Oct 202018
 

On an ESXi host when performing a manual unmap on your storage datastore, you may notice a very large (hidden) file on the datastore root called “.asyncUnmapFile”. This file could be taking up terabytes of space, and you aren’t able to delete this file.

asyncUnmapFile

Typically the asyncUnmapFile is used by the UNMAP feature on ESXi hosts to deal with unmapping and unallocating storage blocks on the SAN. When you run a manual UNMAP, this file should be created and should appear to using “0” (no) space (even if it is). When an UNMAP completes, this file should disappear and be automatically removed by the function. If an UNMAP is interupted, this file will not be deleted, allowing you to restart the process and upon a full successful completion, it should then be deleted.

The Problem

Some time ago, I had an issue when performing a manual UNMAP, where the ESXi host became unresponsive (due to memory issues). The command appeared to be completed, however I believe it caused potential issues or corruption on the iSCSI datastore. In subsequent runs, the UNMAP appeared to be functioning and working, however I didn’t realize that the asyncUnmapFile had grown to around 1.5TB.

This was noticed during a SAN storage audit, where we saw that the virtual pool on the SAN was using up way more storage than it should be on the datastore.

When we identified the file was this large and causing issues, we attempted to perform 2 UNMAPs (different reclaim sizes) to see if it would be automatically cleared afterwards. It had no effect and the file was unchanged.

We also tried to modify the permissions on the file, however when trying to delete it, it would report that the file or folder was not found, or that it does not exist. This was concerning as we were worried about potential datastore corruption.

It was also noticed that in the hostd.log and vmkernel.log we saw some errors where the host believed that the blocks on the datastore had already been freed: “on volume labeled ‘iSCSIDatastore01’ already freed by another host: This may be a non-issue”

The Solution

Unfortunately with all the research we did, we couldn’t find a clear-cut solution. With worries that the datastore may be corrupted, we needed to do something.

A decision was ultimately made to Storage vMotion all the VMs (Virtual Machines) to another datastore on a separate storage pool, delete the now empty LUN, and recreate it from scratch. After this, we used Storage vMotion again to move the VMs back.

Instantly I noticed that the VMs on that datastore were running faster (it’s only been 12 hours, so I’ll be adding an update in a few days to confirm). We no longer have the file on any of our datastores.

If anyone has further insight in to this issue, please leave a comment!

Aug 272018
 

So, what happens in a worst-case scenario where your backup system fails, you don’t have any VM snapshots, and the last thing standing in the way of complete data loss is your SAN storage systems LUN snapshots?

Well, first you fire whoever purchased and implemented the backup system, then secondly you need to start restoring the VM (or VMs) from your SAN LUN snapshots.

While I’ve never had to do this in the past (all the disaster recovery solutions I’ve designed and sold have been tested and function), I’ve always been curious what the process is and would be like. Today I decided to try it out and develop a procedure for restoring a VM from SAN Storage LUN snapshot.

For this test I pretended a VM was corrupt on my VMware vSphere cluster and then restored it to a previous state from a LUN snapshot on my HPe MSA 2040 (identical for the HPe MSA 2050, and MSA 2052) Dual Controller SAN.

To accomplish the restore, we’ll need to create a host mapping on the SAN for the LUN snapshot to a new LUN number available to the hosts. We then need to add and mount the VMFS volume (residing on the snapshot) to the host(s) while assigning it a new signature and then vMotion the VM from the snapshot’s VMFS to original datastore.

 

Important Notes (Read first):

  • When mounting a VMFS volume from a SAN snapshot, you MUST RE-SIGNATURE THE SNAPSHOT VMFS volume. Not doing so can cause problems.
  • The snapshot cannot be mapped as read only, VMFS volumes must be marked as writable in order to be mounted on ESXi hosts.
  • You must follow the proper procedure to gracefully dismount and detach the VMFS volume and storage device before removing the snapshot’s host mapping on the SAN.
  • We use Storage vMotion to perform a high-speed move and recovery of the VM. If you’re not licensed for Storage vMotion, you can use the datastore file browser and copy/move from the snapshot VMFS volume to live production VMFS volume, however this may be slower.
  • During this entire process you do not touch, modify, or change any settings on your existing active production LUNs (or LUN numbers).
  • Restoring a VM from a SAN LUN snapshot will restore a crash consistent copy of the VM. The VM when recovered will believe a system crash occurred and power was lost. This is NOT a graceful application consistent backup and restore.
  • Please read your SAN documentation for the procedure to access SAN snapshots, and create host mappings. With the MSA 2040 I can do this live during production, however your SAN may be different and your hosts may need to be powered off and disconnected while SAN configuration changes are made.
  • Pro tip: You can also power on and initialize the VM from the snapshot before initiating the storage vMotion. This will allow you to get production services back online while you’re moving the VM from the snapshot to production VMFS volumes.
  • I’m not responsible if you damage, corrupt, or cause any damage or issues to your environment if you follow these procedures.

