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51 Posts
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1718
create meta: best practice.
Hello,
i want to create one meta with 2 members:
what is the best practice:
1/: indicate to symmetrix what dev member it must take for create the meta
form meta from dev XXXX config=striped,
stripe_size=2 cyl;
add dev YYYY to meta XXXX;
or let the symmetrix take one device member free:
form meta from dev XXXX config=striped,
stripe_size=2 cyl, count=2;
thanks
Quincy561
1.3K Posts
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December 23rd, 2011 06:00
Contiguous devices does not guarantee that the meta will not share spindles. If the meta has enough members and there are not many drives, you could get sharing anyway.
Thick metas should not share the same drives if at all possible.
RobertDudley
448 Posts
0
December 19th, 2011 07:00
A lot of people like the meta volumes they create to be contiguous symmetrix devices, one way to ensure that is to create then add them in contiguous order. If you don't care about contiguous you can let the symmetrix choose the next meta member.
Non-contiguous meta volumes used to play havoc with certain functions; that really isn't a concern any longer. I still prefer to create contiguous meta volumes though.
jvtv
42 Posts
1
December 23rd, 2011 02:00
If you identify the devices that you want to add to the meta device you can assure that they are devs that don't share physical spindles, which improves performance. Contiguous devices on the DMX (if the bin file is done as specified by EMC) guarantees that there's no spindle sharing so it's better if you create your meta with this considerations.
elearning
51 Posts
0
December 23rd, 2011 06:00
thanks a lot all
dynamox
2 Intern
2 Intern
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20.4K Posts
1
December 23rd, 2011 06:00
Spindle is oftet referred to physical drive.
elearning
51 Posts
0
December 23rd, 2011 06:00
what about spindle sharing ? on many physical drives?
does that mean, you can decide in bin.file if the system takes spindle on the same physical drive or not ?
sasi_symmetrix
5 Posts
0
March 25th, 2012 02:00
what is the difference, if we let the symmetrix automatically choose the meta member rather than manually specifying meta members in command file. Are contiguous devices more advantageous in meta volume? Does symmetrix choose contiguous devices in case of automatic selection? pls clarify me quincy.
Thanks in advance.
Quincy561
1.3K Posts
1
March 25th, 2012 03:00
For thick volumes, the main thing you want to avoid is meta members sharing the same physical disk as stated before.
With RAID5 7+1, if you had 80 active disks in the box (not counting spares), you could make a 10 member meta without sharing disks. Any additional members and they would have to be at least one member sharing the disk.
Generally consecutive volumes don't share spindles, but it is worth checking, as it depends on what volume number you start with.
I think most of the configuration scripts will block or warn against spindle sharing unless you specify the volumes to use.