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DSM 6.2 through 6.2.4 Flash-Cache (SSD/NVME) worked great.
DSM 7.01 removed only one key feature.
DSM 7.1 now works entirely differently, removing many key features while adding just one feature.
This post encourages discussion on the huge differences in these DSM Flash-Cache features now removed....
Synology DSM 7.0.1 Update-3, worked great with the Synology 10Gb Ethernet and M.2 Adapter Card E10M20-T1, RJ-45; 1 Port SSD/10G Combo-Card on my older DS3617xs.. It *WAS* awesome while it lasted (DSM 7.01 was first to support E10M20-T1 in DS3617sx):
With DSM 7.0.1, Synology's cache system and specifically in my case using this combo-card let you create two separate cache types for use in the same Storage Pool #1: One from SATA-SSD's for Cache #1 to use in Volume #1, and then Second Cache #2 from NVME-SSD's Combo Card Volume #2, for use on *SAME* Storage Pool... BUT NOT anymore!
MAJOR FUNCTIONALITY DELETED DSM 7.1 (using released Update-1), that directly adversely affects Synology's cache strategy and somewhat KILLS my config and this E10M20-T1 combo-card for me, as follows.... :-(
Now, Storage Pool #1 consisting of SATA SSD's and another consisting of the NVMe SSD's this combo-card uses, NOW must use separate PHYSICAL DRIVES to create a MULTIPLE Storage Pool #2 (not just Volume #2). For clarity: NO: You CANNOT just use free space from your existing Storage Pool #1 to use for a Cache Pool #2 to keep using this comb-card. Ouchies.
Also Now, you get an ERROR that Cache Pools cannot contain both SATA-SSD and NVME-SSD. They must be of the same type. This is a HUGE problem for my config, which was fine in 7.0.1 but is now totally broken for my use in 7.1..
NOW: Synology has now posted this info in its official DSM 7.1 "SSD Cache release notes new for 7.1", to try and slow down confused customers like me, asking Synology's Tech Support what is going wrong. It's not wrong: It's a HUGE design change.
Literally, what was working great in DSM 7.0.1 is now IMPOSSIBLE in DSM 7.1 (same storage-pool with multiple volumes cached by different cache types (e.g. SATA/NVME), is NO LONGER SUPPORTED).
Basically, Synology's decision to KILL their best 2 caching features AND this card with these harsh DSM 7.1 limitations being UNABLE to use it for multi-volumes in a *SINGLE* mixed storage pool of SSD and NVME now, is really bad for my uses...
So, now I'm losing the expensive NVMe flash cache for my other volume(s), because I cannot afford to just add PHYSICAL storage bays with expensive EXTRA PHYSICAL HDD's on a whim to accomdite this DSM software change.... This really hurts.
I sure hope Synology puts having MULTIPLE cache pools of a differet type, for a SINGLE storage pool's multiple Volumes, back on their development roadmap ASAP!!
Don't believe me? Here are the links to official Synology articles on this obsecure yet to me very important topic.
DSM 6.2 to 6.2.4 Cache functionality:
Storage Pool:
Create a New Storage Pool | DSM - Synology Knowledge Center
Flash-SSD/NVME Cache:
SSD Cache | DSM - Synology Knowledge Center
Support for Multiple-Volumes SSD caching in same Pool = YES.
Support for caching in-transit files bigger than 1mb (aka Sequential I/O) = YES.
Support for mixing different Cache-Types in same Storage Pool = YES.
Support for Cache Pool of Same-Type to be split-up to Volumes on Same Storage Pool = NO.
DSM 7.0.1 Cache functionality:
Support for caching in-transit files bigger than 1mb (aka Sequential I/O) = NO!
Note: This interim version of DSM had other cache problems they hot-fixed by disabling this key feature, but it's only in various user-forums and not really formally addressed by Synology articles. All other features from DSM 6.2.x are the same.
DSM 7.1 Cache functionality:
Storage Pool:
Create a Storage Pool | DSM - Synology Knowledge Center
Flash-SSD/NVME Cache:
Create an SSD Cache | DSM - Synology Knowledge Center
Support for Multiple-Volumes SSD caching in same Pool = NO!
Support for caching in-transit files bigger than 1mb (aka Sequential I/O) = NO!
Support for mixing different Cache-Types in same Storage Pool = NO!
Support for Cache Pool of Same-Type to be split-up to Volumes on Same Storage Pool = YES.
.....I did not know any of this at the time, and after I followed Synology's recommendation to delete and recreated my flash-caches, now it's too late because Synology prohibits anyone to downgrade DSM in order for me to get these HUGE features back that are now GONE.. :-(
Edit: Clarified DSM 7.0.1 worked almost-the-same but not exactly-same as DSM 6.2.x, as this is quietly undocumented by Synology.
