My question:
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Managers!
We're starting to build the raid 5 arrays on our 4000.
The drives are arranged 3 drives per channel using a kzpac controller.
The drives are 3 drives in two enclosures.
(We have three other drives that are not on that controller in another
enclosure.)
Ideally we wanted to define a logical drive using all six drives.
However the largest logical drive we can define is one with four drives.
The config utility says that we should be able to build a raid 5 array
with 3 t o 8 disks. But apparently the fact that we're using 2 channels
or the size of the drives(they're all 9.1GB) prevents us from defining
all six as one.
What we've done is make two logical drives with 3 drives each.
The config looks this way:
chan 0 chan 1
drives: a0 a1
b0 a2
b1 b2
And we're going to try to combine all six with LSM later if that's doable.
But my question is why can't we combine six at the outset?
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I received answers from:
daiken_at_regents.edu
Mervyn.Weis_at_digital.com
mjwatson_at_snafu.livemet.net
alan_at_nabeth.cxo.dec.com
webster_at_ssdpdc.lgb.cal.boeing.com
The most complete answer came from Mervyn Weis:
Karen,
It is my understanding that the largest logical drive that can be built on a
RAID Controller of that nature is 32GB. 4 x 9.1GB drives in a RAID 5
configuration means that only 3 X 9.1GB drives are actually usable. This
adds up to approx. 27GB which is fine and which is why it is accepted by the
system. If you are using AdvFS, you might want to make 2 logical drives of
this size and then use the addvol command to combine them into a single
domain. If you are using UFS File Systems, you might have no choice but to
use LSM. This issue has been discussed before within this list; perhaps a
search of the archives will clarify it for you and lead you into some other
explanations and solutions.
Hope this helps.
Good Luck & Regards,
Merv Weis
_______________________________________________________________________________
___________________________________________________________________
Karen Y. Byrd C511 Richards Bldg.
Systems Manager 3700 Hamilton Wlk.
Univ. of Pa. Philadelphia, PA 19104-6062
School of Medicine Voice: 215/898-6865
Computing and Info. Tech. Fax: 215/573-2277
byrd_at_mscf.med.upenn.edu
karen_at_mail.med.upenn.edu
Received on Wed Jun 24 1998 - 15:45:39 NZST