VMWare 6.7 A Blast From The Past

Or A Blast To Their Market?

I’ve used VMWare on and off over the years but mainly during the pre-opensource days before the days of Virtualbox, KVM, Xen, OpenVZ etc…  and have dabbled and helped maintain some VMWare clusters over the years.

Anyone familiar with VMWare or who Google’s it will see lots of dire warnings about upgrading to the next version since the upgrades often break existing servers.  This is mainly not because of the Linux Kernel but VMWare seems to have a policy of blacklisting and hardcoding what network adapters, ILOs and CPUs are supported in each release.

Indeed the majority of blogs you will find deal exclusively with warnings of what is not supported and how to get around various restrictions.

But 6.7 seems like a marked departure from the standard.  It has dropped support for the majority of CPUs previously supported even up to 6.5.

I’ve also found it be fairly buggy especially getting vSphere working nicely on 6.7 ESXi hosts.

So this brings me to the next point, VMWare has literally shrank their market share but making it so their existing customers or a lot of people who may have used VMWare literally cannot use it (at least not with the latest 6.7 version).  Since there is not a lot of hardware that supports 6.7 the logical solution for many, even existing users is to simply migrate their VMWare VMs to something opensource based on KVM whether that would be Proxmox, oVirt, OpenStack etc…

Now, I do understand VMWare wants to prevent their marketshare and they’ve likely worked out agreements with hardware manufacturers on what gets obsoleted since a lot of large corporate customers will simply just buy brand new hardware that is supported.

But to me it’s just not a green solution when the same “obsolete” hardware is more than capable of supporting large scale computing infrastructure for a long time to come.  Computing power is so affordable and up there today the problem for hardware manufacturers is that so many organizations even with old hardware don’t need to upgrade (of course save for VMWare mandatory hardware obsoletion).

Aside from all of this VMWare is a fairly good system but I feel it is starting to quickly become attractive after reviewing a lot of community feedback and talking to colleagues in the industry.  There’s a huge push to migrate to KVM based virtualization and I feel the latest VMWare 6.7 will hasten this move.

RAID in 2018

Still Not Quite Obsolete

I’ve talked to a lot of professionals in the IT industry and some surprisingly don’t even know what RAID is!  Others think it is unnecessary, while some think RAID is a replacement for backups still (something admins and hardware techs have been harping about for decades now).  First, I’ll give a quick introduction into what RAID is, what it isn’t and its applications in the real world.

RAID stands for Redundant Array of Independent Disks.  I think the term is a little bit unnecessary in todays’ world but let’s break it down.

First of all we are talking about an array of connected, separate hard disk drives.  These could be 2.5″, 3.5″, SAS, SATA or SSD as far as our implementation and OS they are all essentially the same to the computer that they are connected to.

There are 5 levels or versions of RAID as follows:

  1. RAID 0 AKA striping (two drives required).  This takes two identical hard drives and combines their performance and capacities to make what appears to be a single drive.  Performance with 0 is excellent but the disadvantage is that a failure of any single disk will result in dataloss and the array going offline.  There is no recovery except for backups.   I never recommend RAID 0.
  2. RAID 1 AKA mirroring (two drives required).  It is called mirroring because both drives contain an identical copy of the data. Performance is enhanced on reads because data can be read twice as fast but simultaneously reading from the 2 separate hard drives at once.  There is a performance penalty in terms of writing since the data must be written to both drives at once (however this is usually not an issue for most servers since the majority are read intensive on average).
  3. RAID 5 (3 + drives required).  RAID 5 has in the distant past been one of the most common RAIDs as it provides enhanced performance and some redundancy but it is very prone to faults, failures and slow rebuild times.  It uses a parity drive that is essentially spread between the others but this parity often results in performance degradation unless a hardware RAID card is used.    It can withstand a single drive failure but NOT 2 drives.  Performance of reads is good but the parity calculations slow down performance.
  4. RAID 6 (4+ drives required).  Similar to RAID 6 but two drives are used for parity so it could survive 2 drives failing and is more fault tolerant.  It takes even longer to rebuild on RAID 6 than RAID 5. Performance of reads is good but the parity calculations slow down performance.
  5. RAID 10 AKA 1+0 (requires 4 or more drives).  It is a combination of the sum of two RAID 1 arrays, striped together as a RAID 0.  It delivers excellent performance and is fault tolerant (a drive of each RAID 1 could die without any ill effect aside from some performance reduction).  Rebuild times are similar to RAID 1 and are much faster than RAID 5 or 6.

Rather than over complicating this issue I will try to give a practical take in 2018 of what RAID means.  Some have said RAID is obsolete but usually they are referring to the nearly impossible resync or rebuild times on large multi-terabyte RAID 5/6 arrays.  I would agree there as I’ve never liked RAID 5 or 6 and whether you like it or not it is very impractical to use.

So what is the best way to go?

RAID 1 If you only have 2 drives then I think RAID 1 is an excellent trade off.  It is quick and easy to resync/rebuild, a single drive can die and you will still not have any data loss, yet when both are active you have a performance boost in

RAID 10 If you have 4 drives you gain extra performance in a RAID 10 configuration with fault tolerance that a single drive on each RAID 1 could die without dataloss.

The main disadvantage is that with RAID 1 and RAID 10 you are essentially losing 50% of your storage space but since storage/drives are relatively cheap I think it’s been a worthy tradeoff.

There are some people who spout that “drives are more reliable today” and “you don’t need RAID anymore” but I hardly find this true.  I’d actually argue that SSD drives may be more unreliable or unpredictable than mechanical hard drives.  One thing we can all agree on is that the most likely component to fail in a server is a hard disk and that’s not likely to change any time soon as much as we like to believe flash based storage is more reliable.  I’d also ask anyone who thinks running on a single drive (even with backups) that isn’t the performance benefit and redundancy worth running RAID?  I’m sure most datacenter techs and server admins would agree that it is much better to hotswap/replace a disk than it is to deal with downtime and restoring from backups right?

Now for the warnings.  RAID “protection” is NOT a replacement for backups even if nothing ever dies.  The reason for this is to understand the misleading term of RAID “protection” that some in the industry use.  It is true in sense that you are protected from dataloss if a single drive fails (or possibly 2 in some RAID levels).  However this doesn’t take into account natural disasters, theft, accidental or willful deletion or destruction of data.

I’d say as it stands in 2018 and beyond that everyone should be using at least RAID1 or RAID10 if possible in nearly every use case.  There are a few possible exceptions to this rule but they are rare and even then you should aim for as much redundancy as possible.

In conclusion, if you can use RAID 1, preferably RAID 10. If you can’t use RAID, learn and use it anyway.

Cheers!
A.Yasir