Dual M.2 SSD's 1% hit rate

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149113
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Dual M.2 SSD's 1% hit rate

Post by 149113 »

I am using the AS6510T with (10) 12TB drives + (2) 480GB M.2 SSD's. The 12TB drives are Ironwolf 7200rpm ST12000VN0008-2PH103 drives. The M.2 are Crucial CT500P2SSD8 and supported hardware per Asustor. The unit is fully maxed out on RAM with 64GB. Attaching screen shots of the config. Why am I getting a 1% hit rate on the SSD drives? The main reason I added these was to increase hit rates but it seems this is not happening at all. What is the fix for this?

I placed a ticket with support a month ago. Not sure the person that replied understood the issue

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AS6404T user
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Re: Dual M.2 SSD's 1% hit rate

Post by AS6404T user »

The hit rate will eventually reach 100% but it takes a couple of days or weeks depending on your usage.
149113
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Joined: Sun Jan 16, 2022 10:05 am

Re: Dual M.2 SSD's 1% hit rate

Post by 149113 »

AS6404T user wrote:The hit rate will eventually reach 100% but it takes a couple of days or weeks depending on your usage.
It's been running for a full year (Oct 2021) and I use it everyday
AS6404T user
Posts: 55
Joined: Fri Nov 08, 2019 11:30 pm

Re: Dual M.2 SSD's 1% hit rate

Post by AS6404T user »

149113 wrote:
AS6404T user wrote:The hit rate will eventually reach 100% but it takes a couple of days or weeks depending on your usage.
It's been running for a full year (Oct 2021) and I use it everyday
Strange. I reset my cache disks a few days ago, and the hit rate is already at 48%. The only difference is that I am using 2 x 450 GB SSD:s in the hard disk bays, not M.2 cards (not available on my model).
149113
Posts: 5
Joined: Sun Jan 16, 2022 10:05 am

Re: Dual M.2 SSD's 1% hit rate

Post by 149113 »

AS6404T user wrote:
149113 wrote:
AS6404T user wrote:The hit rate will eventually reach 100% but it takes a couple of days or weeks depending on your usage.
It's been running for a full year (Oct 2021) and I use it everyday
Strange. I reset my cache disks a few days ago, and the hit rate is already at 48%. The only difference is that I am using 2 x 450 GB SSD:s in the hard disk bays, not M.2 cards (not available on my model).
I've had a ticket in with Asustor for a month and I'll not post the actual replies from the support staff but suffice it to say that it feels like they don't even understand the issue let alone provide next steps. I asked for escalation but the same person keeps responding to the open ticket.
crazynas
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Re: Dual M.2 SSD's 1% hit rate

Post by crazynas »

Cache Hit Rate

SSD cache by default only accelerates random I/O and does not accelerate sequential I/O. The Cache Hit Rate of an SSD cache can be calculated according to the following formula:
Hit Rate of an SSD read-only cache = Accelerated Random Read Counts / Total Random Read Counts * 100%
Hit Rate of an SSD read-write cache = Accelerated Random Read & Write Counts / Total Random Read & Write Counts * 100%
149113
Posts: 5
Joined: Sun Jan 16, 2022 10:05 am

Re: Dual M.2 SSD's 1% hit rate

Post by 149113 »

crazynas wrote:Cache Hit Rate

SSD cache by default only accelerates random I/O and does not accelerate sequential I/O. The Cache Hit Rate of an SSD cache can be calculated according to the following formula:
Hit Rate of an SSD read-only cache = Accelerated Random Read Counts / Total Random Read Counts * 100%
Hit Rate of an SSD read-write cache = Accelerated Random Read & Write Counts / Total Random Read & Write Counts * 100%
OK, so how does that explain a 1% hit rate and others are getting much higher numbers?

Asustor's "solution" was to delete the entire volume and recreate it again and then add the SSD's
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