We are assuming that you have already either deleted the damaged VM, or removed it from your inventory and renamed the VMs folder on the live VMFS datastore to change the name (example, renaming the folder from “SRV01” to “SRV01.bad”. If you renamed the damaged VM, make sure you have enough space for the new restored VM as well.

Procedure:

Mount the VMFS volume on the LUN snapshot to the ESXi host(s)
  1. Identify the VM you want to recover, write it down.
  2. Identify the datastore that the VM resides on, write it down.
  3. Identify the SAN and identify the LUN number that the VMFS datastore resides on, write it down.
  4. Identify the LUN Snapshot unique name/id/number and write it down, confirm the timestamp to make sure it will contain a valid recovery point.
  5. Log on to the SAN and create a host mapping to present the snapshot (you recorded above) to the hosts using a new and unused LUN number.
  6. Log on to your ESXi host and navigate to configuration, then storage adapters.
  7. Select the iSCSI initator and click the “Rescan Storage Adapters” button to rescan all iSCSI LUNs.

    VMware ESXi Host Rescan Storage Adapter

    VMware ESXi Host Rescan Storage Adapter

  8. Ensure both check boxes are checked and hit “Ok”, wait for the scan to complete (as shown in the “Recent Tasks” window.

    VMware ESXi Host Rescan Storage Adapter Window for VMFS Volume and Devices

    VMware ESXi Host Rescan Storage Adapter Window for VMFS Volume and Devices

  9. Now navigate to the “Datastores” tab under configuration, and click on the “Create a new Datastore” button as shown below.

    VMware ESXi Host Add Datastore Window

    VMware ESXi Host Add Datastore Window

  10. Continue with “VMFS” selected and select continue.
  11. In the next window, you’ll see your existing datastores, as well as your new datastore (from the snapshot). You can leave the “Datastore name” as is since this value will be ignored. In this window you’re going to select the new VMFS datastore from the snapshot. Make sure you confirm this by looking at the LUN number, as well as the value under “SnapshotVolume”. It is critical that you select the snapshot in this window (it should be the new LUN number you added above).
  12. Select next and continue.
  13. On the next window “Mount Option”, you need to change the radio button to and select “Assign a new signature”. This is critical! This will assign a new signature to differentiate it from your existing real production datastore so that the ESXi hosts don’t confuse it.
  14. Continue with the wizard and complete the mount process. At this point ESXi will resignture the VMFS volume and rename it to “snap-OriginalVolumeNameHere”.
  15. You can now browse the VMFS datastore residing on the LUN snapshot and do anything you’d normally be able to do with a normal datastore.
Copy/Move/vMotion the VM from the snapshot VMFS volume to your production VMFS volume

Note: The next steps are only if you are licensed for storage vMotion. If you aren’t you’ll need to use the copy or move function in the file browsing area to copy or move the VMs to your live production VMFS datastores:

  1. Now we’ll go to the vCenter/ESXi host storage area in the web client, and using the “Files” tab, we’ll browse the snapshots VMFS datastore that we just mounted.
  2. Locate the folder for the VM(s) you want to recover, open the folder, right click on the vmx file for the VM and select “Register VM”. Repeat this for any of the VMs you want to recover from the snapshot. Complete the wizard for each VM you register and add it to a host.
  3. Go back to you “Hosts and VMs” view, you’ll now see the VMs are added.
  4. Select and right click on the VM you want to move from the snapshot datastore to your production live datastore, and select “Migrate”.
  5. In the vMotion migrate wizard, select “Change Storage only”.
  6. Continue to the wizard, and storage vMotion the VM from the snapshot VMFS to your production VMFS volume. Wait for the vMotion to complete.
  7. After the storage vMotion is complete, boot the VM and confirm everything is functioning.
Gracefully unmount, detach, and remove the snapshot VMFS from the ESXi host, and then remove the host mapping from the SAN
  1. On each of your ESXi hosts that have access to the SAN, go to the “Datastores” section under the ESXi hosts configuration, right click on the snapshot VMFS datastore, and select “Unmount”. You’ll need to repeat this on each ESXi host that may have automounted the snapshot’s VMFS volume.
  2. On each of your ESXi hosts that have access to the SAN, go to the “Storage Devices” section under the ESXi hosts configuration and identify (by LUN number) the “disk” that is the snapshot LUN. Select and highlight the snapshot LUN disk, select “All Actions” and select “Detach”. Repeat this on each host.
  3. Double check and confirm that the snapshot VMFS datastore (and disk object) have been unmounted and detached from each ESXi host.
  4. You can now log in to your SAN and remove the host mapping for the snapshot-to-LUN. We will not longer present the snapshot LUN to any of the hosts.
  5. Back to the ESXi hosts, navigate to “Storage Adapters”, select the “iSCSI Initiator Adapter”, and click the “Rescan Storage Adapters”. Repeat this for each ESXi host.

