Re: Feature Request: Support accelerating writes with L2 Storage
Posted: Mon Jun 27, 2016 8:57 am
Have you ever heard of the HP Z Turbo Drive Pro Quad?
There is a similar device from DELL and I believe others will follow soon.
Its a very clever product. Its a base PCIe board that allows to connect 4 M.2 SSDs onto it. It provides necessary cooling and apparently has some RAM with high capacity capacitors as power buffer for save writes. So its a really clever design enhancing SSD exactly where it needs to be.
Best of all: With 4 current M.2 Samsung 950 SSDs 512 GByte you get up to 2 TByte in total with an aggregated write speed around 6 GByte/s and read speed around 9 GByte/s. The already announced successor SSDs from Samsung (which will fit into the HP board too) will allow for 4 TByte in total with write speeds around 9 GByte/s and read speeds around 12 GByte/s. The base board including 2 * 256 GByte Samsung SSDs is around 850 Euros. A 512 GByte SSD is around 300 Euros, so a full 2 TByte drive will cost around 1650 Euro I suspect.
Unfortunately these boards are BIOS locked to HPs zx40 workstation (z840, z640, z440). DELL seems to do the same. But it shows what kind of product we can use/expect soon.
There are also more expensive PCIe SSDs which are not locked to specific machines/mainboards, which get at least somewhere close. As this is around RAM speed of older systems its basically what you are looking for in the long run.
I hope Romex Software is soon implementing the often asked for write caching on L2 and allows also double deffered writes from L1 to L2 to HDD. The latter can be done as I suggested earlier by setting the defer write time from L1 to HDD and L1 to L2 and from L2 to HDD.
Example:
L1->HDD = 1 Day
L1->L2 = 10 seconds
L2->HDD = 1 hour
Your data will be written to L1 RAM cache first, after 10 seconds it will be transferred to L2 SSD cache, where it will stay for 1 hour until it gets written to HDD.
Important:
Even after writing to HDD, the cache is not invalidated/free'ed up - because there is no reason to do this. The cache is read cache at the same time, so subsequent reads of the same data will be pulled from either L1 or L2, and only if the data is no longer there, its going to be pulled from HDD.
There is a similar device from DELL and I believe others will follow soon.
Its a very clever product. Its a base PCIe board that allows to connect 4 M.2 SSDs onto it. It provides necessary cooling and apparently has some RAM with high capacity capacitors as power buffer for save writes. So its a really clever design enhancing SSD exactly where it needs to be.
Best of all: With 4 current M.2 Samsung 950 SSDs 512 GByte you get up to 2 TByte in total with an aggregated write speed around 6 GByte/s and read speed around 9 GByte/s. The already announced successor SSDs from Samsung (which will fit into the HP board too) will allow for 4 TByte in total with write speeds around 9 GByte/s and read speeds around 12 GByte/s. The base board including 2 * 256 GByte Samsung SSDs is around 850 Euros. A 512 GByte SSD is around 300 Euros, so a full 2 TByte drive will cost around 1650 Euro I suspect.
Unfortunately these boards are BIOS locked to HPs zx40 workstation (z840, z640, z440). DELL seems to do the same. But it shows what kind of product we can use/expect soon.
There are also more expensive PCIe SSDs which are not locked to specific machines/mainboards, which get at least somewhere close. As this is around RAM speed of older systems its basically what you are looking for in the long run.
I hope Romex Software is soon implementing the often asked for write caching on L2 and allows also double deffered writes from L1 to L2 to HDD. The latter can be done as I suggested earlier by setting the defer write time from L1 to HDD and L1 to L2 and from L2 to HDD.
Example:
L1->HDD = 1 Day
L1->L2 = 10 seconds
L2->HDD = 1 hour
Your data will be written to L1 RAM cache first, after 10 seconds it will be transferred to L2 SSD cache, where it will stay for 1 hour until it gets written to HDD.
Important:
Even after writing to HDD, the cache is not invalidated/free'ed up - because there is no reason to do this. The cache is read cache at the same time, so subsequent reads of the same data will be pulled from either L1 or L2, and only if the data is no longer there, its going to be pulled from HDD.