiber Channel
I do not have more information about the EMC array at the moment. Hitachi
has been mentioned. (excuse the spelling)
Question I have.
I have been asked how many writes the Database will be doing to the SAN
per second.
I have determined that I should expect about 2000 tickets/second.
The table in question will have 2 indexes.
Now following rough guessing I said I should expect at least 16 000
writes/second
This was done by say/assuming
2 writes for the redo log files (2 members)
2 writes for the control files (2 control files)
2 writes to index blocks
1 write to undo table space block
1 write to table block for data
total 8 blocks written to per ticket.
Now I know the above is a real rough. And probably very wrong, if someone
can shed some more light on it and give me a more accurate method/guess I
would appreciate it.
Another question.
The hardware SAN engineers are telling me they want to configure the SAN
in a RAID 5 configuration. I have requested Raid 0 + 1. They say this is
going to be to expensive and the new technology allows them to give me
the performance I want using RAID 5.
I would prefer to err on the side of caution and follow Oracle industry
wide recommendation and follow the SAME methodology.
Comment.
Thx.
George
________________________________________________
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Michael Boligan INET: michael.boligan.b_at_bayer.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu May 22 2003 - 13:27:10 CDT
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