System setup and noted issues
Synology Disk Station DS508 performance
We used Iometer version 2006.07.27 over SMB shares. We equipped the DS508 with five 500GiB Seagate ST3500320AS drives, although, due to an oversight, we didn't remove the jumpers to set the drives to operate at 3Gbps, running at SATA1 speeds of 1.5Gbps.
The DS508's performance is tested in three states - a five-disk RAID5 array, a degraded array when one of the hard disks (disk two) is pulled from the system, and during the rebuild process after a disk is reinserted.
Setup
The host machine for Iometer is as follows:
| Component | Details |
|---|---|
| CPU | Intel Core 2 Extreme QX9770 (3.2GHz, 1,600MHz FSB) |
| Motherboard | eVGA 132 CK-NF79 (NVIDIA nForce 790i Ultra SLI chipset) - nforce 15.17 |
| Memory | 2GiB (2x 1GiB) Corsair 1,066MHz DDR3 (CM3X-1024-1066C7) |
| Disks | Seagate 160GB SATAII (ST3160812AS) |
| Graphics | Sapphire Radeon HD3450 512MiB - CATALYST 8.6 |
| Network | NVIDIA network controller, 1Gbps, 9000byte frames |
| OS | Microsoft Windows XP SP3 |
Below is our Iometer test regime:
| Option/test | Configuration |
|---|---|
| Outstanding I/Os | 10 |
| Individual test run time | 30 seconds |
| Test file | 1GB |
| Sequential read test access spec | 64K transfers 100% sequential 100% read |
| Sequential write test access spec | 64K transfers 100% sequential 100% write |
| Random read and write access spec | 64KB transfers 100% random 50% write, 50% read |
| 1MB Sequential read test access spec | 1MB transfers 100% sequential 100% read |
Issues
It wasn't all smooth sailing with the Synology Disk Station DS508. We had two disks crash simultaneously during a rebuild, despite the disks only being a few days old. The only guidance the user manual could offer for fixing a crashed-disk problem was to hot-swap the crashed drives for new ones.As two disks had shown as failed, we couldn't simply repair the RAID5 array. Removing the volume, and removing and replacing the 'crashed' disks allowed us to build a new RAID5 array using the same disks, even though there were initially some issues in having the disks initialise. The second rebuild took three hours.
A rebuild after removing and replacing disk two took just under three hours - the same as for the initial build.
A search of Synology's site leads to a number of threads where users have experienced similar problems; some believe the issue to be related to HDD hibernation settings when large disks are used.
Searching Synology's compatibility information there is no confirmation of support (or issues) for our ST3500320AS drives, even though there are listed issues for these drives in other Synology products. We disabled the hibernation feature and, hopefully, the issue will not rear its head again. Not being to enable power saving is clearly unacceptable, however.
