Questions[emc](server)

I routinely cannot unload the Qlogic fibre module qla2xxx under CentOS 5 or 6. These machines are running StorNext cvfs, EMC powerpath and hostagent. Nothing else should ever be touching the fibre. All three of these processes have been stopped before trying to remove the module. The interesting thing of the output below is the lsmod: qla2xxx is being used by 45 things but none are listed. There are no "fibre-ish" processes visible (that I can tell) after running sudo ps ax. I have not tried a "force (-f)" removal Force removal (-f) does not help the situation.

# service cvfs status
Active SNFS mountpoints:
Error: fsmpm not running!

# service PowerPath stop
Stopping PowerPath: PowerPath is not running done

# service hostagent status
hostagent is stopped

# modprobe -v -r qla2xxx
FATAL: Module qla2xxx is in use.

# rmmod -v qla2xxx
ERROR: Module qla2xxx is in use

# lsmod | grep qla
qla2xxx               366555  45 
scsi_transport_fc      52241  1 qla2xxx

# modprobe --show-depends qla2xxx
insmod /lib/modules/2.6.32-220.7.1.el6.x86_64/kernel/drivers/scsi/scsi_tgt.ko 
insmod /lib/modules/2.6.32-220.7.1.el6.x86_64/kernel/drivers/scsi/scsi_transport_fc.ko 
insmod /lib/modules/2.6.32-220.7.1.el6.x86_64/kernel/drivers/scsi/qla2xxx/qla2xxx.ko ql2xfailover=0

# modprobe -r -v scsi_transport_fc
FATAL: Module scsi_transport_fc is in use.

# modprobe --show-depends scsi_transport_fc
insmod /lib/modules/2.6.32-220.7.1.el6.x86_64/kernel/drivers/scsi/scsi_tgt.ko 
insmod /lib/modules/2.6.32-220.7.1.el6.x86_64/kernel/drivers/scsi/scsi_transport_fc.ko

# lsmod | grep scsi_
scsi_transport_fc      52241  1 qla2xxx
scsi_tgt               12173  1 scsi_transport_f

# modprobe -r -v scsi_tgt
FATAL: Module scsi_tgt is in use.

# modprobe --show-depends scsi_tgt
insmod /lib/modules/2.6.32-220.7.1.el6.x86_64/kernel/drivers/scsi/scsi_tgt.ko 

Update: There is a kernel thread persisting for each HBA on the host, which should be killed when I attempt to remove the module.

# ps ax | grep qla
  551 ?        S<     0:00 [qla2xxx_0_dpc]
  557 ?        S<     0:00 [qla2xxx_1_dpc]
  563 ?        S<     0:00 [qla2xxx_2_dpc]
  569 ?        S<     0:00 [qla2xxx_3_dpc]

I am in the process of setting up our vSphere 5 environment. With previous version of vSphere I have used the native pathing with VMware but I now want to investigate Powerpath/VE since it now works for v5. Has anyone swapped over to using Powerpath on your hosts and if so have you seen any performance hits/increases?

I just added a few LUN's to our new EMC VNX, and the LUN ID's are not consistent..

Screenshot from EMC Unisphere

Screenshot from VMWare vSphere

If you study the two screenshots carefully, you'll notice that the Unique ID is identical, yet the LUN ID's differ. I'm a bit at a halt here, and I'm not sure if I should call EMC and blame them, or start searching the net for potential vSphere bugs..

We have a new VNX5300 waiting to get configured, and I need to plan out the network infrastructure before the EMC tech arrives. It has 4x1gbit iSCSI per SP (8 ports in total), and I'd like to get the most out of the performance until we jump over to 10gig iSCSI.

From what I can read from the docs - the recommendation is to use only two ports per SP, with 1 active and 1 passive. Why is this? It seems kind of pointless to have quad-port i/o-modules and then recommend to not use more than two of them?

Also - I'm a bit unsure about the zoning. The best practices guide state that you should separate each port on each SP from each other on different logical networks. Does this mean that I have to create 4 logical networks to be able to use all 8 ports?

It also gives the following example:

Does this mean that A0 and B0 should sit on the same physical switch aswell? Won't this make all traffic go on one switch (if both A1 and B1 are passive)?

Edit: Another brainpuzzle

I don't get it - each host (as in server) should not have more iSCSI bandwidth available than the storage processor. What on earth does this matter? If serverA have 1gbit and serverB have 100mbit, then the resulting bandwith between them is 100mbit. How can this result in some kind of oversubscription?

Edit4: Wait, what. Active and passive ports? The VNX runs in a ALUA configuration with asymmetrical active/active.. there shouldn't be any passive ports, only preferred ones..

I have a Sun M4000 connected to an EMC CX4-120 array with a write-heavy database. Writes peak at around 1200 IO/s and 12MB/s.

According to EMC, I am saturating the write cache on the EMC array.

I think the simplest solution is to move the redo logs to a DRAM based SSD. This will reduce the load on the EMC array by half and apps won't be seeing log buffer waits. Yes, the DBWR may become a bottleneck, but the apps won't be waiting for it (like they do on redo commits!)

I currently cycle through about 4 4GB redo logs, so even 20GB or so of SSD would make a big difference. Since this is short-term storage and is constantly being overwritten, Flash based SSDs probably aren't a great idea.

The M4000 doesn't have any extra drive lots, so a PCI-E card would be perfect, I could go external or move boot volumes to the EMC and free up the local drives.

Sun sells a Flash Accelerator F20 PCIe card, but that seems to be a cache for some SATA disks, not a DRAM SSD solution. Details are sketchy, it doesn't list the M4000 as supported, and I'm tired of fighting Sun's phone tree looking for human help. :(

Do others agree that a DRAM SSD is the way to go? Any hardware recommendations?

UPDATE In addition to the info in a comment below, I tried various settings for "commit_write" and it didn't make a difference.