DSM 7.01 removed only one key feature.
DSM 7.1 now works entirely differently, removing many key features while adding just one feature.
This post encourages discussion on the huge differences in these DSM Flash-Cache features now removed....
Synology DSM 7.0.1 Update-3, worked great with the Synology 10Gb Ethernet and M.2 Adapter Card E10M20-T1, RJ-45; 1 Port SSD/10G Combo-Card on my older DS3617xs.. It *WAS* awesome while it lasted (DSM 7.01 was first to support E10M20-T1 in DS3617sx):
With DSM 7.0.1, Synology's cache system and specifically in my case using this combo-card let you create two separate cache types for use in the same Storage Pool #1: One from SATA-SSD's for Cache #1 to use in Volume #1, and then Second Cache #2 from NVME-SSD's Combo Card Volume #2, for use on *SAME* Storage Pool... BUT NOT anymore!
MAJOR FUNCTIONALITY DELETED DSM 7.1 (using released Update-1), that directly adversely affects Synology's cache strategy and somewhat KILLS my config and this E10M20-T1 combo-card for me, as follows.... :-(
Now, Storage Pool #1 consisting of SATA SSD's and another consisting of the NVMe SSD's this combo-card uses, NOW must use separate PHYSICAL DRIVES to create a MULTIPLE Storage Pool #2 (not just Volume #2). For clarity: NO: You CANNOT just use free space from your existing Storage Pool #1 to use for a Cache Pool #2 to keep using this comb-card. Ouchies.
Also Now, you get an ERROR that Cache Pools cannot contain both SATA-SSD and NVME-SSD. They must be of the same type. This is a HUGE problem for my config, which was fine in 7.0.1 but is now totally broken for my use in 7.1..
NOW: Synology has now posted this info in its official DSM 7.1 "SSD Cache release notes new for 7.1", to try and slow down confused customers like me, asking Synology's Tech Support what is going wrong. It's not wrong: It's a HUGE design change.
Literally, what was working great in DSM 7.0.1 is now IMPOSSIBLE in DSM 7.1 (same storage-pool with multiple volumes cached by different cache types (e.g. SATA/NVME), is NO LONGER SUPPORTED).
Basically, Synology's decision to KILL their best 2 caching features AND this card with these harsh DSM 7.1 limitations being UNABLE to use it for multi-volumes in a *SINGLE* mixed storage pool of SSD and NVME now, is really bad for my uses...
So, now I'm losing the expensive NVMe flash cache for my other volume(s), because I cannot afford to just add PHYSICAL storage bays with expensive EXTRA PHYSICAL HDD's on a whim to accomdite this DSM software change.... This really hurts.
I sure hope Synology puts having MULTIPLE cache pools of a differet type, for a SINGLE storage pool's multiple Volumes, back on their development roadmap ASAP!!
Don't believe me? Here are the links to official Synology articles on this obsecure yet to me very important topic.
DSM 6.2 to 6.2.4 Cache functionality:
Storage Pool:
Create a New Storage Pool | DSM - Synology Knowledge Center
Flash-SSD/NVME Cache:
SSD Cache | DSM - Synology Knowledge Center
Support for Multiple-Volumes SSD caching in same Pool = YES.
Support for caching in-transit files bigger than 1mb (aka Sequential I/O) = YES.
Support for mixing different Cache-Types in same Storage Pool = YES.
Support for Cache Pool of Same-Type to be split-up to Volumes on Same Storage Pool = NO.
DSM 7.0.1 Cache functionality:
Support for caching in-transit files bigger than 1mb (aka Sequential I/O) = NO!
Note: This interim version of DSM had other cache problems they hot-fixed by disabling this key feature, but it's only in various user-forums and not really formally addressed by Synology articles. All other features from DSM 6.2.x are the same.
DSM 7.1 Cache functionality:
Storage Pool:
Create a Storage Pool | DSM - Synology Knowledge Center
Flash-SSD/NVME Cache:
Create an SSD Cache | DSM - Synology Knowledge Center
Support for Multiple-Volumes SSD caching in same Pool = NO!
Support for caching in-transit files bigger than 1mb (aka Sequential I/O) = NO!
Support for mixing different Cache-Types in same Storage Pool = NO!
Support for Cache Pool of Same-Type to be split-up to Volumes on Same Storage Pool = YES.
.....I did not know any of this at the time, and after I followed Synology's recommendation to delete and recreated my flash-caches, now it's too late because Synology prohibits anyone to downgrade DSM in order for me to get these HUGE features back that are now GONE.. :-(
Edit: Clarified DSM 7.0.1 worked almost-the-same but not exactly-same as DSM 6.2.x, as this is quietly undocumented by Synology.