FSYNCS on test server..

[danielparker]

Hi,

I have been testing some HD's & SSD's on my test server (just desktop hardware with a dual 2.7ghz Athlon, 6GB RAM), No Raid Card, just plugged into the motherboards 3GB/s SATA.

SSD (OWC 100GB Mercury Extreme Pro RE) - http://eshop.macsales.com/item/Other World Computing/SSDMXRE100/

Buffered Reads: 225MB/s
Seek: 0.08ms
FSyncs: 2547

WD Velociraptor 300GB

Buffered Reads: 120MB/s
Seek: 5.42ms
FSyncs: 1338

Seagate 500GB 7200RPM ES SATA Drive

Buffered Reads: 72MB/s
Seek: 9.96ms
FSyncs: 1023

My question is: Can I get away without using a Raid card? My current thoughts are to use the SSD as my primary drive, and backup daily to the Velociraptor and not use raid.

I will only have two VM's.. I don't host for anyone else, this is just my data.. One MySQL and the other Apache. Obviously if the SSD fails completely, then I will lose a days data, but as I understand it, SSD's are much more robust that HD's.

Is this a sane idea?
Im after performance.. to do it with raid looks like it will be much more expensive:

All pricing is approximate $U.S
Raid:
Adaptec 5405 $370
Adaptec BBU $120
4 x 15K SAS 146GB Drives $250ea
Total: $1490

Non Raid:
SSD Drive $350
Velociraptor $180
Total: $530

Thoughts?

Daniel

 

[tom]

Finally its up to you do decide. I never put important data on non-raid systems (I learned that all data is important...). and its not just more reliable, its also faster, supports hotplug.

SSD? It looks like there is just not enough statistical data available to see if these disks are more reliable also older filesystems like ext3 are not optimized for SSDs. I am a bit scared when I read about huge internal caches which seems to be unprotected from power failure.

bestprice? I would go for a Adaptec 5405Z (flash protected cache instead of a BBU) with at least two HD of the new series of the WD velociraptor (600GB).

 

[udo]

Hi,
some people has lower values with raid than you reach with the ssd

But some ssd are loosing a lot of performance under continuos read/write-io - so you must test your configuration.
Because the risk of dataloss: of course has a ssd no mechanic, but they can also fail... (no risc no fun)

Udo

 

[zzigge]

Well, the setup on my proxmox hosts is as follows

80gb x25-m ssd as system disk
1-4 1.5tb sata disks with linux software raid

What I did was setting up the system to the ssd, setup the raid with lvm on top, moved the /var/lib/vz slice to the raid. I then created a small (400mb) lv on the ssd and used as external log device for /var/lib/vz.

This gives me around 2400 fsyncs / second when the writecache on the ssd is enabled, around 1000 without.

The advantage of this setup is price, the disadvantage is I can't really ask for help in this forum

ps , yes I know, this way the log data is not redundant, but from what I've read, should the ssd fail, I will still be left with a valid ext3 filesystem, with maybe the last 30 seconds of data lost.

 

[danielparker]

I would go for a Adaptec 5405Z (flash protected cache instead of a BBU) with at least two HD of the new series of the WD velociraptor (600GB).

Today I have purchased the 5405 with BBU.. What would be the better purchase option?

1) 2 x 600GB WD velociraptor Raid 1

or

2) 4 x 300GB WD velociraptor Raid 10

or

3) 2 x 300GB 10K Seagate Savvio SAS Raid 1

or

4) 2 x 146GB 15K Seagate Savvio SAS Raid 1

 

[udo]

Today I have purchased the 5405 with BBU.. What would be the better purchase option?

1) 2 x 600GB WD velociraptor Raid 1

or

2) 4 x 300GB WD velociraptor Raid 10

or

3) 2 x 300GB 10K Seagate Savvio SAS Raid 1

or

4) 2 x 146GB 15K Seagate Savvio SAS Raid 1

Hi,
raid10 speeds up a lot - so i prefer 2 - but SAS-Drives (not all!) are round double as fast in seeking...
Whats about 4*SAS as Raid10?

Udo

 

[danielparker]

Whats about 4*SAS as Raid10?

Basically it is coming down to cost.. I could do 4 x 146GB 10K Seagate Savvio SAS Raid 10

Would this be much better than the 4 x 300GB velociraptor option? Same RPM but half the storage space.

 

[udo]

Basically it is coming down to cost.. I could do 4 x 146GB 10K Seagate Savvio SAS Raid 10

Would this be much better than the 4 x 300GB velociraptor option? Same RPM but half the storage space.

Hi,
i don't know the Seagate Sawio, but i started with an SATA-Raid and 4*WD-Raptor-300 and the next proxmoxserver has an SAS-Raid (Areca1222 - which is also a little bit faster than the SATA-Raid-Controller) with 4 Hitachi-SAS Drives (450GB - HUS154545VLS300).
The different between both configuration are huge.
The pveperf of the SAS-Drives:

pveperf /var/lib/vz
CPU BOGOMIPS:      27291.79
REGEX/SECOND:      1071100
HD SIZE:           543.34 GB (/dev/mapper/pve-data)
BUFFERED READS:    462.00 MB/sec
AVERAGE SEEK TIME: 5.50 ms
FSYNCS/SECOND:     4862.32
DNS EXT:           64.86 ms
DNS INT:           0.58 ms

Udo