Backups + HP SmartCache (like CacheCade)

[matt_778]

I have a small single host VMware setup I am designing and will be going with a single ESXi HP Host with DAS.

I am thinking of procuring a couple of HP SSDs and enabling Read/Write Caching on the Smartarray card (HP SmartCache http://www8.hp.com/us/en/products/serve ... id=5364342)

Backups with be Network Mode via a seperate Physical Backup host with replications during the day (to a 2nd ESXi host with DAS)

Do I have to be careful about flushing the SSD cache prior to backups? Is there anything to be mindful of?

Cheers

[PTide]

Hi,

Backups with be Network Mode via a seperate Physical Backup host with replications during the day (to a 2nd ESXi host with DAS)

What kind of NIC is installed on the HP host? Also what's going to be used as a target for backups?

Do I have to be careful about flushing the SSD cache prior to backups? Is there anything to be mindful of?

Since SSD cache stores the data that is accessed most frequently, I suspect that most part of the data that has been written to cache might be useful during backup session however that's just an assumption and should be tested in a lab. Also if not the source will be a bottleneck during backup session then SSD cache won't be helpful for backup performance at all.

Thank you.

[matt_778]

Hi,

The backup host will be teamed via 2 x 1Gb - but the point of the SSD is not to speed up backups, the cache resides inside the ESXi host with the aim to improve performance during day to day VM operations.
I am more wanting to know if Veeam will capture valid backups, considering that potentially some data could be in the write cache and not actually layed down onto the disks?

[PTide]

I am more wanting to know if Veeam will capture valid backups, considering that potentially some data could be in the write cache and not actually layed down onto the disks?

That could be dangerous if you used volatile memory without BBU and chose write-back caching policy - in this case you could lose cached data if the powerloss occurred and no flush took place. Regarding the absence of data on the primary sotrage (HDD) - HP SmartCache is a controller based solution thus it manages data integrity on a hardware level, providing a transparent access to .vmdk data so I don't expect any problems with backups.

[Gostev]

Well, not necessarily... for example, I know that PernixData accelerator users have to trigger certain command with a pre-job script to dump all caches to disk, otherwise backup will be corrupted. So, I would definitely consult with the vendor on this, if I were you.

[tsightler]

PernixData is somewhat unique because it's host based read/write caching of any storage backend. Because the backend storage is unaware of this caching, any I/O that goes directly to the storage, bypassing the host, for example data read via Direct SAN or hotadd on a different host, can potentially be inconsistent.

CacheCade/SmartCache technologies are performed by the storage controller, not at the host level. It's basically just a RAID controller that uses SSD for the read read/write cache instead of battery backed NVRAM in a hybrid storage style configuration. Nothing special really and very common these days.

[matt_778]

Posted here - no hits yet
http://community.hpe.com/t5/ProLiant-Se ... -p/6856355