    VMware ESXi Host Rescan Storage Adapter

    VMware ESXi Host Rescan Storage Adapter

  6. You’re done!
Feb 222018
 
HPe MSA 2040 SAN

There’s a new and easier way to find the latest firmware for your HPe MSA SAN!

A new website setup by HPe allows you to find the latest firmware for your HPe MSA 2050/2052, MSA 1050, MSA 2040/2042/1040, and/or MSA P2000 G3. This site will include the last 3 generations of SANs in the MSA product line.

You can find the firmware download site at: https://hpe.com/storage/MSAFirmware

Hewlett Packard Enterprise was also nice enough for provide a brief video on how to navigate and use the page as well. Please see below:

Leave your feedback!

Feb 142017
 

Years ago, HPe released the GL200 firmware for their HPe MSA 2040 SAN that allowed users to provision and use virtual disk groups (and virtual volumes). This firmware came with a whole bunch of features such as Read Cache, performance tiering, thin provisioning of virtual disk group based volumes, and being able to allocate and commission new virtual disk groups as required.

(Please Note: On virtual disk groups, you cannot add a single disk to an already created disk group, you must either create another disk group (best practice to create with the same number of disks, same RAID type, and same disk type), or migrate data, delete and re-create the disk group.)

The biggest thing with virtual storage, was the fact that volumes created on virtual disk groups, could span across multiple disk groups and provide access to different types of data, over different disks that offered different performance capabilities. Essentially, via an automated process internal to the MSA 2040, the SAN would place highly used data (hot data) on faster media such as SSD based disk groups, and place regularly/seldom used data (cold data) on slower types of media such as Enterprise SAS disks, or archival MDL SAS disks.

(Please Note: To use the performance tier either requires the purchase of a performance tiering license, or is bundled if you purchase an HPe MSA 2042 which additionally comes with SSD drives for use with “Read Cache” or “Performance tier.)

 

When the firmware was first released, I had no impulse to try it out since I have 24 x 900GB SAS disks (only one type of storage), and of course everything was running great, so why change it? With that being said, I’ve wanted and planned to one day kill off my linear storage groups, and implement the virtual disk groups. The key reason for me being thin provisioning (the MSA 2040 supports the “DELETE” VAAI function), and virtual based snapshots (in my environment, I require over-commitment of the volume). As a side-note, as of ESXi 6.5, ESXi now regularly unmaps unused blocks when using the VMFS-6 filesystem (if left enabled), which is great for SANs using thin provision that support the “DELETE” VAAI function.

My environment consisted of 2 linear disk groups, 12 disks in RAID5 owned by controller A, and 12 disks in RAID5 owned by controller B (24 disks total). Two weekends ago, I went ahead and migrated all my VMs to the other datastore (on the other volume), deleted the linear disk group, created a virtual disk group, and then migrated all the VMs back, deleted my second linear volume, and created a virtual disk group.

Overall the process was very easy and fast. No downtime is required for this operation if you’re licensed for Storage vMotion in your vSphere environment.

During testing, I’ve noticed absolutely no performance loss using virtual vs linear, except for some functions that utilize the VAAI storage providers which of course run faster on the virtual disk groups since it’s being offloaded to the SAN. This was a major concern for me as block linear based storage is accessed more directly, then virtual disk groups which add an extra level of software involvement between the controllers and disks (block based access vs file based access for the iSCSI targets being provided by the controllers).

Unfortunately since I have no SSDs and no extra room for disks, I won’t be able to try the performance tiering, but I’m looking forward to it in the future.

