Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hello ,
i'm new to drbd and i have done following Setup
( please see attachment )
System-information
2 storage-nodes
---------------
- centos 5.5 x86_64
- vanilla kernel 2.6.33-5 with
scst_exec_req_fifo patch
- drbd 8.3.7 ( kernel )
- infiniband stack ( kernel, no ofed )
- infiniband HCA ( dualport MT26418 )
- cluster setup ( clvmd )
- raidcontroller Adaptec 52445 ( with BBU )
3 VMWARE-HOSTS
--------------
- ESX4 Vsphere
- Vmware MPIO with "fixed-path"
- 4 Pathes for every LUN/vdisk
- vdisks using VMFS3 , no RDMs
DRBD-Setup
----------
- primary/primary Setup
- replication via IPoIB
- Both nodes raidcontroller with BBU
- /dev/sdx ( raid ) as backend
- PV (lvm2) on drbd resource
Replication , split-brain recovery is working fine .
Write speed is about 550 MByte/sec , read speed is
about 900 MByte/sec
(RAID50- 12x SAS , simple sequential test with dd )
Now i'm try to export my LUNs via scst target driver ( ib_srpt )
SCST vdisk are configure with FILEIO and WRITE_TROUGH .
On my Vmware-host i can see the LUNs exported by the two storage-nodes .
On SCST mailinglist i was advised that is it not safe to use
the VMWARE MPIO with round - robin ( VMWARE uses
SPC-2 reserverations ) when running multiple instances of SCST
on different machines .
- using multiple Hosts with one SCST Server is ok
- do not share same LUNs accross different SCST Server
( storage A and storage B can't share their reservation states
for the LUNs )
My Question :
before a write operation of the Vmware-Host is ACK'd
by the SCST/IB Layer (after the data transfer)
the SCST instances dies .
is the data now allready replicated to the other
primary ( and is corruptued because it was not ACK'd)
or will this be handled by the VMFS filesystem ?
When does exactly DRBD flushes to the backend device ?
Has anyone a how-to for a safe intergrating of DRBD and SCST ?
any comments to this setup are welcome !
kind regards
Steve
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