SSD caching on Synology and Qnap – will it improve performance?

SSD caching on Synology and Qnap – will it improve performance?

Any advice on SSD caching? I’ve got 2 M.2 Sata SSDs installed in raid 0 (2 * 512GB Samsung 850 Evo) in my QM2 expansion card with 10GBE networking and I’m not getting the performance boost to commonly accessed files that i was expecting. I can see that data is being cached but not sure how to measure performance increase. I was also transferring files to my samsung 960 evo m.2 NVME SSD so there shouldn’t be a bottleneck there. I’m maxing out at around 350MB/s which was the same with the SSDs installed.

The objective of enabling SSD cache is to increase the performance of random access to a small portion of data that is frequently accessed in the storage space. For example, both large sequential read or write operations (e.g., HD video streaming) and entirely random data reading patterns lack re-reading patterns, and thus will not benefit significantly from SSD caching. For general applications, it is recommended to enable the Skip sequential I/O option, so that sequential I/O can still pass through to the drives of the storage space.

https://www.synology.com/en-uk/knowledgebase/DSM/help/DSM/StorageManager/genericssdcache

SSD Cache

SSD cache can improve the performance of random access by storing frequently accessed data on the SSD cache. SSD cache can be mounted on a volume or iSCSI LUN (Block-Level). There are two types of SSD cache:

  • Read-only cache can consist of 1 to 12 SSDs which can be mounted respectively in a basic or RAID 0 configuration to improve the random read performance of the storage space on which it is mounted.

    Note:SSD read-only cache stores copies of data from the volume; thus, no data loss will occur even if the read-only cache has crashed.

  • Read-write cache can be mounted in a RAID 1 / RAID 5 / RAID 6 configuration, depending on the number of SSDs (up to 12 SSDs), to improve the random read and write performance of the storage space on which it is mounted.

Both types of SSD cache implement an LRU (Least Recently Used) algorithm to swap the data in the cache.

 

 

SSD– A Solid State Drive is a data storage device using integrated circuit assemblies as
memory to store data persistently. This enables a much faster transfer speed than
HDD.

HIT Rate– How often a searched-for item is actually found in the cache. The greater the number of
requests that can be served from the cache, the faster the overall system performance
becomes.

IOPS– Input / Output Operations Per Second, is a common performance measurement
used to benchmark computer storage devices.

 

SSD cache technology
QNAP solid-state drive (SSD) cache technology is based on disk I/O reading caches.
When the applications of the Turbo NAS access the hard drive(s), the data will be stored in
the SSD. When the same data are accessed by the applications again, they will be read
from the SSD cache instead of the hard drive(s). The commonly accessed data are stored
in the SSD cache. The hard drive(s) will only be accessed when the data could not be
found from the SSD.

Applications and benefits
 Database: MySQL, MS SQL Server, etc.
 Virtual machine: VMware, Hyper-V, XenServer, etc

http://files.qnap.com/news/pressresource/product/SSDcache-whitepaper_en.pdf

 

 

Uncompromising performance for demanding applications

The SSD cache feature on QNAP NAS accelerates IOPS performance by up to 10 times and reduces latency by 3 times for storage volumes. It is perfect for IOPS-demanding applications including databases and virtualization to significantly improve overall workflow.

SSD cache volume varies with the size of RAM
Cache capacity RAM requirement
512GB ≧ 1GB
1TB ≧ 4GB
2TB ≧ 8GB
4TB ≧ 16GB

 

 

 

 

https://www.qnap.com/solution/ssd-cache/en/

 

SSD cache compatible NAS models

NAS Models SSD Cache Slot Supported SSD Cache Slot Number Remark
TDS-16489U All All
TES-x85U All All The rear SSD slots only support 2.5-inch SATA 6Gb/s drives
TVS-ECx80U-SAS All All This series also has 2 mSATA slots for caching.
TVS-ECx80U-SAS R2 All All This series also has 2 mSATA slots for caching.
TS/TVS-x79U-SAS All All
SS-x79U-SAS All All
TS-ECx80U Disk 1, 2, 3, 4 4 This series also has 2 mSATA slots for caching.
TS-ECx80U R2 Disk 1, 2, 3, 4 4 This series also has 2 mSATA slots for caching.
TS-ECx80 Pro Disk 5, 6, 7, 8 4 This series also has 2 mSATA slots for caching.
TVS-ECx80 Disk 5, 6, 7, 8 4 This series also has 2 mSATA slots for caching.
TS/TVS-x79U Disk 3, 4 2
TS/TVS-x79 Pro Disk 7, 8 2
TVS-882ST2, TVS-882ST3, TVS-882S All All
TVS-x82T TVS-682T/882T: SSD slot 1, 2
TVS-1282T: SSD slot 1, 2, 3, 4
TVS-682T/882T: 2
TVS-1282T: 4
This series also has 2 M.2 SATA III slots for caching.
TVS-x82 TVS-682/882: SSD slot 1, 2
TVS-1282: SSD slot 1, 2, 3, 4
TVS-682/882: 2
TVS-1282: 4
This series also has 2 M.2 SATA III slots for caching.
TS-x73U All All The built-in M.2 SSD slots are recommended for caching.
TVS-x73 All All This series also has 2 M.2 SATA III slots for caching.
TVS-x71 Disk 1, 2, 3, 4 4
TVS-x71U Disk 1, 2, 3, 4 4 This series also has 2 mSATA slots for caching.
TS-x70U Disk 3, 4 2
TS-x70 Last two trays 2
TS-x70 Pro Last two trays 2
TS-1635 Disk 1, 2, 3, 4 4
TS-x63U All All
TVS-x63 All All Disk slots 1 & 2 are recommended for caching.
TS-563 All All Disk slots 1 & 2 are recommended for caching.
TS-x51 All All
TS-453U All All
TS-453U-RP All All
TS-451U All All
TS-853U Disk 5, 6, 7, 8 4
TS-853U-RP Disk 5, 6, 7, 8 4
TS-1253U Disk 9, 10, 11, 12 4
TS-1253U-RP Disk 9, 10, 11, 12 4
TS-x53B All All The last two disk slots are recommended for caching.
TS-x53A All All Disk slots 3 and above are recommended for caching.
TS-x53 Pro All All
TS-x53S Pro All All
TS-531P All All Disk slots 1-4 are recommended for caching.
TS-x31+ All All
TS-x31X All All
TS-x31XU All All
TS-453mini Disk 1, 2 2
TS-453Bmini All All Disk slots 3 & 4 are recommended for caching.

Synology NAS list with M.2 SSD option:

IBSY-918P Synology

Synology DiskStation NAS DS918+ 4-Bay (4GB RAM)

IBSY-FS1018 Synology

Synology FlashStation NAS FS1018 12-Bay 2.5″, 4x 1GbE, PCIe

IBSY-1817P Synology

Synology DiskStation NAS DS1817+ (2GB) 8-Bay, 4x 1GbE, PCIe

IBSY-1517P Synology

Synology DiskStation NAS DS1517+ (2GB) 5-Bay, 4x 1GbE, PCIe

IBSY-3018 Synology

Synology DiskStation NAS DS3018xs 6-Bay, 4x 1GbE, PCIe

IBSY-1517P8 Synology

Synology DiskStation NAS DS1517+ (8GB) 5-Bay, 4x 1GbE, PCIe

IBSY-1817P8 Synology

Synology DiskStation NAS DS1817+ (8GB) 8-Bay, 4x 1GbE, PCIe

IBSY-918P8 Synology

Synology DiskStation NAS DS918+ (8GB) 4-Bay (8GB Synology RAM)

 

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