I highly recommend implementing virtual disk groups on your HPe MSA 2040 SAN!

Feb 082017
 

When running vSphere 6.5 or 6.7 and utilizing a VMFS-6 datastore, we now have access to automatic LUN reclaim (this unmaps unused blocks on your LUN), which automatically unmaps unused storage on your LUNs. This is very handy for thin provisioned storage.

Essentially when you unmap blocks, it “tells” the storage (SAN) that unused (deleted or moved data) blocks aren’t being used anymore and to unmap them (which decreases the allocated size on the storage layer). Your storage LUN must support VAAI and the “Delete” function.

Now taking this a step further, most of you have noticed that storage reclaim in the vSphere client has two settings for priority in the web client; none, or low.

For those of you who feel daring or want to spice life up a bit, you can manually increase the priority through the esxcli command. While I can’t recommend this (obviously VMware chose to hide these options due to performance considerations), you can follow these instructions to change the priority higher.

Manually Configure Storage Reclaim (UNMAP) Priority

To view the current settings:

esxcli storage vmfs reclaim config get --volume-label=DATASTORENAME

To set ESXi reclaim/unmap priority to medium:

esxcli storage vmfs reclaim config set --volume-label=DATASTORENAME --reclaim-priority=medium

To set ESXi reclaim/unmap priority to high:

esxcli storage vmfs reclaim config set --volume-label=DATASTORENAME --reclaim-priority=high

You can confirm these settings took effect by running the first “get” command to view the settings, or view the datastore in the storage section of the vSphere client. While the vSphere client will reflect the higher priority setting, if you change it lower and then want to change it back higher, you’ll need to use the esxcli command to bring it up to a higher priority again.

Happy Virtualizing! Leave a comment!

Feb 072017
 

With vSphere 6.5 came VMFS 6, and with VMFS 6 came the auto unmap feature. This is a great feature, and very handy for those of you using thin provisioning on your datastores hosted on storage that supports VAAI.

I noticed something interesting when running the manual unmap command for the first time. It isn’t well documented, but I thought I’d share for those of you who are doing a manual LUN unmap for the first time. This document will also provide you with the command to perform a manual unmap on a VMFS datastore.

Reason:

Automatic unmap (auto space reclamation) is on, however you want to speed it up or have a large chunk of block’s you want unmapped immediately, and don’t want to wait for the auto feature.

Problem:

I wasn’t noticing any unmaps were occurring automatically and I wanted to free up some space on the SAN, so I decided to run the old command to forcefully run the unmap to free up some space:

esxcli storage vmfs unmap --volume-label=DATASTORENAME --reclaim-unit=200

(The above command runs a manual unmap on a datastore)

After kicking it off, I noticed it wasn’t completing as fast as I thought it should be. I decided to enable SSH on the host and took a look at the /var/log/hostd.log file. To my surprise, it wasn’t stopping at a 200 block reclaim, it just kept cycling running over and over (repeatedly doing 200 blocks):

2017-02-07T14:12:37.365Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:37.978Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:38.585Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:39.191Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:39.808Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:40.426Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:41.050Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:41.659Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:42.275Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-9XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX
2017-02-07T14:12:42.886Z info hostd[XXXXXXXX] [Originator@XXXX sub=Libs opID=esxcli-fb-XXXX user=root] Unmap: Async Unmapped 200 blocks from volume XXXXXXXX-XXXXXXXX-XXXX-XXXXXXXXX

That’s just a small segment of the logs, but essentially it just kept repeating the unmap/reclaim over and over in 200 block segments. I waited hours, tried to issue a “CTRL+C” to stop it, however it kept running.

I left it to run overnight and it did eventually finish while I was sleeping. I’m assuming it attempted to unmap everything it could across the entire datastore. Initially I thought this command would only unmap the specified block size.

When running this command, it will continue to cycle in the block size specified until it goes through the entire LUN. Be aware of this when you’re planning on running the command.

Essentially, I would advise not to manually run the unmap command unless you’re prepared to unmap and reclaim ALL your unused allocated space on your VMFS 6 datastore. In my case I did this because I had 4TB of deleted data that I wanted to unmap immediately, and didn’t want to wait for the automatic unmap.

I thought this may have been occurring because the automatic unmap function was on, so I tried it again after disabling auto unmap. The behavior was the same and it just kept running.

