Stripe size on 7133-D40 RAID 1+0?

Stripe size on 7133-D40 RAID 1+0?

Post by aaa » Sat, 15 Jun 2002 21:06:09



We plan to install 7133-D40 to our P660 server (AIX 4.3.3).  The SSA D40
will configure as RAID 1+0 (14 (7-7) HD + 2 Hot spare).  This SSA is for
Informix database to use.  The database use 2GB Raw LVs.  my question are>

 1. does RAID 1+0 better than RAID 5 on database?

2. if one hard disk bad, is it easy to replace?  Can I hot swap and system
automatic mirror it back?  Anyone has procedure on this?

3. what kind of strip size is better (16k, 32K or 64k)?

 
 
 

Stripe size on 7133-D40 RAID 1+0?

Post by Joerg Brueh » Sat, 15 Jun 2002 23:59:45


Hi Anonymous!


> We plan to install 7133-D40 to our P660 server (AIX 4.3.3).  The SSA D40
> will configure as RAID 1+0 (14 (7-7) HD + 2 Hot spare).  This SSA is for
> Informix database to use.  The database use 2GB Raw LVs.  my question are>

>  1. does RAID 1+0 better than RAID 5 on database?

From all I read, RAID 5 is the slowest thing existing.
If any critical path (in a DBMS: typically log I/O) contains
I/O to RAID 5, performance will go down.

Also, do you expect striping to improve DBMS performance?
I can not speak about/for Informix, but AFAIK random I/O
(as opposed to sequential) does not profit from striping.
For our SQL DBMS ("Adabas D"), striping will do neither good
nor bad in most circumstances, but it adds a level of complexity
and mapping (no 1-to-1 correspondence between logical names
and physical entities) which I prefer to avoid.

Also, is Informix limited to 2 GB raw LVs? Again for reasons
of clarity (which makes administration easier), I propose
raw LVs that cover whole PVs (disks) if possible.

So my recommendation is:
- For the logs, use plain mirroring (RAID-1 or DBMS configuration,
  including "dual logs" if offered by Informix).
- For the data areas, RAID-5 may be considered, but expect it
  to reduce performance.

Quote:

> 2. if one hard disk bad, is it easy to replace?  Can I hot swap and system
> automatic mirror it back?  Anyone has procedure on this?

No comments of mine - no experience.

Quote:

> 3. what kind of strip size is better (16k, 32K or 64k)?

Here, we might discuss "strip_e"s but not "strip"s.
For a DBMS, I doubt any positive effect.

Regards,
Joerg Bruehe

--
Joerg Bruehe, SQL Datenbanksysteme GmbH, Berlin, Germany
     (speaking only for himself)


 
 
 

Stripe size on 7133-D40 RAID 1+0?

Post by Friedhelm Neye » Sun, 16 Jun 2002 01:50:39



> We plan to install 7133-D40 to our P660 server (AIX 4.3.3).  The SSA D40
> will configure as RAID 1+0 (14 (7-7) HD + 2 Hot spare).  This SSA is for
> Informix database to use.  The database use 2GB Raw LVs.  my question are>

>  1. does RAID 1+0 better than RAID 5 on database?

> 2. if one hard disk bad, is it easy to replace?  Can I hot swap and system
> automatic mirror it back?  Anyone has procedure on this?

No experience with RAID 1+0, but with RAID 5 it is easy. We have a RAID 5 (7+1
parity)
and if a diosk is down, we only change it and it will be mirrored by system
after a while
Quote:

> 3. what kind of strip size is better (16k, 32K or 64k)?

 
 
 

Stripe size on 7133-D40 RAID 1+0?

Post by RaNm » Mon, 01 Jul 2002 06:50:39


Stripe Size depends on application type using disk space... for Oracle
datafiles, 64K is the best value.

--
Vincent Jamart
UNIX/Oracle System Engineer
Systemat Computers Luxembourg S.A.



> > We plan to install 7133-D40 to our P660 server (AIX 4.3.3).  The SSA D40
> > will configure as RAID 1+0 (14 (7-7) HD + 2 Hot spare).  This SSA is for
> > Informix database to use.  The database use 2GB Raw LVs.  my question are>

> >  1. does RAID 1+0 better than RAID 5 on database?

> > 2. if one hard disk bad, is it easy to replace?  Can I hot swap and system
> > automatic mirror it back?  Anyone has procedure on this?

> No experience with RAID 1+0, but with RAID 5 it is easy. We have a RAID 5 (7+1
> parity)
> and if a diosk is down, we only change it and it will be mirrored by system
> after a while

> > 3. what kind of strip size is better (16k, 32K or 64k)?

 
 
 

1. Getting original shipping carton for 7133-D40

We have a need to send a 7133-D40 SSA drawer to another of our sites;
we also want to keep it in good shape and must use an original carton
in order to be insured by the shipper *and* to be covered by IBM warranty
along with using their preferred shipper. No problem.

Only catch is, we don't still have the original shipping carton.

Does anyone know where I'd want to even begin looking for one? Does
IBM sell these, or is it possible to get an unused one somewhere?

-Dan

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6. contab - most likely a newbie question!

7. Plan to have Two Servers each attached to the same two 7133-D40 using 6230 adapters

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9. IBM 7133-D40 with 8518/8218

10. Multiple pdisks ... same 7133-D40 slot address