2. FAST Cache should always be highly utilized, especially when you only have a relatively small size of 2 disks. Generally, I find the best metrics are the hit ratios, which you can measure through analyzer, M & R or even Unisphere Central.
3. In a 2 disk RAID 1, 1 drive failure degrades the Cache and it then serves reads only until it's fixed.
4. Correct, but you should have a spare, so the impact would then be minimal.
5. The FAST Cache drives are SLC so endurance is well rated. The MTBF stats are broad stats only, failures of components can just happen at anytime. Although, I have found the drives used to be very reliable.
6. FAST Cache is non-volatile so no flush/destage process is required.
brettesinclair
2 Intern
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715 Posts
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July 22nd, 2015 04:00
1. FAST Cache is R/W and mirrored in RAID 1.
2. FAST Cache should always be highly utilized, especially when you only have a relatively small size of 2 disks. Generally, I find the best metrics are the hit ratios, which you can measure through analyzer, M & R or even Unisphere Central.
3. In a 2 disk RAID 1, 1 drive failure degrades the Cache and it then serves reads only until it's fixed.
4. Correct, but you should have a spare, so the impact would then be minimal.
5. The FAST Cache drives are SLC so endurance is well rated. The MTBF stats are broad stats only, failures of components can just happen at anytime. Although, I have found the drives used to be very reliable.
6. FAST Cache is non-volatile so no flush/destage process is required.
DukeR1337
2 Intern
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208 Posts
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July 22nd, 2015 05:00
Thank you. Is the hotspare still required in Gen2 it is not that clear in the white papers.
brettesinclair
2 Intern
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715 Posts
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July 22nd, 2015 05:00
You don't have to use spares, but IMO they should always be used.
DukeR1337
2 Intern
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208 Posts
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July 22nd, 2015 06:00
Ok so we dont have to use spare in gen1 and gen2 but it is always recommended. It was a little bit unclear in the white papers.
Thank you