 

If you are tempted to run the unmap function, keep in mind it will continue to scan the entire volume (despite what block count you set). With this being said, if you are firm on running this, choose a larger block count (200 or higher) since smaller blocks will take forever (tested with a block size of 1 and after analyzing the logs and rate of unmaps, it would have taken over 3 months to complete on a 9TB array).

Update May 11th 2018: When running the manual unmap command with smaller “reclaim-unit” values (such as 1), your host may become unresponsive due to a memory overflow. vMotion’s will cease to function, and your ESXi host may need a restart to become fully functional. I’ve experienced this behavior twice. I highly suggest that if you perform this command, you do so while the host is in maintenance mode, and that your restart the host after a successful unmap sweep.

Jul 302016
 

I write today to report of a minor glitch I have identified and confirmed with 2 different HPe MSA 2040 SANs. I’ve identified the issue with multiple firmware versions (even the latest version as of the date of this article being written). The issue stops e-mail notifications from being sent from the MSA 2040 when the SAN is configured with some SMTP relays.

The main concern is that some administrators may configure the notification service believing it is working, when in fact it is not. This could cause problems if the SAN isn’t regularly monitored and if e-mail notifications alone are being used to monitor its health.

 

Configuration:

-MSA 2040 Dual Controller SAN configured with SMTP notifications

-SMTP destination server configured as EXIM mail proxy (in my case a Sophos UTM firewall)

 

Symptoms:

-Test notifications are not received (even though the MSA 2040 confirms OK on transmission)

-Real notifications are not received

-Occasionally if numerous tests are sent in a short period of time (5+ tests within 3 seconds), one of the tests may actually go through.

 

Events and Logs observed:

/var/log/smtp/2016/06/smtp-2016-06-20.log.gz:2016:06:20-20:44:29 SERVERNAME exim-in[16539]: 2016-06-20 20:44:29 SMTP connection from [SAN:CONTROLLER:IP:ADDY]:36977 (TCP/IP connection count = 1)

/var/log/smtp/2016/06/smtp-2016-06-20.log.gz:2016:06:20-20:44:29 SERVERNAME exim-in[18615]: 2016-06-20 20:44:29 SMTP protocol synchronization error (input sent without waiting for greeting): rejected connection from H=[SAN:CONTEROLLER:IP:ADDY]:36977 input=”NOOP\r\n”

 

Resolution:

To resolve this issue, I tried numerous things however the only fix I could come up with, is configuring the SAN to relay SMTP notifications through a Exchange 2013 Server. To do this, you must create a special connector to allow SMTP relaying of anonymous messages (security must be configured on this connector to stop SPAM), and further modify security permissions on that send connector to allow transmission to external e-mail addresses. After doing this, e-mail notifications (and weekly SMTP reports) from the SAN are being received reliably.

 

Additional Notes:

-While in my case the issue was occurring with EXIM on a Sophos UTM firewall, I believe this issue may occur with other E-mail servers or SMTP relay servers.

-Tried configuring numerous exceptions on the SMTP relay with no effect.

-Rejected e-mail messages do not appear in the mail manager, only the SMTP relay log on the Sophos UTM.

-Always test SMTP notifications on a regular basis.

Nov 212015
 
HP MSA2040 Dual Controller SAN with 10Gb DAC SFP+ cables

I’d say 50% of all e-mails/comments I receive from the blog in the last 12 months or so, have been from viewers requesting pictures or proof of the HPe MSA 2040 Dual Controller SAN being connection to servers via 10Gb DAC Cables. This should also apply to the newer generation HPe MSA 2050 Dual Controller SAN.

Decided to finally publicly post the pics! Let me know if you have any questions. In the pictures you’ll see the SAN connected to 2 X HPe Proliant DL360p Gen8 servers via 4 X HPe 10Gb DAC (Direct Attach Cable) Cables.

Connection of SAN from Servers

Connection of SAN from Servers

Connection of DAC Cables from SAN to Servers

Connection of DAC Cables from SAN to Servers

See below for a video with host connectivity:

Jun 072014
 

I’ve had the HPe MSA 2040 setup, configured, and running for about a week now. Thankfully this weekend I had some time to hit some benchmarks. Let’s take a look at the HPe MSA 2040 benchmarks on read, write, and IOPS.

