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Growing disk groups 7+1 Raid 5 adding 3+1
I have a question about adding to disk groups. If we start out with a disk group of RAID 5 7+1, can you add additional disks into the same disk group using RAID 5 3+1. If so are there any draw backs?
Also when our EMC rep was on site I could have sworn he stated that RAID 5 7+1 meant: 7 disks and one of the 7 used for parity. As I'm looking for my disk groups it looks like there are 8 disks total one being used for parity.
Thank you kindly,
Steven
392
0
Posted June 3rd, 2013 04:00
raid 5 (7+1) means 7 for data and 1 for parity. So you are correct
Fenglin1
6 Operator
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2074 Posts
392
0
Posted June 2nd, 2013 19:00
the disk group in VMAX includes the same type of physical disks ( speed, size) but not includes any raid protection type. I believe you can create symm device whatever raid5 you want in same disk group. the command creating device is like below for you reference.
create dev count=n,
size=n [MB |GB | CYL],
emulation=EmulationType,
config=DeviceConfig,
[, data_member_count=nn]
[, remote_config=DeviceConfig,
remote_data_member_count=nn,
ra_group=n, [remote_mvs_ssid=nnn],
[dynamic_capability=[dyn_rdf | dyn_rdf1_only | dyn_rdf2_only], ]
[, mvs_ssid=nnn]
[, attribute=ckd_meta | savedev | datadev
[in pool PoolName] [member_state=ENABLE | DISABLE], ]
[meta_member_size=n [MB | GB | CYL]]
[meta_config=n [striped | concatenated]]
[, disk_group=nnn| name:DskGrpName,
[remote_disk_group=nnn | name:DskGrpName] ],
[, binding to pool=PoolName
[preallocate size=n [MB |GB | CYL]
[remote_pool=PoolName]]
[, [mapping to dir DirNum:PortNum>
[starting] target = ,
lun=scsi_lun, vbus=fibre_vbus
[starting] base_address ]...]
[[device_attr =
[SCSI3_persist_reserv | ACLX]]...];