 

First some info on the setup:

-2 X HPe Proliant DL360p Gen8 Servers (2 X 10 Core processors each, 128GB RAM each)

-HPe MSA 2040 Dual Controller – Configured for iSCSI

-HPe MSA 2040 is equipped with 24 X 900GB SAS Dual Port Enterprise Drives

-Each host is directly attached via 2 X 10Gb DAC cables (Each server has 1 DAC cable going to controller A, and Each server has 1 DAC cable going to controller B)

-2 vDisks are configured, each owned by a separate controller

-Disks 1-12 configured as RAID 5 owned by Controller A (512K Chunk Size Set)

-Disks 13-24 configured as RAID 5 owned by Controller B (512K Chunk Size Set)

-While round robin is configured, only one optimized path exists (only one path is being used) for each host to the datastore I tested

-Utilized “VMWare I/O Analyzer” (https://labs.vmware.com/flings/io-analyzer) which uses IOMeter for testing

-Running 2 “VMWare I/O Analyzer” VMs as worker processes. Both workers are testing at the same time, testing the same datastore.

 

Sequential Read Speed:

MSA2040-ReadMax Read: 1480.28MB/sec

 

Sequential Write Speed:

MSA2040-WriteMax Write: 1313.38MB/sec

 

See below for IOPS (Max Throughput) testing:

Please note: The MaxIOPS and MaxWriteIOPS workloads were used. These workloads don’t have any randomness, so I’m assuming the cache module answered all the I/O requests, however I could be wrong. Tests were run for 120 seconds. What this means is that this is more of a test of what the controller is capable of handling itself over a single 10Gb link from the controller to the host.

 

IOPS Read Testing:

MSA2040-MaxIOPSMax Read IOPS: 70679.91IOPS

 

IOPS Write Testing:

MSA2040-WriteOPSMax Write IOPS: 29452.35IOPS

 

PLEASE NOTE:

-These benchmarks were done by 2 seperate worker processes (1 running on each ESXi host) accessing the same datastore.

-I was running a VMWare vDP replication in the background (My bad, I know…).

-Sum is combined throughput of both hosts, Average is per host throughput.

 

Conclusion:

Holy crap this is fast! I’m betting the speed limit I’m hitting is the 10Gb interface. I need to get some more paths setup to the SAN!

Cheers

 

Jun 072014
 

While doing some semi-related research on the internet, I’ve come across numerous how-to and informational articles explaining how to configure iSCSI MPIO, and advising readers to incorrectly use iSCSI port binding. I felt the need to whip up a post to explain why and when you should use iSCSI port Binding on VMware vSphere.

This post applies to all versions of VMware vSphere, including 5, 5.5, 6, 6.5, and 6.7.

What does iSCSI port binding do

iSCSI port binding binds an iSCSI initiator interface on a ESXi host to a vmknic and configures accordingly to allow multipathing in a situation where both vmknics are residing in the same subnet. In normal circumstances without port binding, if you have multiple vmkernels on the same subnet, the ESXi host would simply choose one and not use both for transmission of packets, traffic, and data. iSCSI port binding forces the iSCSI initiator to use that adapter for both transmission and receiving of iSCSI packets.

In most simple SAN environments, there are two different types of setups/configurations.

  1. Multiple Subnet – Numerous paths to a storage device on a SAN, each path residing on separate subnets. These paths are isolated from each other and usually involve multiple switches.
  2. Single Subnet – Numerous paths to a storage device on a SAN, each path is on the same subnet. These paths usually go through 1-2 switches, with all interfaces on the SAN and the hosts residing on the same subnet.

A lot of you I.T. professionals know the the issues that occur when you have a host that is multi-homed, and you know that in normal typical scenarios with Windows and Linux, that if you have multiple adapters residing on the same subnet, you’ll have issues with broadcasts, and in most cases you have absolutely no control over what communications are initiated over what NIC due to the way the routing table is handled. In most cases all outbound connections will be initiated through the first NIC installed in the system, or whichever one is inside of the primary route in the routing table.

When to use iSCSI port binding

This is where iSCSI Port Binding comes in to play. If you have an ESXi host that has vmks sitting on the same subnet, you can bind the iSCSI initiators to the physical NICs. This allows multiple iSCSI connections on multiple NICs residing on the same subnet.

So the general rule of thumb is:

  • One subnet, iSCSI port binding is the way to go!
  • Two or more subnets, DON’T USE ISCSI PORT BINDING! It’s just not needed since all vmknics are residing on different subnets.

Additional Information

Here’s two links to VMWare documentation explaining this in more detail:

http://kb.vmware.com/kb/2010877
http://kb.vmware.com/kb/2038869